system.events

Querying in ClickHouse Cloud

The data in this system table is held locally on each node in ClickHouse Cloud. Obtaining a complete view of all data, therefore, requires the clusterAllReplicas function. See here for further details.

Contains information about the number of events that have occurred in the system. For example, in the table, you can find how many SELECT queries were processed since the ClickHouse server started.

Columns:

• event (String) — Event name.
• value (UInt64) — Number of events occurred.
• description (String) — Event description.

OSS

The following events are available in ClickHouse OSS:

Event	Description
Query	Number of queries to be interpreted and potentially executed. Does not include queries that failed to parse or were rejected due to AST size limits, quota limits or limits on the number of simultaneously running queries. May include internal queries initiated by ClickHouse itself. Does not count subqueries.
SelectQuery	Same as Query, but only for SELECT queries.
InitialQuery	Same as Query, but only counts initial queries (see is_initial_query).
InitialSelectQuery	Same as InitialQuery, but only for SELECT queries.
QueriesWithSubqueries	Count queries with all subqueries
SelectQueriesWithSubqueries	Count SELECT queries with all subqueries
FileOpen	Number of files opened.
Seek	Number of times the 'lseek' function was called.
ReadBufferFromFileDescriptorRead	Number of reads (read/pread) from a file descriptor. Does not include sockets.
ReadBufferFromFileDescriptorReadBytes	Number of bytes read from file descriptors. If the file is compressed, this will show the compressed data size.
WriteBufferFromFileDescriptorWrite	Number of writes (write/pwrite) to a file descriptor. Does not include sockets.
WriteBufferFromFileDescriptorWriteBytes	Number of bytes written to file descriptors. If the file is compressed, this will show compressed data size.
FileSync	Number of times the F_FULLFSYNC/fsync/fdatasync function was called for files.
FileSyncElapsedMicroseconds	Total time spent waiting for F_FULLFSYNC/fsync/fdatasync syscall for files.
IOBufferAllocs	Number of allocations of IO buffers (for ReadBuffer/WriteBuffer).
IOBufferAllocBytes	Number of bytes allocated for IO buffers (for ReadBuffer/WriteBuffer).
DiskReadElapsedMicroseconds	Total time spent waiting for read syscall. This include reads from page cache.
DiskWriteElapsedMicroseconds	Total time spent waiting for write syscall. This include writes to page cache.
NetworkReceiveElapsedMicroseconds	Total time spent waiting for data to receive or receiving data from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
NetworkSendElapsedMicroseconds	Total time spent waiting for data to send to network or sending data to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
NetworkReceiveBytes	Total number of bytes received from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
NetworkSendBytes	Total number of bytes send to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
GlobalThreadPoolExpansions	Counts the total number of times new threads have been added to the global thread pool. This metric indicates the frequency of expansions in the global thread pool to accommodate increased processing demands.
GlobalThreadPoolThreadCreationMicroseconds	Total time spent waiting for new threads to start.
GlobalThreadPoolLockWaitMicroseconds	Total time threads have spent waiting for locks in the global thread pool.
GlobalThreadPoolJobs	Counts the number of jobs that have been pushed to the global thread pool.
GlobalThreadPoolJobWaitTimeMicroseconds	Measures the elapsed time from when a job is scheduled in the thread pool to when it is picked up for execution by a worker thread. This metric helps identify delays in job processing, indicating the responsiveness of the thread pool to new tasks.
LocalThreadPoolExpansions	Counts the total number of times threads have been borrowed from the global thread pool to expand local thread pools.
LocalThreadPoolShrinks	Counts the total number of times threads have been returned to the global thread pool from local thread pools.
LocalThreadPoolThreadCreationMicroseconds	Total time local thread pools have spent waiting to borrow a thread from the global pool.
LocalThreadPoolJobs	Counts the number of jobs that have been pushed to the local thread pools.
LocalThreadPoolBusyMicroseconds	Total time threads have spent executing the actual work.
LocalThreadPoolJobWaitTimeMicroseconds	Measures the elapsed time from when a job is scheduled in the thread pool to when it is picked up for execution by a worker thread. This metric helps identify delays in job processing, indicating the responsiveness of the thread pool to new tasks.
QueryPlanOptimizeMicroseconds	Total time spent executing query plan optimizations.
ContextLock	Number of times the lock of Context was acquired or tried to acquire. This is global lock.
RWLockAcquiredReadLocks	Number of times a read lock was acquired (in a heavy RWLock).
QueryProfilerSignalOverruns	Number of times we drop processing of a query profiler signal due to overrun plus the number of signals that OS has not delivered due to overrun.
QueryProfilerRuns	Number of times QueryProfiler had been run.
MainConfigLoads	Number of times the main configuration was reloaded.
ServerStartupMilliseconds	Time elapsed from starting server to listening to sockets in milliseconds
AsyncLoaderWaitMicroseconds	Total time a query was waiting for async loader jobs.
LogTrace	Number of log messages with level Trace
LogDebug	Number of log messages with level Debug
LogInfo	Number of log messages with level Info
LogWarning	Number of log messages with level Warning
LoggerElapsedNanoseconds	Cumulative time spend in logging
InterfaceNativeSendBytes	Number of bytes sent through native interfaces
InterfaceNativeReceiveBytes	Number of bytes received through native interfaces
MemoryWorkerRun	Number of runs done by MemoryWorker in background
MemoryWorkerRunElapsedMicroseconds	Total time spent by MemoryWorker for background work
AsyncLoggingFileLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the file log
AsyncLoggingErrorFileLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the error file log
AsyncLoggingTextLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the text_log

Cloud

The following events are available in ClickHouse Cloud:

Event	Description
Query	Number of queries to be interpreted and potentially executed. Does not include queries that failed to parse or were rejected due to AST size limits, quota limits or limits on the number of simultaneously running queries. May include internal queries initiated by ClickHouse itself. Does not count subqueries.
SelectQuery	Same as Query, but only for SELECT queries.
InitialQuery	Same as Query, but only counts initial queries (see is_initial_query).
QueriesWithSubqueries	Count queries with all subqueries
SelectQueriesWithSubqueries	Count SELECT queries with all subqueries
SelectQueriesWithPrimaryKeyUsage	Count SELECT queries which use the primary key to evaluate the WHERE condition
QueryTimeMicroseconds	Total time of all queries.
SelectQueryTimeMicroseconds	Total time of SELECT queries.
OtherQueryTimeMicroseconds	Total time of queries that are not SELECT or INSERT.
FileOpen	Number of files opened.
Seek	Number of times the 'lseek' function was called.
ReadBufferFromFileDescriptorRead	Number of reads (read/pread) from a file descriptor. Does not include sockets.
ReadBufferFromFileDescriptorReadBytes	Number of bytes read from file descriptors. If the file is compressed, this will show the compressed data size.
WriteBufferFromFileDescriptorWrite	Number of writes (write/pwrite) to a file descriptor. Does not include sockets.
WriteBufferFromFileDescriptorWriteBytes	Number of bytes written to file descriptors. If the file is compressed, this will show compressed data size.
ReadCompressedBytes	Number of bytes (the number of bytes before decompression) read from compressed sources (files, network).
CompressedReadBufferBlocks	Number of compressed blocks (the blocks of data that are compressed independent of each other) read from compressed sources (files, network).
CompressedReadBufferBytes	Number of uncompressed bytes (the number of bytes after decompression) read from compressed sources (files, network).
OpenedFileCacheHits	Number of times a file has been found in the opened file cache, so we didn't have to open it again.
OpenedFileCacheMisses	Number of times a file has been found in the opened file cache, so we had to open it again.
OpenedFileCacheMicroseconds	Amount of time spent executing OpenedFileCache methods.
IOBufferAllocs	Number of allocations of IO buffers (for ReadBuffer/WriteBuffer).
IOBufferAllocBytes	Number of bytes allocated for IO buffers (for ReadBuffer/WriteBuffer).
ArenaAllocChunks	Number of chunks allocated for memory Arena (used for GROUP BY and similar operations)
ArenaAllocBytes	Number of bytes allocated for memory Arena (used for GROUP BY and similar operations)
FunctionExecute	Number of SQL ordinary function calls (SQL functions are called on per-block basis, so this number represents the number of blocks).
TableFunctionExecute	Number of table function calls.
DefaultImplementationForNullsRows	Number of rows processed by default implementation for nulls in function execution
DefaultImplementationForNullsRowsWithNulls	Number of rows which contain null values processed by default implementation for nulls in function execution
MarkCacheHits	Number of times an entry has been found in the mark cache, so we didn't have to load a mark file.
MarkCacheMisses	Number of times an entry has not been found in the mark cache, so we had to load a mark file in memory, which is a costly operation, adding to query latency.
QueryConditionCacheHits	Number of times an entry has been found in the query condition cache (and reading of marks can be skipped). Only updated for SELECT queries with SETTING use_query_condition_cache = 1.
QueryConditionCacheMisses	Number of times an entry has not been found in the query condition cache (and reading of mark cannot be skipped). Only updated for SELECT queries with SETTING use_query_condition_cache = 1.
CreatedReadBufferOrdinary	Number of times ordinary read buffer was created for reading data (while choosing among other read methods).
DiskReadElapsedMicroseconds	Total time spent waiting for read syscall. This include reads from page cache.
DiskWriteElapsedMicroseconds	Total time spent waiting for write syscall. This include writes to page cache.
NetworkReceiveElapsedMicroseconds	Total time spent waiting for data to receive or receiving data from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
NetworkSendElapsedMicroseconds	Total time spent waiting for data to send to network or sending data to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
NetworkReceiveBytes	Total number of bytes received from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
NetworkSendBytes	Total number of bytes send to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
GlobalThreadPoolExpansions	Counts the total number of times new threads have been added to the global thread pool. This metric indicates the frequency of expansions in the global thread pool to accommodate increased processing demands.
GlobalThreadPoolThreadCreationMicroseconds	Total time spent waiting for new threads to start.
GlobalThreadPoolLockWaitMicroseconds	Total time threads have spent waiting for locks in the global thread pool.
GlobalThreadPoolJobs	Counts the number of jobs that have been pushed to the global thread pool.
GlobalThreadPoolJobWaitTimeMicroseconds	Measures the elapsed time from when a job is scheduled in the thread pool to when it is picked up for execution by a worker thread. This metric helps identify delays in job processing, indicating the responsiveness of the thread pool to new tasks.
LocalThreadPoolExpansions	Counts the total number of times threads have been borrowed from the global thread pool to expand local thread pools.
LocalThreadPoolShrinks	Counts the total number of times threads have been returned to the global thread pool from local thread pools.
LocalThreadPoolThreadCreationMicroseconds	Total time local thread pools have spent waiting to borrow a thread from the global pool.
LocalThreadPoolLockWaitMicroseconds	Total time threads have spent waiting for locks in the local thread pools.
LocalThreadPoolJobs	Counts the number of jobs that have been pushed to the local thread pools.
LocalThreadPoolBusyMicroseconds	Total time threads have spent executing the actual work.
LocalThreadPoolJobWaitTimeMicroseconds	Measures the elapsed time from when a job is scheduled in the thread pool to when it is picked up for execution by a worker thread. This metric helps identify delays in job processing, indicating the responsiveness of the thread pool to new tasks.
RemoteReadThrottlerBytes	Bytes passed through 'max_remote_read_network_bandwidth_for_server'/'max_remote_read_network_bandwidth' throttler.
RemoteWriteThrottlerBytes	Bytes passed through 'max_remote_write_network_bandwidth_for_server'/'max_remote_write_network_bandwidth' throttler.
InsertedRows	Number of rows INSERTed to all tables.
InsertedBytes	Number of bytes (uncompressed; for columns as they stored in memory) INSERTed to all tables.
ZooKeeperInit	Number of times connection with ZooKeeper has been established.
ZooKeeperTransactions	Number of ZooKeeper operations, which include both read and write operations as well as multi-transactions.
ZooKeeperList	Number of 'list' (getChildren) requests to ZooKeeper.
ZooKeeperCreate	Number of 'create' requests to ZooKeeper.
ZooKeeperRemove	Number of 'remove' requests to ZooKeeper.
ZooKeeperExists	Number of 'exists' requests to ZooKeeper.
ZooKeeperGet	Number of 'get' requests to ZooKeeper.
ZooKeeperSet	Number of 'set' requests to ZooKeeper.
ZooKeeperMulti	Number of 'multi' requests to ZooKeeper (compound transactions).
ZooKeeperMultiRead	Number of read 'multi' requests to ZooKeeper (compound transactions).
ZooKeeperMultiWrite	Number of write 'multi' requests to ZooKeeper (compound transactions).
ZooKeeperSync	Number of 'sync' requests to ZooKeeper. These requests are rarely needed or usable.
ZooKeeperClose	Number of times connection with ZooKeeper has been closed voluntary.
ZooKeeperWatchResponse	Number of times watch notification has been received from ZooKeeper.
ZooKeeperWaitMicroseconds	Number of microseconds spent waiting for responses from ZooKeeper after creating a request, summed across all the requesting threads.
ZooKeeperBytesSent	Number of bytes send over network while communicating with ZooKeeper.
ZooKeeperBytesReceived	Number of bytes received over network while communicating with ZooKeeper.
DistributedConnectionTries	Total count of distributed connection attempts.
DistributedConnectionUsable	Total count of successful distributed connections to a usable server (with required table, but maybe stale).
SuspendSendingQueryToShard	Total count when sending query to shard was suspended when async_query_sending_for_remote is enabled.
CompileFunction	Number of times a compilation of generated LLVM code (to create fused function for complex expressions) was initiated.
CompileExpressionsMicroseconds	Total time spent for compilation of expressions to LLVM code.
CompileExpressionsBytes	Number of bytes used for expressions compilation.
QueryPlanOptimizeMicroseconds	Total time spent executing query plan optimizations.
SelectedParts	Number of data parts selected to read from a MergeTree table.
SelectedPartsTotal	Number of total data parts before selecting which ones to read from a MergeTree table.
SelectedRanges	Number of (non-adjacent) ranges in all data parts selected to read from a MergeTree table.
SelectedMarks	Number of marks (index granules) selected to read from a MergeTree table.
SelectedMarksTotal	Number of total marks (index granules) before selecting which ones to read from a MergeTree table.
SelectedRows	Number of rows SELECTed from all tables.
SelectedBytes	Number of bytes (uncompressed; for columns as they stored in memory) SELECTed from all tables.
RowsReadByMainReader	Number of rows read from MergeTree tables by the main reader (after PREWHERE step).
RowsReadByPrewhereReaders	Number of rows read from MergeTree tables (in total) by prewhere readers.
LoadedDataParts	Number of data parts loaded by MergeTree tables during initialization.
LoadedDataPartsMicroseconds	Microseconds spent by MergeTree tables for loading data parts during initialization.
FilteringMarksWithPrimaryKeyMicroseconds	Time spent filtering parts by PK.
WaitMarksLoadMicroseconds	Time spent loading marks
BackgroundLoadingMarksTasks	Number of background tasks for loading marks
MarksTasksFromCache	Number of times marks were loaded synchronously because they were already present in the cache.
LoadedMarksFiles	Number of mark files loaded.
LoadedMarksCount	Number of marks loaded (total across columns).
LoadedMarksMemoryBytes	Size of in-memory representations of loaded marks.
LoadedPrimaryIndexFiles	Number of primary index files loaded.
LoadedPrimaryIndexRows	Number of rows of primary key loaded.
LoadedPrimaryIndexBytes	Number of rows of primary key loaded.
Merge	Number of launched background merges.
MergeSourceParts	Number of source parts scheduled for merges.
MergedRows	Rows read for background merges. This is the number of rows before merge.
MergedColumns	Number of columns merged during the horizontal stage of merges.
MergedUncompressedBytes	Uncompressed bytes (for columns as they stored in memory) that was read for background merges. This is the number before merge.
MergeTotalMilliseconds	Total time spent for background merges
MergeExecuteMilliseconds	Total busy time spent for execution of background merges
MergeHorizontalStageTotalMilliseconds	Total time spent for horizontal stage of background merges
MergeHorizontalStageExecuteMilliseconds	Total busy time spent for execution of horizontal stage of background merges
MergeVerticalStageTotalMilliseconds	Total time spent for vertical stage of background merges
MergeProjectionStageTotalMilliseconds	Total time spent for projection stage of background merges
MergeProjectionStageExecuteMilliseconds	Total busy time spent for execution of projection stage of background merges
MergePrewarmStageTotalMilliseconds	Total time spent for prewarm stage of background merges
MergePrewarmStageExecuteMilliseconds	Total busy time spent for execution of prewarm stage of background merges
MergeTreeDataWriterRows	Number of rows INSERTed to MergeTree tables.
MergeTreeDataWriterUncompressedBytes	Uncompressed bytes (for columns as they stored in memory) INSERTed to MergeTree tables.
MergeTreeDataWriterCompressedBytes	Bytes written to filesystem for data INSERTed to MergeTree tables.
MergeTreeDataWriterBlocks	Number of blocks INSERTed to MergeTree tables. Each block forms a data part of level zero.
MergeTreeDataWriterBlocksAlreadySorted	Number of blocks INSERTed to MergeTree tables that appeared to be already sorted.
MergeMutateBackgroundExecutorTaskExecuteStepMicroseconds	Time spent in executeStep() for MergeMutate executor tasks.
MergeMutateBackgroundExecutorTaskResetMicroseconds	Time spent resetting task for MergeMutate executor.
CommonBackgroundExecutorTaskExecuteStepMicroseconds	Time spent in executeStep() for Common executor tasks.
CommonBackgroundExecutorTaskResetMicroseconds	Time spent resetting task for Common executor.
MergeTreeDataWriterSortingBlocksMicroseconds	Time spent sorting blocks
InsertedCompactParts	Number of parts inserted in Compact format.
MergedIntoCompactParts	Number of parts merged into Compact format.
RegexpWithMultipleNeedlesCreated	Regular expressions with multiple needles (VectorScan library) compiled.
RegexpWithMultipleNeedlesGlobalCacheHit	Number of times we fetched compiled regular expression with multiple needles (VectorScan library) from the global cache.
RegexpWithMultipleNeedlesGlobalCacheMiss	Number of times we failed to fetch compiled regular expression with multiple needles (VectorScan library) from the global cache.
ContextLock	Number of times the lock of Context was acquired or tried to acquire. This is global lock.
ContextLockWaitMicroseconds	Context lock wait time in microseconds
RWLockAcquiredReadLocks	Number of times a read lock was acquired (in a heavy RWLock).
PartsLockHoldMicroseconds	Total time spent holding data parts lock in MergeTree tables
PartsLockWaitMicroseconds	Total time spent waiting for data parts lock in MergeTree tables
RealTimeMicroseconds	Total (wall clock) time spent in processing (queries and other tasks) threads (note that this is a sum).
UserTimeMicroseconds	Total time spent in processing (queries and other tasks) threads executing CPU instructions in user mode. This includes time CPU pipeline was stalled due to main memory access, cache misses, branch mispredictions, hyper-threading, etc.
SystemTimeMicroseconds	Total time spent in processing (queries and other tasks) threads executing CPU instructions in OS kernel mode. This is time spent in syscalls, excluding waiting time during blocking syscalls.
MemoryAllocatorPurge	Total number of times memory allocator purge was requested
MemoryAllocatorPurgeTimeMicroseconds	Total time spent for memory allocator purge
SoftPageFaults	The number of soft page faults in query execution threads. Soft page fault usually means a miss in the memory allocator cache, which requires a new memory mapping from the OS and subsequent allocation of a page of physical memory.
OSCPUWaitMicroseconds	Total time a thread was ready for execution but waiting to be scheduled by OS, from the OS point of view.
OSCPUVirtualTimeMicroseconds	CPU time spent seen by OS. Does not include involuntary waits due to virtualization.
OSWriteBytes	Number of bytes written to disks or block devices. Doesn't include bytes that are in page cache dirty pages. May not include data that was written by OS asynchronously.
OSReadChars	Number of bytes read from filesystem, including page cache.
OSWriteChars	Number of bytes written to filesystem, including page cache.
QueryProfilerRuns	Number of times QueryProfiler had been run.
S3ReadMicroseconds	Time of GET and HEAD requests to S3 storage.
S3ReadRequestsCount	Number of GET and HEAD requests to S3 storage.
S3ReadRequestsErrors	Number of non-throttling errors in GET and HEAD requests to S3 storage.
S3ReadRequestAttempts	Number of attempts for GET and HEAD requests, including the initial try and any retries, but excluding retries performed internally by the S3 retry strategy
S3WriteMicroseconds	Time of POST, DELETE, PUT and PATCH requests to S3 storage.
S3WriteRequestsCount	Number of POST, DELETE, PUT and PATCH requests to S3 storage.
S3WriteRequestAttempts	Number of attempts for POST, DELETE, PUT and PATCH requests, including the initial try and any retries, but excluding retries performed internally by the retry strategy
DiskS3ReadMicroseconds	Time of GET and HEAD requests to DiskS3 storage.
DiskS3ReadRequestsCount	Number of GET and HEAD requests to DiskS3 storage.
DiskS3ReadRequestsErrors	Number of non-throttling errors in GET and HEAD requests to DiskS3 storage.
DiskS3ReadRequestAttempts	Number of attempts for GET and HEAD requests to DiskS3 storage, including the initial try and any retries, but excluding retries performed internally by the S3 retry strategy
DiskS3WriteMicroseconds	Time of POST, DELETE, PUT and PATCH requests to DiskS3 storage.
DiskS3WriteRequestsCount	Number of POST, DELETE, PUT and PATCH requests to DiskS3 storage.
DiskS3WriteRequestAttempts	Number of attempts for POST, DELETE, PUT and PATCH requests to DiskS3 storage, including the initial try and any retries, but excluding retries performed internally by the retry strategy
S3DeleteObjects	Number of S3 API DeleteObject(s) calls.
S3ListObjects	Number of S3 API ListObjects calls.
S3HeadObject	Number of S3 API HeadObject calls.
S3PutObject	Number of S3 API PutObject calls.
S3GetObject	Number of S3 API GetObject calls.
DiskS3DeleteObjects	Number of DiskS3 API DeleteObject(s) calls.
DiskS3ListObjects	Number of DiskS3 API ListObjects calls.
DiskS3HeadObject	Number of DiskS3 API HeadObject calls.
DiskS3PutObject	Number of DiskS3 API PutObject calls.
DiskS3GetObject	Number of DiskS3 API GetObject calls.
DiskPlainRewritableS3DirectoryCreated	Number of directories created by the 'plain_rewritable' metadata storage for S3ObjectStorage.
DiskPlainRewritableS3DirectoryRemoved	Number of directories removed by the 'plain_rewritable' metadata storage for S3ObjectStorage.
S3Clients	Number of created S3 clients.
ReadBufferFromS3Microseconds	Time spent on reading from S3.
ReadBufferFromS3InitMicroseconds	Time spent initializing connection to S3.
ReadBufferFromS3Bytes	Bytes read from S3.
WriteBufferFromS3Microseconds	Time spent on writing to S3.
WriteBufferFromS3Bytes	Bytes written to S3.
CachedReadBufferReadFromCacheHits	Number of times the read from filesystem cache hit the cache.
CachedReadBufferReadFromCacheMisses	Number of times the read from filesystem cache miss the cache.
CachedReadBufferReadFromSourceMicroseconds	Time reading from filesystem cache source (from remote filesystem, etc)
CachedReadBufferReadFromCacheMicroseconds	Time reading from filesystem cache
CachedReadBufferReadFromSourceBytes	Bytes read from filesystem cache source (from remote fs, etc)
CachedReadBufferReadFromCacheBytes	Bytes read from filesystem cache
CachedReadBufferCacheWriteBytes	Bytes written from source (remote fs, etc) to filesystem cache
CachedReadBufferCacheWriteMicroseconds	Time spent writing data into filesystem cache
CachedReadBufferCreateBufferMicroseconds	Prepare buffer time
CachedWriteBufferCacheWriteBytes	Bytes written from source (remote fs, etc) to filesystem cache
CachedWriteBufferCacheWriteMicroseconds	Time spent writing data into filesystem cache
FilesystemCacheLoadMetadataMicroseconds	Time spent loading filesystem cache metadata
FilesystemCacheCreatedKeyDirectories	Number of created key directories
FilesystemCacheBackgroundDownloadQueuePush	Number of file segments sent for background download in filesystem cache
FilesystemCacheLockKeyMicroseconds	Lock cache key time
FilesystemCacheLockMetadataMicroseconds	Lock filesystem cache metadata time
FilesystemCacheLockCacheMicroseconds	Lock filesystem cache time
FilesystemCacheReserveMicroseconds	Filesystem cache space reservation time
FilesystemCacheReserveAttempts	Filesystem cache space reservation attempt
FilesystemCacheGetOrSetMicroseconds	Filesystem cache getOrSet() time
FilesystemCacheGetMicroseconds	Filesystem cache get() time
FileSegmentCompleteMicroseconds	Duration of FileSegment::complete() in filesystem cache
FileSegmentLockMicroseconds	Lock file segment time
FileSegmentWriteMicroseconds	File segment write() time
FileSegmentUseMicroseconds	File segment use() time
FileSegmentHolderCompleteMicroseconds	File segments holder complete() time
FileSegmentFailToIncreasePriority	Number of times the priority was not increased due to a high contention on the cache lock
FilesystemCacheHoldFileSegments	Filesystem cache file segments count, which were hold
FilesystemCacheUnusedHoldFileSegments	Filesystem cache file segments count, which were hold, but not used (because of seek or LIMIT n, etc)
RemoteFSSeeks	Total number of seeks for async buffer
RemoteFSPrefetches	Number of prefetches made with asynchronous reading from remote filesystem
RemoteFSCancelledPrefetches	Number of cancelled prefecthes (because of seek)
RemoteFSUnusedPrefetches	Number of prefetches pending at buffer destruction
RemoteFSPrefetchedReads	Number of reads from prefecthed buffer
RemoteFSPrefetchedBytes	Number of bytes from prefecthed buffer
RemoteFSUnprefetchedReads	Number of reads from unprefetched buffer
RemoteFSUnprefetchedBytes	Number of bytes from unprefetched buffer
RemoteFSBuffers	Number of buffers created for asynchronous reading from remote filesystem
WaitPrefetchTaskMicroseconds	Time spend waiting for prefetched reader
ThreadpoolReaderTaskMicroseconds	Time spent getting the data in asynchronous reading
ThreadpoolReaderReadBytes	Bytes read from a threadpool task in asynchronous reading
ThreadpoolReaderSubmit	Bytes read from a threadpool task in asynchronous reading
ThreadpoolReaderSubmitReadSynchronously	How many times we haven't scheduled a task on the thread pool and read synchronously instead
ThreadpoolReaderSubmitReadSynchronouslyBytes	How many bytes were read synchronously
ThreadpoolReaderSubmitReadSynchronouslyMicroseconds	How much time we spent reading synchronously
ThreadpoolReaderSubmitLookupInCacheMicroseconds	How much time we spent checking if content is cached
FileSegmentWaitReadBufferMicroseconds	Metric per file segment. Time spend waiting for internal read buffer (includes cache waiting)
FileSegmentReadMicroseconds	Metric per file segment. Time spend reading from file
FileSegmentCacheWriteMicroseconds	Metric per file segment. Time spend writing data to cache
FileSegmentUsedBytes	Metric per file segment. How many bytes were actually used from current file segment
ThreadPoolReaderPageCacheMiss	Number of times the read inside ThreadPoolReader was not done from page cache and was hand off to thread pool.
ThreadPoolReaderPageCacheMissBytes	Number of bytes read inside ThreadPoolReader when read was not done from page cache and was hand off to thread pool.
ThreadPoolReaderPageCacheMissElapsedMicroseconds	Time spent reading data inside the asynchronous job in ThreadPoolReader - when read was not done from the page cache.
SynchronousReadWaitMicroseconds	Time spent in waiting for synchronous reads in asynchronous local read.
AsynchronousRemoteReadWaitMicroseconds	Time spent in waiting for asynchronous remote reads.
SynchronousRemoteReadWaitMicroseconds	Time spent in waiting for synchronous remote reads.
MainConfigLoads	Number of times the main configuration was reloaded.
MetadataFromKeeperCacheHit	Number of times an object storage metadata request was answered from cache without making request to Keeper
MetadataFromKeeperCacheMiss	Number of times an object storage metadata request had to be answered from Keeper
MetadataFromKeeperCacheUpdateMicroseconds	Total time spent in updating the cache including waiting for responses from Keeper
MetadataFromKeeperUpdateCacheOneLevel	Number of times a cache update for one level of directory tree was done
MetadataFromKeeperTransactionCommit	Number of times metadata transaction commit was attempted
MetadataFromKeeperCleanupTransactionCommit	Number of times metadata transaction commit for deleted objects cleanup was attempted
MetadataFromKeeperOperations	Number of times a request was made to Keeper
MetadataFromKeeperIndividualOperations	Number of paths read or written by single or multi requests to Keeper
MetadataFromKeeperIndividualOperationsMicroseconds	Time spend during single or multi requests to Keeper
SharedMergeTreeMetadataCacheHintLoadedFromCache	Number of times metadata cache hint was found without going to Keeper
ScalarSubqueriesCacheMiss	Number of times a read from a scalar subquery was not cached and had to be calculated completely
ServerStartupMilliseconds	Time elapsed from starting server to listening to sockets in milliseconds
MergerMutatorsGetPartsForMergeElapsedMicroseconds	Time spent to take data parts snapshot to build ranges from them.
MergerMutatorPrepareRangesForMergeElapsedMicroseconds	Time spent to prepare parts ranges which can be merged according to merge predicate.
MergerMutatorSelectPartsForMergeElapsedMicroseconds	Time spent to select parts from ranges which can be merged.
MergerMutatorRangesForMergeCount	Amount of candidate ranges for merge
MergerMutatorPartsInRangesForMergeCount	Amount of candidate parts for merge
MergerMutatorSelectRangePartsCount	Amount of parts in selected range for merge
AsyncLoaderWaitMicroseconds	Total time a query was waiting for async loader jobs.
LogTrace	Number of log messages with level Trace
LogDebug	Number of log messages with level Debug
LogInfo	Number of log messages with level Info
LogWarning	Number of log messages with level Warning
LogError	Number of log messages with level Error
LoggerElapsedNanoseconds	Cumulative time spend in logging
InterfaceHTTPSendBytes	Number of bytes sent through HTTP interfaces
InterfaceHTTPReceiveBytes	Number of bytes received through HTTP interfaces
InterfaceNativeSendBytes	Number of bytes sent through native interfaces
InterfaceNativeReceiveBytes	Number of bytes received through native interfaces
InterfacePrometheusSendBytes	Number of bytes sent through Prometheus interfaces
InterfacePrometheusReceiveBytes	Number of bytes received through Prometheus interfaces
InterfaceInterserverSendBytes	Number of bytes sent through interserver interfaces
InterfaceInterserverReceiveBytes	Number of bytes received through interserver interfaces
SharedMergeTreeVirtualPartsUpdates	Virtual parts update count
SharedMergeTreeVirtualPartsUpdatesByLeader	Virtual parts updates by leader
SharedMergeTreeVirtualPartsUpdateMicroseconds	Virtual parts update microseconds
SharedMergeTreeVirtualPartsUpdatesFromZooKeeper	Virtual parts updates count from ZooKeeper
SharedMergeTreeVirtualPartsUpdatesFromZooKeeperMicroseconds	Virtual parts updates from ZooKeeper microseconds
SharedMergeTreeVirtualPartsUpdatesPeerNotFound	Virtual updates from peer failed because no one found
SharedMergeTreeVirtualPartsUpdatesLeaderSuccessfulElection	Virtual parts updates leader election successful
SharedMergeTreeMergeMutationAssignmentAttempt	How many times we tried to assign merge or mutation
SharedMergeTreeMergeMutationAssignmentFailedWithNothingToDo	How many times we tried to assign merge or mutation and failed because nothing to merge
SharedMergeTreePartsKillerRuns	How many times parts killer has been running
SharedMergeTreePartsKillerMicroseconds	How much time does parts killer main thread takes
SharedMergeTreeMergeSelectingTaskMicroseconds	Merge selecting task microseconds for SMT
SharedMergeTreeScheduleDataProcessingJob	How many times scheduleDataProcessingJob called/
SharedMergeTreeScheduleDataProcessingJobNothingToScheduled	How many times scheduleDataProcessingJob called but nothing to do
SharedMergeTreeScheduleDataProcessingJobMicroseconds	scheduleDataProcessingJob execute time
SharedMergeTreeHandleBlockingPartsMicroseconds	Time of handling blocking parts in scheduleDataProcessingJob
SharedMergeTreeHandleFetchPartsMicroseconds	Time of handling fetched parts in scheduleDataProcessingJob
SharedMergeTreeHandleOutdatedPartsMicroseconds	Time of handling outdated parts in scheduleDataProcessingJob
SharedMergeTreeTryUpdateDiskMetadataCacheForPartMicroseconds	Time of tryUpdateDiskMetadataCacheForPart in scheduleDataProcessingJob
DiskConnectionsCreated	Number of created connections for disk
DiskConnectionsReused	Number of reused connections for disk
DiskConnectionsReset	Number of reset connections for disk
DiskConnectionsPreserved	Number of preserved connections for disk
DiskConnectionsExpired	Number of expired connections for disk
DiskConnectionsElapsedMicroseconds	Total time spend on creating connections for disk
HTTPConnectionsCreated	Number of created client HTTP connections
HTTPConnectionsReused	Number of reused client HTTP connections
HTTPConnectionsPreserved	Number of preserved client HTTP connections
HTTPConnectionsElapsedMicroseconds	Total time spend on creating client HTTP connections
HTTPServerConnectionsCreated	Number of created server HTTP connections
HTTPServerConnectionsReused	Number of reused server HTTP connections
HTTPServerConnectionsPreserved	Number of preserved server HTTP connections. Connection kept alive successfully
HTTPServerConnectionsExpired	Number of expired server HTTP connections.
HTTPServerConnectionsReset	Number of reset server HTTP connections. Server closes connection
AddressesDiscovered	Total count of new addresses in DNS resolve results for HTTP connections
ReadWriteBufferFromHTTPRequestsSent	Number of HTTP requests sent by ReadWriteBufferFromHTTP
ReadWriteBufferFromHTTPBytes	Total size of payload bytes received and sent by ReadWriteBufferFromHTTP. Doesn't include HTTP headers.
ConcurrencyControlSlotsGranted	Number of CPU slot granted according to guarantee of 1 thread per query and for queries with setting 'use_concurrency_control' = 0
ConcurrencyControlSlotsAcquiredNonCompeting	Total number of noncompeting CPU slot acquired
MemoryWorkerRun	Number of runs done by MemoryWorker in background
MemoryWorkerRunElapsedMicroseconds	Total time spent by MemoryWorker for background work
FilterTransformPassedRows	Number of rows that passed the filter in the query
FilterTransformPassedBytes	Number of bytes that passed the filter in the query
IndexBinarySearchAlgorithm	Number of times the binary search algorithm is used over the index marks
IndexGenericExclusionSearchAlgorithm	Number of times the generic exclusion search algorithm is used over the index marks
AsyncLoggingConsoleTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the console log
AsyncLoggingFileLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the file log
AsyncLoggingErrorFileLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the error file log
AsyncLoggingTextLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the text_log

Example

SELECT * FROM system.events LIMIT 5

┌─event─────────────────────────────────┬─value─┬─description────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Query                                 │    12 │ Number of queries to be interpreted and potentially executed. Does not include queries that failed to parse or were rejected due to AST size limits, quota limits or limits on the number of simultaneously running queries. May include internal queries initiated by ClickHouse itself. Does not count subqueries.                  │
│ SelectQuery                           │     8 │ Same as Query, but only for SELECT queries.                                                                                                                                                                                                                │
│ FileOpen                              │    73 │ Number of files opened.                                                                                                                                                                                                                                    │
│ ReadBufferFromFileDescriptorRead      │   155 │ Number of reads (read/pread) from a file descriptor. Does not include sockets.                                                                                                                                                                             │
│ ReadBufferFromFileDescriptorReadBytes │  9931 │ Number of bytes read from file descriptors. If the file is compressed, this will show the compressed data size.                                                                                                                                              │
└───────────────────────────────────────┴───────┴────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

Event descriptions

Event	Description
ACMEAPIRequests	Number of ACME API requests issued.
ACMECertificateOrders	Number of ACME certificate orders issued.
AIORead	Number of reads with Linux or FreeBSD AIO interface
AIOReadBytes	Number of bytes read with Linux or FreeBSD AIO interface
AIOWrite	Number of writes with Linux or FreeBSD AIO interface
AIOWriteBytes	Number of bytes written with Linux or FreeBSD AIO interface
ASTFuzzerQueries	Number of fuzzed queries attempted by the server-side AST fuzzer.
AddressesDiscovered	Total count of new addresses in DNS resolve results for HTTP connections
AddressesExpired	Total count of expired addresses which is no longer presented in DNS resolve results for HTTP connections
AddressesMarkedAsFailed	Total count of addresses which have been marked as faulty due to connection errors for HTTP connections
AggregatingSortedMilliseconds	Total time spent while aggregating sorted columns
AggregationHashTablesInitializedAsTwoLevel	How many hash tables were inited as two-level for aggregation.
AggregationOptimizedEqualRangesOfKeys	For how many blocks optimization of equal ranges of keys was applied
AggregationPreallocatedElementsInHashTables	How many elements were preallocated in hash tables for aggregation.
AnalyzePatchRangesMicroseconds	Total time spent analyzing index of patch parts
ApplyPatchesMicroseconds	Total time spent applying patch parts to blocks
ArenaAllocBytes	Number of bytes allocated for memory Arena (used for GROUP BY and similar operations)
ArenaAllocChunks	Number of chunks allocated for memory Arena (used for GROUP BY and similar operations)
AsyncInsertBytes	Data size in bytes of asynchronous INSERT queries.
AsyncInsertCacheHits	Number of times a duplicate hash id has been found in asynchronous INSERT hash id cache.
AsyncInsertQuery	Same as InsertQuery, but only for asynchronous INSERT queries.
AsyncInsertRows	Number of rows inserted by asynchronous INSERT queries.
AsyncLoaderWaitMicroseconds	Total time a query was waiting for async loader jobs.
AsyncLoggingConsoleDroppedMessages	How many messages have been dropped from the console log due to the async log queue being full
AsyncLoggingConsoleTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the console log
AsyncLoggingErrorFileLogDroppedMessages	How many messages have been dropped from error file log due to the async log queue being full
AsyncLoggingErrorFileLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the error file log
AsyncLoggingFileLogDroppedMessages	How many messages have been dropped from the file log due to the async log queue being full
AsyncLoggingFileLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the file log
AsyncLoggingSyslogDroppedMessages	How many messages have been dropped from the syslog due to the async log queue being full
AsyncLoggingSyslogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the syslog
AsyncLoggingTextLogDroppedMessages	How many messages have been dropped from text_log due to the async log queue being full
AsyncLoggingTextLogTotalMessages	How many messages (accepted or dropped) have been sent to the async queue for the text_log
AsynchronousReadWaitMicroseconds	Time spent in waiting for asynchronous reads in asynchronous local read.
AsynchronousReaderIgnoredBytes	Number of bytes ignored during asynchronous reading
AsynchronousRemoteReadWaitMicroseconds	Time spent in waiting for asynchronous remote reads.
AzureCommitBlockList	Number of Azure blob storage API CommitBlockList calls
AzureCopyObject	Number of Azure blob storage API CopyObject calls
AzureCreateContainer	Number of Azure blob storage API CreateContainer calls.
AzureDeleteObjects	Number of Azure blob storage API DeleteObject(s) calls.
AzureGetObject	Number of Azure API GetObject calls.
AzureGetProperties	Number of Azure blob storage API GetProperties calls.
AzureGetRequestThrottlerBlocked	Number of Azure GET requests blocked by throttler.
AzureGetRequestThrottlerCount	Number of Azure GET requests passed through throttler: blocked and not blocked.
AzureGetRequestThrottlerSleepMicroseconds	Total time a query was sleeping to conform Azure GET request throttling.
AzureListObjects	Number of Azure blob storage API ListObjects calls.
AzurePutRequestThrottlerBlocked	Number of Azure PUT requests blocked by throttler.
AzurePutRequestThrottlerCount	Number of Azure PUT requests passed through throttler: blocked and not blocked.
AzurePutRequestThrottlerSleepMicroseconds	Total time a query was sleeping to conform Azure PUT request throttling.
AzureReadMicroseconds	Total time spent waiting for Azure read requests.
AzureReadRequestsCount	Number of Azure read requests.
AzureReadRequestsErrors	Number of Azure read request errors.
AzureReadRequestsRedirects	Number of Azure read request redirects.
AzureReadRequestsThrottling	Number of Azure read requests throttled.
AzureStageBlock	Number of Azure blob storage API StageBlock calls
AzureUpload	Number of Azure blob storage API Upload calls
AzureWriteMicroseconds	Total time spent waiting for Azure read requests.
AzureWriteRequestsCount	Number of Azure write requests.
AzureWriteRequestsErrors	Number of Azure write request errors.
AzureWriteRequestsRedirects	Number of Azure write request redirects.
AzureWriteRequestsThrottling	Number of Azure write requests throttled.
BackgroundLoadingMarksTasks	Number of background tasks for loading marks
BackupEntriesCollectorForTablesDataMicroseconds	Time spent making backup entries for tables data
BackupEntriesCollectorMicroseconds	Time spent making backup entries
BackupEntriesCollectorRunPostTasksMicroseconds	Time spent running post tasks after making backup entries
BackupLockFileReads	How many times the '.lock' file was read while making backup
BackupPreparingFileInfosMicroseconds	Time spent preparing file infos for backup entries
BackupReadLocalBytesToCalculateChecksums	Total size of files read locally to calculate checksums for backup entries
BackupReadLocalFilesToCalculateChecksums	Number of files read locally to calculate checksums for backup entries
BackupReadMetadataMicroseconds	Time spent reading backup metadata from .backup file
BackupReadRemoteBytesToCalculateChecksums	Total size of files read from remote disks to calculate checksums for backup entries
BackupReadRemoteFilesToCalculateChecksums	Number of files read from remote disks to calculate checksums for backup entries
BackupThrottlerBytes	Bytes passed through 'max_backup_bandwidth_for_server' throttler.
BackupThrottlerSleepMicroseconds	Total time a query was sleeping to conform 'max_backup_bandwidth_for_server' throttling.
BackupWriteMetadataMicroseconds	Time spent writing backup metadata to .backup file
BackupsOpenedForRead	Number of backups opened for reading
BackupsOpenedForUnlock	Number of backups opened for unlocking
BackupsOpenedForWrite	Number of backups opened for writing
BlobCopierThreadLockBlobsErrors	Number of blobs lock errors occurred during BlobCopier execution
BlobCopierThreadLockedBlobs	Number of blobs returned from metadata storage
BlobCopierThreadRecordBlobsErrors	Number of blobs recording errors occurred during BlobCopier execution
BlobCopierThreadRecordedBlobs	Number of blobs which replication by BlobCopier was recorded in metadata storage
BlobCopierThreadReplicateBlobsErrors	Number of blobs replication errors occurred during BlobCopier execution
BlobCopierThreadReplicatedBlobs	Number of blobs replicated by BlobCopier
BlobCopierThreadRuns	Number of BlobCopier thread executes
BlobKillerThreadLockBlobsErrors	Number of blobs lock errors occurred during BlobKiller execution
BlobKillerThreadLockedBlobs	Number of blobs returned from metadata storage
BlobKillerThreadRecordBlobsErrors	Number of blobs recording errors occurred during BlobKiller execution
BlobKillerThreadRecordedBlobs	Number of blobs which removal by BlobKiller was recorded in metadata storage
BlobKillerThreadRemoveBlobsErrors	Number of blobs removal errors occurred during BlobKiller execution
BlobKillerThreadRemoveTasks	Number of remove tasks created by BlobKiller
BlobKillerThreadRemovedBlobs	Number of blobs removed by BlobKiller
BlobKillerThreadRuns	Number of BlobKiller thread executes
BuildPatchesJoinMicroseconds	Total time spent building indexes and hash tables for applying patch parts with Join mode
BuildPatchesMergeMicroseconds	Total time spent building indexes for applying patch parts with Merge mode
CacheWarmerBytesDownloaded	Amount of data fetched into filesystem cache by dedicated background threads.
CacheWarmerDataPartsDownloaded	Number of data parts that were fully fetched by CacheWarmer.
CachedReadBufferCacheWriteBytes	Bytes written from source (remote fs, etc) to filesystem cache
CachedReadBufferCacheWriteMicroseconds	Time spent writing data into filesystem cache
CachedReadBufferCreateBufferMicroseconds	Prepare buffer time
CachedReadBufferPredownloadedBytes	Bytes read from filesystem cache source. Cache segments are read from left to right as a whole, it might be that we need to predownload some part of the segment irrelevant for the current task just to get to the needed data
CachedReadBufferPredownloadedFromSourceBytes	Bytes read from filesystem cache source for predownload (from remote fs, etc)
CachedReadBufferPredownloadedFromSourceMicroseconds	Time reading from filesystem cache source for predownload (from remote filesystem, etc)
CachedReadBufferReadFromCacheBytes	Bytes read from filesystem cache
CachedReadBufferReadFromCacheHits	Number of times the read from filesystem cache hit the cache.
CachedReadBufferReadFromCacheMicroseconds	Time reading from filesystem cache
CachedReadBufferReadFromCacheMisses	Number of times the read from filesystem cache miss the cache.
CachedReadBufferReadFromSourceBytes	Bytes read from filesystem cache source (from remote fs, etc)
CachedReadBufferReadFromSourceMicroseconds	Time reading from filesystem cache source (from remote filesystem, etc)
CachedReadBufferWaitReadBufferMicroseconds	Time spend waiting for internal read buffer (includes cache waiting)
CachedWriteBufferCacheWriteBytes	Bytes written from source (remote fs, etc) to filesystem cache
CachedWriteBufferCacheWriteMicroseconds	Time spent writing data into filesystem cache
CannotRemoveEphemeralNode	Number of times an error happened while trying to remove ephemeral node. This is not an issue, because our implementation of ZooKeeper library guarantee that the session will expire and the node will be removed.
CannotWriteToWriteBufferDiscard	Number of stack traces dropped by query profiler or signal handler because pipe is full or cannot write to pipe.
CoalescingSortedMilliseconds	Total time spent while coalescing sorted columns
CollapsingSortedMilliseconds	Total time spent while collapsing sorted columns
CommonBackgroundExecutorTaskCancelMicroseconds	Time spent in cancel() for Common executor tasks.
CommonBackgroundExecutorTaskExecuteStepMicroseconds	Time spent in executeStep() for Common executor tasks.
CommonBackgroundExecutorTaskResetMicroseconds	Time spent resetting task for Common executor.
CommonBackgroundExecutorWaitMicroseconds	Time spent waiting for completion in Common executor.
CompileExpressionsBytes	Number of bytes used for expressions compilation.
CompileExpressionsMicroseconds	Total time spent for compilation of expressions to LLVM code.
CompileFunction	Number of times a compilation of generated LLVM code (to create fused function for complex expressions) was initiated.
CompiledFunctionExecute	Number of times a compiled function was executed.
CompressedReadBufferBlocks	Number of compressed blocks (the blocks of data that are compressed independent of each other) read from compressed sources (files, network).
CompressedReadBufferBytes	Number of uncompressed bytes (the number of bytes after decompression) read from compressed sources (files, network).
CompressedReadBufferChecksumDoesntMatch	Number of times the compressed block checksum did not match.
CompressedReadBufferChecksumDoesntMatchMicroseconds	Total time spent detecting bit-flips due to compressed block checksum mismatches.
CompressedReadBufferChecksumDoesntMatchSingleBitMismatch	Number of times a compressed block checksum mismatch was caused by a single-bit difference.
ConcurrencyControlDownscales	Total number of CPU downscaling events
ConcurrencyControlPreemptedMicroseconds	Total time a query was waiting due to preemption of CPU slots.
ConcurrencyControlPreemptions	Total number of CPU preemptions
ConcurrencyControlQueriesDelayed	Total number of CPU slot allocations (queries) that were required to wait for slots to upscale
ConcurrencyControlSlotsAcquired	Total number of CPU slots acquired
ConcurrencyControlSlotsAcquiredNonCompeting	Total number of noncompeting CPU slot acquired
ConcurrencyControlSlotsDelayed	Number of CPU slot not granted initially and required to wait for a free CPU slot
ConcurrencyControlSlotsGranted	Number of CPU slot granted according to guarantee of 1 thread per query and for queries with setting 'use_concurrency_control' = 0
ConcurrencyControlUpscales	Total number of CPU upscaling events
ConcurrencyControlWaitMicroseconds	Total time a query was waiting on resource requests for CPU slots.
ConcurrentQuerySlotsAcquired	Total number of query slots acquired
ConcurrentQueryWaitMicroseconds	Total time a query was waiting for a query slots
ConnectionPoolIsFullMicroseconds	Total time spent waiting for a slot in connection pool.
ContextLock	Number of times the lock of Context was acquired or tried to acquire. This is global lock.
ContextLockWaitMicroseconds	Context lock wait time in microseconds
CoordinatedMergesMergeAssignmentRequest	Total number of merge assignment requests
CoordinatedMergesMergeAssignmentRequestMicroseconds	Total time spend in merge assignment client
CoordinatedMergesMergeAssignmentResponse	Total number of merge assignment requests
CoordinatedMergesMergeAssignmentResponseMicroseconds	Total time spend in merge assignment handler
CoordinatedMergesMergeCoordinatorFetchMetadataMicroseconds	Total time spend on fetching fresh metadata inside merge coordinator
CoordinatedMergesMergeCoordinatorFilterMicroseconds	Total time spend on filtering prepared merges inside merge coordinator
CoordinatedMergesMergeCoordinatorLockStateExclusivelyCount	Total number of exclusive captures of coordinator state lock
CoordinatedMergesMergeCoordinatorLockStateExclusivelyMicroseconds	Total time spend on locking coordinator state mutex exclusively
CoordinatedMergesMergeCoordinatorLockStateForShareCount	Total number of for share captures of coordinator state lock
CoordinatedMergesMergeCoordinatorLockStateForShareMicroseconds	Total time spend on locking coordinator state mutex for share
CoordinatedMergesMergeCoordinatorSelectMergesMicroseconds	Total time spend on finding merge using merge selectors inside merge coordinator
CoordinatedMergesMergeCoordinatorUpdateCount	Total number of merge coordinator updates
CoordinatedMergesMergeCoordinatorUpdateMicroseconds	Total time spend on updating merge coordinator state
CoordinatedMergesMergeWorkerUpdateCount	Total number merge worker updates
CoordinatedMergesMergeWorkerUpdateMicroseconds	Total time spend on updating local state of assigned merges on worker
CreatedLogEntryForMerge	Successfully created log entry to merge parts in ReplicatedMergeTree.
CreatedLogEntryForMutation	Successfully created log entry to mutate parts in ReplicatedMergeTree.
CreatedReadBufferDirectIO	Number of times a read buffer with O_DIRECT was created for reading data (while choosing among other read methods).
CreatedReadBufferDirectIOFailed	Number of times a read buffer with O_DIRECT was attempted to be created for reading data (while choosing among other read methods), but the OS did not allow it (due to lack of filesystem support or other reasons) and we fallen back to the ordinary reading method.
CreatedReadBufferMMap	Number of times a read buffer using 'mmap' was created for reading data (while choosing among other read methods).
CreatedReadBufferMMapFailed	Number of times a read buffer with 'mmap' was attempted to be created for reading data (while choosing among other read methods), but the OS did not allow it (due to lack of filesystem support or other reasons) and we fallen back to the ordinary reading method.
CreatedReadBufferOrdinary	Number of times ordinary read buffer was created for reading data (while choosing among other read methods).
DNSError	Total count of errors in DNS resolution
DataAfterMergeDiffersFromReplica
Number of times data after merge is not byte-identical to the data on another replicas. There could be several reasons:

1. Using newer version of compression library after server update.
2. Using another compression method.
3. Non-deterministic compression algorithm (highly unlikely).
4. Non-deterministic merge algorithm due to logical error in code.
5. Data corruption in memory due to bug in code.
6. Data corruption in memory due to hardware issue.
7. Manual modification of source data after server startup.
8. Manual modification of checksums stored in ZooKeeper.
9. Part format related settings like 'enable_mixed_granularity_parts' are different on different replicas. The server successfully detected this situation and will download merged part from the replica to force the byte-identical result. | | DataAfterMutationDiffersFromReplica | Number of times data after mutation is not byte-identical to the data on other replicas. In addition to the reasons described in 'DataAfterMergeDiffersFromReplica', it is also possible due to non-deterministic mutation. | | DefaultImplementationForNullsRows | Number of rows processed by default implementation for nulls in function execution | | DefaultImplementationForNullsRowsWithNulls | Number of rows which contain null values processed by default implementation for nulls in function execution | | DelayedInserts | Number of times the INSERT of a block to a MergeTree table was throttled due to high number of active data parts for partition. | | DelayedInsertsMilliseconds | Total number of milliseconds spent while the INSERT of a block to a MergeTree table was throttled due to high number of active data parts for partition. | | DelayedMutations | Number of times the mutation of a MergeTree table was throttled due to high number of unfinished mutations for table. | | DelayedMutationsMilliseconds | Total number of milliseconds spent while the mutation of a MergeTree table was throttled due to high number of unfinished mutations for table. | | DeltaLakePartitionPrunedFiles | Number of skipped files during DeltaLake partition pruning | | DeltaLakeScannedFiles | Number of files scanned during DeltaLake scan callbacks | | DeltaLakeSnapshotInitializations | Number of times a DeltaLake table snapshot was initialized (loaded from object storage) | | DictCacheKeysExpired | Number of keys looked up in the dictionaries of 'cache' types and found in the cache but they were obsolete. | | DictCacheKeysHit | Number of keys looked up in the dictionaries of 'cache' types and found in the cache. | | DictCacheKeysNotFound | Number of keys looked up in the dictionaries of 'cache' types and not found. | | DictCacheKeysRequested | Number of keys requested from the data source for the dictionaries of 'cache' types. | | DictCacheKeysRequestedFound | Number of keys requested from the data source for dictionaries of 'cache' types and found in the data source. | | DictCacheKeysRequestedMiss | Number of keys requested from the data source for dictionaries of 'cache' types but not found in the data source. | | DictCacheLockReadNs | Number of nanoseconds spend in waiting for read lock to lookup the data for the dictionaries of 'cache' types. | | DictCacheLockWriteNs | Number of nanoseconds spend in waiting for write lock to update the data for the dictionaries of 'cache' types. | | DictCacheRequestTimeNs | Number of nanoseconds spend in querying the external data sources for the dictionaries of 'cache' types. | | DictCacheRequests | Number of bulk requests to the external data sources for the dictionaries of 'cache' types. | | DirectorySync | Number of times the F_FULLFSYNC/fsync/fdatasync function was called for directories. | | DirectorySyncElapsedMicroseconds | Total time spent waiting for F_FULLFSYNC/fsync/fdatasync syscall for directories. | | DiskAzureCommitBlockList | Number of Disk Azure blob storage API CommitBlockList calls | | DiskAzureCopyObject | Number of Disk Azure blob storage API CopyObject calls | | DiskAzureCreateContainer | Number of Disk Azure blob storage API CreateContainer calls. | | DiskAzureDeleteObjects | Number of Azure blob storage API DeleteObject(s) calls. | | DiskAzureGetObject | Number of Disk Azure API GetObject calls. | | DiskAzureGetProperties | Number of Disk Azure blob storage API GetProperties calls. | | DiskAzureGetRequestThrottlerBlocked | Number of Azure disk GET requests blocked by throttler. | | DiskAzureGetRequestThrottlerCount | Number of Azure disk GET requests passed through throttler: blocked and not blocked. | | DiskAzureGetRequestThrottlerSleepMicroseconds | Total time a query was sleeping to conform Azure disk GET request throttling. | | DiskAzureListObjects | Number of Disk Azure blob storage API ListObjects calls. | | DiskAzurePutRequestThrottlerBlocked | Number of Azure disk PUT requests blocked by throttler. | | DiskAzurePutRequestThrottlerCount | Number of Azure disk PUT requests passed through throttler: blocked and not blocked. | | DiskAzurePutRequestThrottlerSleepMicroseconds | Total time a query was sleeping to conform Azure disk PUT request throttling. | | DiskAzureReadMicroseconds | Total time spent waiting for Azure disk read requests. | | DiskAzureReadRequestsCount | Number of Azure disk read requests. | | DiskAzureReadRequestsErrors | Number of Azure disk read request errors. | | DiskAzureReadRequestsRedirects | Number of Azure disk read request redirects. | | DiskAzureReadRequestsThrottling | Number of Azure disk read requests throttled. | | DiskAzureStageBlock | Number of Disk Azure blob storage API StageBlock calls | | DiskAzureUpload | Number of Disk Azure blob storage API Upload calls | | DiskAzureWriteMicroseconds | Total time spent waiting for Azure disk write requests. | | DiskAzureWriteRequestsCount | Number of Azure disk write requests. | | DiskAzureWriteRequestsErrors | Number of Azure disk write request errors. | | DiskAzureWriteRequestsRedirects | Number of Azure disk write request redirects. | | DiskAzureWriteRequestsThrottling | Number of Azure disk write requests throttled. | | DiskConnectionsCreated | Number of created connections for disk | | DiskConnectionsElapsedMicroseconds | Total time spend on creating connections for disk | | DiskConnectionsErrors | Number of cases when creation of a connection for disk is failed | | DiskConnectionsExpired | Number of expired connections for disk | | DiskConnectionsPreserved | Number of preserved connections for disk | | DiskConnectionsReset | Number of reset connections for disk | | DiskConnectionsReused | Number of reused connections for disk | | DiskPlainRewritableAzureDirectoryCreated | Number of directories created by the 'plain_rewritable' metadata storage for AzureObjectStorage. | | DiskPlainRewritableAzureDirectoryRemoved | Number of directories removed by the 'plain_rewritable' metadata storage for AzureObjectStorage. | | DiskPlainRewritableLegacyLayoutDiskCount | Number of the 'plain_rewritable' disks with legacy layout. | | DiskPlainRewritableLocalDirectoryCreated | Number of directories created by the 'plain_rewritable' metadata storage for LocalObjectStorage. | | DiskPlainRewritableLocalDirectoryRemoved | Number of directories removed by the 'plain_rewritable' metadata storage for LocalObjectStorage. | | DiskPlainRewritableS3DirectoryCreated | Number of directories created by the 'plain_rewritable' metadata storage for S3ObjectStorage. | | DiskPlainRewritableS3DirectoryRemoved | Number of directories removed by the 'plain_rewritable' metadata storage for S3ObjectStorage. | | DiskReadElapsedMicroseconds | Total time spent waiting for read syscall. This include reads from page cache. | | DiskS3AbortMultipartUpload | Number of DiskS3 API AbortMultipartUpload calls. | | DiskS3CompleteMultipartUpload | Number of DiskS3 API CompleteMultipartUpload calls. | | DiskS3CopyObject | Number of DiskS3 API CopyObject calls. | | DiskS3CreateMultipartUpload | Number of DiskS3 API CreateMultipartUpload calls. | | DiskS3DeleteObjects | Number of DiskS3 API DeleteObject(s) calls. | | DiskS3GetObject | Number of DiskS3 API GetObject calls. | | DiskS3GetObjectTagging | Number of DiskS3 API GetObjectTagging calls. | | DiskS3GetRequestThrottlerBlocked | Number of DiskS3 GET and SELECT requests blocked by throttler. | | DiskS3GetRequestThrottlerCount | Number of DiskS3 GET and SELECT requests passed through throttler: blocked and not blocked. | | DiskS3GetRequestThrottlerSleepMicroseconds | Total time a query was sleeping to conform DiskS3 GET and SELECT request throttling. | | DiskS3HeadObject | Number of DiskS3 API HeadObject calls. | | DiskS3ListObjects | Number of DiskS3 API ListObjects calls. | | DiskS3PutObject | Number of DiskS3 API PutObject calls. | | DiskS3PutRequestThrottlerBlocked | Number of DiskS3 PUT, COPY, POST and LIST requests blocked by throttler. | | DiskS3PutRequestThrottlerCount | Number of DiskS3 PUT, COPY, POST and LIST requests passed through throttler: blocked and not blocked. | | DiskS3PutRequestThrottlerSleepMicroseconds | Total time a query was sleeping to conform DiskS3 PUT, COPY, POST and LIST request throttling. | | DiskS3ReadMicroseconds | Time of GET and HEAD requests to DiskS3 storage. | | DiskS3ReadRequestAttempts | Number of attempts for GET and HEAD requests to DiskS3 storage, including the initial try and any retries, but excluding retries performed internally by the S3 retry strategy | | DiskS3ReadRequestRetryableErrors | Number of retryable errors for GET and HEAD requests to DiskS3 storage, excluding retries performed internally by the S3 retry strategy | | DiskS3ReadRequestsCount | Number of GET and HEAD requests to DiskS3 storage. | | DiskS3ReadRequestsErrors | Number of non-throttling errors in GET and HEAD requests to DiskS3 storage. | | DiskS3ReadRequestsRedirects | Number of redirects in GET and HEAD requests to DiskS3 storage. | | DiskS3ReadRequestsThrottling | Number of 429 and 503 errors in GET and HEAD requests to DiskS3 storage. | | DiskS3UploadPart | Number of DiskS3 API UploadPart calls. | | DiskS3UploadPartCopy | Number of DiskS3 API UploadPartCopy calls. | | DiskS3WriteMicroseconds | Time of POST, DELETE, PUT and PATCH requests to DiskS3 storage. | | DiskS3WriteRequestAttempts | Number of attempts for POST, DELETE, PUT and PATCH requests to DiskS3 storage, including the initial try and any retries, but excluding retries performed internally by the retry strategy | | DiskS3WriteRequestRetryableErrors | Number of retryable errors for POST, DELETE, PUT and PATCH requests to DiskS3 storage, excluding retries performed internally by the retry strategy | | DiskS3WriteRequestsCount | Number of POST, DELETE, PUT and PATCH requests to DiskS3 storage. | | DiskS3WriteRequestsErrors | Number of non-throttling errors in POST, DELETE, PUT and PATCH requests to DiskS3 storage. | | DiskS3WriteRequestsRedirects | Number of redirects in POST, DELETE, PUT and PATCH requests to DiskS3 storage. | | DiskS3WriteRequestsThrottling | Number of 429 and 503 errors in POST, DELETE, PUT and PATCH requests to DiskS3 storage. | | DiskWriteElapsedMicroseconds | Total time spent waiting for write syscall. This include writes to page cache. | | DistrCacheConnectAttempts | Distributed Cache connection event. The number of connection attempts to distributed cache | | DistrCacheConnectMicroseconds | Distributed Cache connection event. The time spent to connect to distributed cache | | DistrCacheFallbackReadMicroseconds | Distributed Cache read buffer event. Time spend reading from fallback buffer instead of distributed cache | | DistrCacheGetClientMicroseconds | Distributed Cache connection event. Time spent getting client for distributed cache | | DistrCacheGetResponseMicroseconds | Distributed Cache client event. Time spend to wait for response from distributed cache | | DistrCacheHashRingRebuilds | Distributed Cache registry event. Number of distributed cache hash ring rebuilds | | DistrCacheLockRegistryMicroseconds | Distributed Cache registry event. Time spent to take DistributedCacheRegistry lock | | DistrCacheMakeRequestErrors | Distributed Cache client event. Number of distributed cache errors when making a request | | DistrCacheNextImplMicroseconds | Distributed Cache read buffer event. Time spend in ReadBufferFromDistributedCache::nextImpl | | DistrCacheOpenedConnections | Distributed Cache connection event. The number of open connections to distributed cache | | DistrCacheOpenedConnectionsBypassingPool | Distributed Cache connection event. The number of open connections to distributed cache bypassing pool | | DistrCachePrecomputeRangesMicroseconds | Distributed Cache read buffer event. Time spent to precompute read ranges | | DistrCacheRangeChange | Distributed Cache read buffer event. Number of times we changed read range because of seek/last_position change | | DistrCacheRangeResetBackward | Distributed Cache read buffer event. Number of times we reset read range because of seek/last_position change | | DistrCacheRangeResetForward | Distributed Cache read buffer event. Number of times we reset read range because of seek/last_position change | | DistrCacheReadBytesFromFallbackBuffer | Distributed Cache read buffer event. Bytes read from fallback buffer | | DistrCacheReadErrors | Distributed Cache read buffer event. Number of distributed cache errors during read | | DistrCacheReadMicroseconds | Distributed Cache read buffer event. Time spent reading from distributed cache | | DistrCacheReadThrottlerBytes | Bytes passed through 'max_distributed_cache_read_bandwidth_for_server' throttler. | | DistrCacheReadThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_distributed_cache_read_bandwidth_for_server' throttling. | | DistrCacheReceiveResponseErrors | Distributed Cache client event. Number of distributed cache errors when receiving response a request | | DistrCacheReceivedCredentialsRefreshPackets | Distributed Cache client event. Total number of received RefreshCredentials packets received from distributed cache | | DistrCacheReceivedDataPackets | Distributed Cache client event. Total number of received data packets received from distributed cache | | DistrCacheReceivedDataPacketsBytes | Distributed Cache client event. The number of bytes in Data packets received from distributed cache | | DistrCacheReceivedErrorPackets | Distributed Cache client event. Total number of received Error packets received from distributed cache | | DistrCacheReceivedOkPackets | Distributed Cache client event. Total number of received Ok packets received from distributed cache | | DistrCacheReceivedStopPackets | Distributed Cache client event. Total number of received Stop packets received from distributed cache | | DistrCacheReconnectsAfterTimeout | Distributed Cache read buffer event. The number of reconnects after timeout | | DistrCacheRegistryUpdateMicroseconds | Distributed Cache registry event. Time spent updating distributed cache registry | | DistrCacheRegistryUpdates | Distributed Cache registry event. Number of distributed cache registry updates | | DistrCacheReusedConnections | Distributed Cache connection event. The number of reused connections to distributed cache | | DistrCacheSentDataPackets | Distributed Cache client event. Total number of data packets sent to distributed cache | | DistrCacheSentDataPacketsBytes | Distributed Cache client event. The number of bytes in Data packets sent to distributed cache | | DistrCacheServerAckRequestPackets | Distributed Cache server event. Number of AckRequest packets in DistributedCacheServer | | DistrCacheServerCachedReadBufferCacheHits | Distributed Cache server event. The number of times distributed cache hit the cache while reading from filesystem cache | | DistrCacheServerCachedReadBufferCacheMisses | Distributed Cache server event. The number of times distributed cache missed the cache while reading from filesystem cache | | DistrCacheServerCachedReadBufferCachePredownloadBytes | Distributed Cache server event. The number of bytes read from object storage for predownload in distributed cache while reading from filesystem cache | | DistrCacheServerCachedReadBufferCacheReadBytes | Distributed Cache server event. The number of bytes read from cache in distributed cache while reading from filesystem cache | | DistrCacheServerCachedReadBufferCacheWrittenBytes | Distributed Cache server event. The number of bytes written to cache in distributed cache while reading from filesystem cache | | DistrCacheServerCachedReadBufferObjectStorageReadBytes | Distributed Cache server event. The number of bytes read from object storage in distributed cache while reading from filesystem cache | | DistrCacheServerContinueRequestPackets | Distributed Cache server event. Number of ContinueRequest packets in DistributedCacheServer | | DistrCacheServerCredentialsRefresh | Distributed Cache server event. The number of expired credentials were refreshed | | DistrCacheServerEndRequestPackets | Distributed Cache server event. Number of EndRequest packets in DistributedCacheServer | | DistrCacheServerNewS3CachedClients | Distributed Cache server event. The number of new cached s3 clients | | DistrCacheServerProcessRequestMicroseconds | Distributed Cache server event. Time spent processing request on DistributedCache server side | | DistrCacheServerReceivedCredentialsRefreshPackets | Distributed Cache server event. Number of RefreshCredentials client packets in DistributedCacheServer | | DistrCacheServerReusedS3CachedClients | Distributed Cache server event. The number of reused cached s3 clients | | DistrCacheServerSkipped | Distributed Cache server event. The number of times distributed cache server was skipped because of previous failed connection attempts | | DistrCacheServerStartRequestPackets | Distributed Cache server event. Number of StartRequest packets in DistributedCacheServer | | DistrCacheServerSwitches | Distributed Cache read buffer event. Number of server switches between distributed cache servers in read/write-through cache | | DistrCacheServerUpdates | Distributed Cache read buffer event. The number of server updates because server is not longer registered in keeper | | DistrCacheStartRangeMicroseconds | Distributed Cache read buffer event. Time spent to start a new read range with distributed cache | | DistrCacheSuccessfulConnectAttempts | Distributed Cache connection event. The number of successful connection attempts to distributed cache | | DistrCacheSuccessfulRegistryUpdates | Distributed Cache registry event. The number of successful server registry updates | | DistrCacheTemporaryFilesBytesWritten | Distributed Cache connection event. Number of bytes written to temporary files created in distributed cache | | DistrCacheTemporaryFilesCreated | Distributed Cache connection event. Number of temporary files created in distributed cache | | DistrCacheUnsuccessfulConnectAttempts | Distributed Cache connection event. The number of unsuccessful connection attempts to distributed cache | | DistrCacheUnsuccessfulRegistryUpdates | Distributed Cache registry event. The number of unsuccessful server registry updates | | DistrCacheUnusedDataPacketsBytes | Distributed Cache client event. The number of bytes in Data packets which were ignored | | DistrCacheUnusedPackets | Distributed Cache client event. Number of skipped unused packets from distributed cache | | DistrCacheUnusedPacketsBufferAllocations | Distributed Cache client event. The number of extra buffer allocations in case we could not reuse existing buffer | | DistrCacheWriteErrors | Distributed Cache write buffer event. Number of distributed cache errors during write | | DistrCacheWriteThrottlerBytes | Bytes passed through 'max_distributed_cache_write_bandwidth_for_server' throttler. | | DistrCacheWriteThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_distributed_cache_write_bandwidth_for_server' throttling. | | DistributedAsyncInsertionFailures | Number of failures for asynchronous insertion into a Distributed table (with 'distributed_foreground_insert' = 0) | | DistributedConnectionConnectCount | Number of connects to other servers done during distributed query execution. Happens when new connection is established instead of using existing from pool. | | DistributedConnectionFailAtAll | Total count when distributed connection fails after all retries finished. | | DistributedConnectionFailTry | Total count when distributed connection fails with retry. | | DistributedConnectionMissingTable | Number of times we rejected a replica from a distributed query, because it did not contain a table needed for the query. | | DistributedConnectionReconnectCount | Number of reconnects to other servers done during distributed query execution. It can happen when a stale connection has been acquired from connection pool | | DistributedConnectionSkipReadOnlyReplica | Number of replicas skipped during INSERT into Distributed table due to replicas being read-only | | DistributedConnectionStaleReplica | Number of times we rejected a replica from a distributed query, because some table needed for a query had replication lag higher than the configured threshold. | | DistributedConnectionTries | Total count of distributed connection attempts. | | DistributedConnectionUsable | Total count of successful distributed connections to a usable server (with required table, but maybe stale). | | DistributedDelayedInserts | Number of times the INSERT of a block to a Distributed table was throttled due to high number of pending bytes. | | DistributedDelayedInsertsMilliseconds | Total number of milliseconds spent while the INSERT of a block to a Distributed table was throttled due to high number of pending bytes. | | DistributedIndexAnalysisMicroseconds | Total time spent during distributed index analysis | | DistributedIndexAnalysisMissingParts | Number of missing parts during distributed index analysis that will be resolved locally | | DistributedIndexAnalysisParts | Number of parts send for distributed index analysis | | DistributedIndexAnalysisReplicaFallback | Number of times distributed index analysis failed on one of replicas with fallback to local replica | | DistributedIndexAnalysisReplicaUnavailable | Number of times distributed index analysis failed on one of replicas without fallback (failed during connect) | | DistributedIndexAnalysisScheduledReplicas | Number of replicas (local replica will be accounted once) to which distributed index analysis has been scheduled | | DistributedRejectedInserts | Number of times the INSERT of a block to a Distributed table was rejected with 'Too many bytes' exception due to high number of pending bytes. | | DistributedSyncInsertionTimeoutExceeded | A timeout has exceeded while waiting for shards during synchronous insertion into a Distributed table (with 'distributed_foreground_insert' = 1) | | DuplicatedAsyncInserts | Number of async inserts in the INSERTed block to a ReplicatedMergeTree table was deduplicated. | | DuplicatedInsertedBlocks | Number of the synchronous inserts to a MergeTree table was deduplicated. | | DuplicationElapsedMicroseconds | Total time spent checking for duplication of INSERTed blocks to MergeTree tables. | | EngineFileLikeReadFiles | Number of files read in table engines working with files (like File/S3/URL/HDFS). | | ExecuteShellCommand | Number of shell command executions. | | ExternalAggregationCompressedBytes | Number of bytes written to disk for aggregation in external memory. | | ExternalAggregationMerge | Number of times temporary files were merged for aggregation in external memory. | | ExternalAggregationUncompressedBytes | Amount of data (uncompressed, before compression) written to disk for aggregation in external memory. | | ExternalAggregationWritePart | Number of times a temporary file was written to disk for aggregation in external memory. | | ExternalDataSourceLocalCacheReadBytes | Bytes read from local cache buffer in RemoteReadBufferCache | | ExternalJoinCompressedBytes | Number of compressed bytes written for JOIN in external memory. | | ExternalJoinMerge | Number of times temporary files were merged for JOIN in external memory. | | ExternalJoinUncompressedBytes | Amount of data (uncompressed, before compression) written for JOIN in external memory. | | ExternalJoinWritePart | Number of times a temporary file was written to disk for JOIN in external memory. | | ExternalProcessingCompressedBytesTotal | Number of compressed bytes written by external processing (sorting/aggragating/joining) | | ExternalProcessingFilesTotal | Number of files used by external processing (sorting/aggragating/joining) | | ExternalProcessingUncompressedBytesTotal | Amount of data (uncompressed, before compression) written by external processing (sorting/aggragating/joining) | | ExternalSortCompressedBytes | Number of compressed bytes written for sorting in external memory. | | ExternalSortMerge | Number of times temporary files were merged for sorting in external memory. | | ExternalSortUncompressedBytes | Amount of data (uncompressed, before compression) written for sorting in external memory. | | ExternalSortWritePart | Number of times a temporary file was written to disk for sorting in external memory. | | FailedAsyncInsertQuery | Number of failed ASYNC INSERT queries. | | FailedInitialQuery | Number of failed initial queries. | | FailedInitialSelectQuery | Same as FailedInitialQuery, but only for SELECT queries. | | FailedInsertQuery | Same as FailedQuery, but only for INSERT queries. | | FailedInternalInsertQuery | Same as FailedInternalQuery, but only for INSERT queries. | | FailedInternalQuery | Number of failed internal queries. | | FailedInternalSelectQuery | Same as FailedInternalQuery, but only for SELECT queries. | | FailedQuery | Number of total failed queries, both internal and user queries. | | FailedSelectQuery | Same as FailedQuery, but only for SELECT queries. | | FetchBackgroundExecutorTaskCancelMicroseconds | Time spent in cancel() for Fetch executor tasks. | | FetchBackgroundExecutorTaskExecuteStepMicroseconds | Time spent in executeStep() for Fetch executor tasks. | | FetchBackgroundExecutorTaskResetMicroseconds | Time spent resetting task for Fetch executor. | | FetchBackgroundExecutorWaitMicroseconds | Time spent waiting for completion in Fetch executor. | | FileOpen | Number of files opened. | | FileSegmentCompleteMicroseconds | Duration of FileSegment::complete() in filesystem cache | | FileSegmentFailToIncreasePriority | Number of times the priority was not increased due to a high contention on the cache lock | | FileSegmentHolderCompleteMicroseconds | File segments holder complete() time | | FileSegmentIncreasePriorityMicroseconds | File segment increase priority time | | FileSegmentLockMicroseconds | Lock file segment time | | FileSegmentRemoveMicroseconds | File segment remove() time | | FileSegmentWaitMicroseconds | Wait on DOWNLOADING state | | FileSegmentWriteMicroseconds | File segment write() time | | FileSync | Number of times the F_FULLFSYNC/fsync/fdatasync function was called for files. | | FileSyncElapsedMicroseconds | Total time spent waiting for F_FULLFSYNC/fsync/fdatasync syscall for files. | | FilesystemCacheBackgroundDownloadQueuePush | Number of file segments sent for background download in filesystem cache | | FilesystemCacheBackgroundEvictedBytes | Number of bytes evicted by background thread | | FilesystemCacheBackgroundEvictedFileSegments | Number of file segments evicted by background thread | | FilesystemCacheCheckCorrectness | Number of times FileCache::assertCacheCorrectness was called | | FilesystemCacheCheckCorrectnessMicroseconds | How much time does FileCache::assertCacheCorrectness takes | | FilesystemCacheCreatedKeyDirectories | Number of created key directories | | FilesystemCacheEvictMicroseconds | Filesystem cache eviction time | | FilesystemCacheEvictedBytes | Number of bytes evicted from filesystem cache | | FilesystemCacheEvictedFileSegments | Number of file segments evicted from filesystem cache | | FilesystemCacheEvictedFileSegmentsDuringPriorityIncrease | Number of file segments evicted from filesystem cache when increasing priority of file segments (Applies to SLRU cache policy) | | FilesystemCacheEvictionReusedIterator | Number of filesystem cache iterator reusing | | FilesystemCacheEvictionSkippedEvictingFileSegments | Number of file segments skipped for eviction because of being in evicting state | | FilesystemCacheEvictionSkippedFileSegments | Number of file segments skipped for eviction because of being in unreleasable state | | FilesystemCacheEvictionSkippedMovingFileSegments | Number of file segments skipped for eviction because of being in moving state | | FilesystemCacheEvictionTries | Number of filesystem cache eviction attempts | | FilesystemCacheFailToReserveSpaceBecauseOfCacheResize | Number of times space reservation was skipped due to the cache is being resized | | FilesystemCacheFailToReserveSpaceBecauseOfLockContention | Number of times space reservation was skipped due to a high contention on the cache lock | | FilesystemCacheFailedEvictionCandidates | Number of file segments which unexpectedly failed to be evicted during dynamic filesystem cache eviction | | FilesystemCacheFreeSpaceKeepingThreadRun | Number of times background thread executed free space keeping job | | FilesystemCacheFreeSpaceKeepingThreadWorkMilliseconds | Time for which background thread executed free space keeping job | | FilesystemCacheGetMicroseconds | Filesystem cache get() time | | FilesystemCacheGetOrSetMicroseconds | Filesystem cache getOrSet() time | | FilesystemCacheHoldFileSegments | Filesystem cache file segments count, which were hold | | FilesystemCacheLoadMetadataMicroseconds | Time spent loading filesystem cache metadata | | FilesystemCacheLockKeyMicroseconds | Lock cache key time | | FilesystemCacheLockMetadataMicroseconds | Lock filesystem cache metadata time | | FilesystemCachePriorityReadLockMicroseconds | Lock filesystem cache time for read in priority queue | | FilesystemCachePriorityWriteLockMicroseconds | Lock filesystem cache time for write to priority queue | | FilesystemCacheReserveAttempts | Filesystem cache space reservation attempt | | FilesystemCacheReserveMicroseconds | Filesystem cache space reservation time | | FilesystemCacheStateLockMicroseconds | Lock filesystem cache time for state lock | | FilesystemCacheUnusedHoldFileSegments | Filesystem cache file segments count, which were hold, but not used (because of seek or LIMIT n, etc) | | FilterPartsByVirtualColumnsMicroseconds | Total time spent in filterPartsByVirtualColumns function. | | FilterTransformPassedBytes | Number of bytes that passed the filter in the query | | FilterTransformPassedRows | Number of rows that passed the filter in the query | | FilteringMarksWithPrimaryKeyMicroseconds | Time spent filtering parts by PK. | | FilteringMarksWithSecondaryKeysMicroseconds | Time spent filtering parts by skip indexes. | | FunctionExecute | Number of SQL ordinary function calls (SQL functions are called on per-block basis, so this number represents the number of blocks). | | GatheredColumns | Number of columns gathered during the vertical stage of merges. | | GatheringColumnMilliseconds | Total time spent while gathering columns for vertical merge | | GlobalThreadPoolExpansions | Counts the total number of times new threads have been added to the global thread pool. This metric indicates the frequency of expansions in the global thread pool to accommodate increased processing demands. | | GlobalThreadPoolJobWaitTimeMicroseconds | Measures the elapsed time from when a job is scheduled in the thread pool to when it is picked up for execution by a worker thread. This metric helps identify delays in job processing, indicating the responsiveness of the thread pool to new tasks. | | GlobalThreadPoolJobs | Counts the number of jobs that have been pushed to the global thread pool. | | GlobalThreadPoolLockWaitMicroseconds | Total time threads have spent waiting for locks in the global thread pool. | | GlobalThreadPoolShrinks | Counts the total number of times the global thread pool has shrunk by removing threads. This occurs when the number of idle threads exceeds max_thread_pool_free_size, indicating adjustments in the global thread pool size in response to decreased thread utilization. | | GlobalThreadPoolThreadCreationMicroseconds | Total time spent waiting for new threads to start. | | HTTPConnectionsCreated | Number of created client HTTP connections | | HTTPConnectionsElapsedMicroseconds | Total time spend on creating client HTTP connections | | HTTPConnectionsErrors | Number of cases when creation of a client HTTP connection failed | | HTTPConnectionsExpired | Number of expired client HTTP connections | | HTTPConnectionsPreserved | Number of preserved client HTTP connections | | HTTPConnectionsReset | Number of reset client HTTP connections | | HTTPConnectionsReused | Number of reused client HTTP connections | | HTTPServerConnectionsClosed | Number of closed server HTTP connections. Keep alive has not been negotiated | | HTTPServerConnectionsCreated | Number of created server HTTP connections | | HTTPServerConnectionsExpired | Number of expired server HTTP connections. | | HTTPServerConnectionsPreserved | Number of preserved server HTTP connections. Connection kept alive successfully | | HTTPServerConnectionsReset | Number of reset server HTTP connections. Server closes connection | | HTTPServerConnectionsReused | Number of reused server HTTP connections | | HardPageFaults | The number of hard page faults in query execution threads. High values indicate either that you forgot to turn off swap on your server, or eviction of memory pages of the ClickHouse binary during very high memory pressure, or successful usage of the 'mmap' read method for the tables data. | | HashJoinPreallocatedElementsInHashTables | How many elements were preallocated in hash tables for hash join. | | HedgedRequestsChangeReplica | Total count when timeout for changing replica expired in hedged requests. | | IOBufferAllocBytes | Number of bytes allocated for IO buffers (for ReadBuffer/WriteBuffer). | | IOBufferAllocs | Number of allocations of IO buffers (for ReadBuffer/WriteBuffer). | | IOUringCQEsCompleted | Total number of successfully completed io_uring CQEs | | IOUringCQEsFailed | Total number of completed io_uring CQEs with failures | | IOUringSQEsResubmitsAsync | Total number of asynchronous io_uring SQE resubmits performed | | IOUringSQEsResubmitsSync | Total number of synchronous io_uring SQE resubmits performed | | IOUringSQEsSubmitted | Total number of io_uring SQEs submitted | | IcebergIteratorInitializationMicroseconds | Total time spent on synchronous initialization of iceberg data iterators. | | IcebergMetadataFilesCacheHits | Number of times iceberg metadata files have been found in the cache. | | IcebergMetadataFilesCacheMisses | Number of times iceberg metadata files have not been found in the iceberg metadata cache and had to be read from (remote) disk. | | IcebergMetadataFilesCacheWeightLost | Approximate number of bytes evicted from the iceberg metadata cache. | | IcebergMetadataReadWaitTimeMicroseconds | Total time data readers spend waiting for iceberg metadata files to be read and parsed, summed across all reader threads. | | IcebergMetadataReturnedObjectInfos | Total number of returned object infos from iceberg iterator. | | IcebergMetadataUpdateMicroseconds | Total time spent on synchronous initialization of iceberg data iterators. | | IcebergMinMaxIndexPrunedFiles | Number of skipped files by using MinMax index in Iceberg | | IcebergMinMaxNonPrunedDeleteFiles | Total number of accepted data files-position delete file pairs by minmax analysis from pairs suitable by partitioning and sequence number. | | IcebergMinMaxPrunedDeleteFiles | Total number of accepted data files-position delete file pairs by minmax analysis from pairs suitable by partitioning and sequence number. | | IcebergPartitionPrunedFiles | Number of skipped files during Iceberg partition pruning | | IcebergTrivialCountOptimizationApplied | Trivial count optimization applied while reading from Iceberg | | IcebergVersionHintUsed | Number of times version-hint.text has been used. | | IgnoredColdParts | See setting ignore_cold_parts_seconds. Number of times read queries ignored very new parts that weren't pulled into cache by CacheWarmer yet. | | IndexAnalysisRounds | Number of times index analysis was performed within the query. | | IndexBinarySearchAlgorithm | Number of times the binary search algorithm is used over the index marks | | IndexGenericExclusionSearchAlgorithm | Number of times the generic exclusion search algorithm is used over the index marks | | InitialQuery | Same as Query, but only counts initial queries (see is_initial_query). | | InitialSelectQuery | Same as InitialQuery, but only for SELECT queries. | | InsertQueriesWithSubqueries | Count INSERT queries with all subqueries | | InsertQuery | Same as Query, but only for INSERT queries. | | InsertQueryTimeMicroseconds | Total time of INSERT queries. | | InsertedBytes | Number of bytes (uncompressed; for columns as they stored in memory) INSERTed to all tables. | | InsertedCompactParts | Number of parts inserted in Compact format. | | InsertedRows | Number of rows INSERTed to all tables. | | InsertedWideParts | Number of parts inserted in Wide format. | | InterfaceHTTPReceiveBytes | Number of bytes received through HTTP interfaces | | InterfaceHTTPSendBytes | Number of bytes sent through HTTP interfaces | | InterfaceInterserverReceiveBytes | Number of bytes received through interserver interfaces | | InterfaceInterserverSendBytes | Number of bytes sent through interserver interfaces | | InterfaceMySQLReceiveBytes | Number of bytes received through MySQL interfaces | | InterfaceMySQLSendBytes | Number of bytes sent through MySQL interfaces | | InterfaceNativeReceiveBytes | Number of bytes received through native interfaces | | InterfaceNativeSendBytes | Number of bytes sent through native interfaces | | InterfacePostgreSQLReceiveBytes | Number of bytes received through PostgreSQL interfaces | | InterfacePostgreSQLSendBytes | Number of bytes sent through PostgreSQL interfaces | | InterfacePrometheusReceiveBytes | Number of bytes received through Prometheus interfaces | | InterfacePrometheusSendBytes | Number of bytes sent through Prometheus interfaces | | JemallocFailedAllocationSampleTracking | Total number of times tracking of jemalloc allocation sample failed | | JemallocFailedDeallocationSampleTracking | Total number of times tracking of jemalloc deallocation sample failed | | JoinBuildTableRowCount | Total number of rows in the build table for a JOIN operation. | | JoinOptimizeMicroseconds | Total time spent executing JOIN plan optimizations. | | JoinProbeTableRowCount | Total number of rows in the probe table for a JOIN operation. | | JoinReorderMicroseconds | Total time spent executing JOIN reordering algorithm. | | JoinResultRowCount | Total number of rows in the result of a JOIN operation. | | KafkaBackgroundReads | Number of background reads populating materialized views from Kafka since server start | | KafkaCommitFailures | Number of failed commits of consumed offsets to Kafka (usually is a sign of some data duplication) | | KafkaCommits | Number of successful commits of consumed offsets to Kafka (normally should be the same as KafkaBackgroundReads) | | KafkaConsumerErrors | Number of errors reported by librdkafka during polls | | KafkaDirectReads | Number of direct selects from Kafka tables since server start | | KafkaMVNotReady | Number of failed attempts to stream data to a materialized view that is not ready | | KafkaMessagesFailed | Number of Kafka messages ClickHouse failed to parse | | KafkaMessagesPolled | Number of Kafka messages polled from librdkafka to ClickHouse | | KafkaMessagesProduced | Number of messages produced to Kafka | | KafkaMessagesRead | Number of Kafka messages already processed by ClickHouse | | KafkaProducerErrors | Number of errors during producing the messages to Kafka | | KafkaProducerFlushes | Number of explicit flushes to Kafka producer | | KafkaRebalanceAssignments | Number of partition assignments (the final stage of consumer group rebalance) | | KafkaRebalanceErrors | Number of failed consumer group rebalances | | KafkaRebalanceRevocations | Number of partition revocations (the first stage of consumer group rebalance) | | KafkaRowsRead | Number of rows parsed from Kafka messages | | KafkaRowsRejected | Number of parsed rows which were later rejected (due to rebalances / errors or similar reasons). Those rows will be consumed again after the rebalance. | | KafkaRowsWritten | Number of rows inserted into Kafka tables | | KafkaWrites | Number of writes (inserts) to Kafka tables | | KeeperAddWatchRequest | Number of add watches requests | | KeeperBatchMaxCount | Number of times the size of batch was limited by the amount | | KeeperBatchMaxTotalSize | Number of times the size of batch was limited by the total bytes size | | KeeperChangelogFileSyncMicroseconds | Time spent in fsync for Keeper changelog (uncompressed logs only) | | KeeperChangelogWrittenBytes | Number of bytes written to the changelog in Keeper | | KeeperCheckRequest | Number of check requests | | KeeperCheckWatchRequest | Number of remove watches requests | | KeeperCommitWaitElapsedMicroseconds | Time spent waiting for certain log to be committed | | KeeperCommits | Number of successful commits | | KeeperCommitsFailed | Number of failed commits | | KeeperCreateRequest | Number of create requests | | KeeperExistsRequest | Number of exists requests | | KeeperGetRequest | Number of get requests | | KeeperLatency | Keeper latency | | KeeperListRequest | Number of list requests | | KeeperLogsEntryReadFromCommitCache | Number of log entries in Keeper being read from commit logs cache | | KeeperLogsEntryReadFromFile | Number of log entries in Keeper being read directly from the changelog file | | KeeperLogsEntryReadFromLatestCache | Number of log entries in Keeper being read from latest logs cache | | KeeperLogsPrefetchedEntries | Number of log entries in Keeper being prefetched from the changelog file | | KeeperMultiReadRequest | Number of multi read requests | | KeeperMultiRequest | Number of multi requests | | KeeperPacketsReceived | Packets received by keeper server | | KeeperPacketsSent | Packets sent by keeper server | | KeeperPreprocessElapsedMicroseconds | Keeper preprocessing latency for a single reuquest | | KeeperProcessElapsedMicroseconds | Keeper commit latency for a single request | | KeeperReadSnapshot | Number of snapshot read(serialization) | | KeeperReconfigRequest | Number of reconfig requests | | KeeperRemoveRequest | Number of remove requests | | KeeperRemoveWatchRequest | Number of remove watches requests | | KeeperRequestRejectedDueToSoftMemoryLimitCount | Number requests that have been rejected due to soft memory limit exceeded | | KeeperRequestTotal | Total requests number on keeper server | | KeeperRequestTotalWithSubrequests | Total requests number on keeper server, counting each subrequest within a multi request | | KeeperSaveSnapshot | Number of snapshot save | | KeeperSetRequest | Number of set requests | | KeeperSetWatchesRequest | Number of set watches requests | | KeeperSnapshotApplys | Number of snapshot applying | | KeeperSnapshotApplysFailed | Number of failed snapshot applying | | KeeperSnapshotCreations | Number of snapshots creations | | KeeperSnapshotCreationsFailed | Number of failed snapshot creations | | KeeperSnapshotFileSyncMicroseconds | Time spent in fsync for Keeper snapshot files | | KeeperSnapshotWrittenBytes | Number of bytes written to snapshot files in Keeper | | KeeperStorageLockWaitMicroseconds | Time spent waiting for acquiring Keeper storage lock | | KeeperTotalElapsedMicroseconds | Keeper total latency for a single request | | LoadedDataParts | Number of data parts loaded by MergeTree tables during initialization. | | LoadedDataPartsMicroseconds | Microseconds spent by MergeTree tables for loading data parts during initialization. | | LoadedMarksCount | Number of marks loaded (total across columns). | | LoadedMarksFiles | Number of mark files loaded. | | LoadedMarksMemoryBytes | Size of in-memory representations of loaded marks. | | LoadedPrimaryIndexBytes | Number of rows of primary key loaded. | | LoadedPrimaryIndexFiles | Number of primary index files loaded. | | LoadedPrimaryIndexRows | Number of rows of primary key loaded. | | LoadedStatisticsMicroseconds | Elapsed time of loading statistics from parts | | LoadingMarksTasksCanceled | Number of times background tasks for loading marks were canceled | | LocalReadThrottlerBytes | Bytes passed through 'max_local_read_bandwidth_for_server'/'max_local_read_bandwidth' throttler. | | LocalReadThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_local_read_bandwidth_for_server'/'max_local_read_bandwidth' throttling. | | LocalThreadPoolBusyMicroseconds | Total time threads have spent executing the actual work. | | LocalThreadPoolExpansions | Counts the total number of times threads have been borrowed from the global thread pool to expand local thread pools. | | LocalThreadPoolJobWaitTimeMicroseconds | Measures the elapsed time from when a job is scheduled in the thread pool to when it is picked up for execution by a worker thread. This metric helps identify delays in job processing, indicating the responsiveness of the thread pool to new tasks. | | LocalThreadPoolJobs | Counts the number of jobs that have been pushed to the local thread pools. | | LocalThreadPoolLockWaitMicroseconds | Total time threads have spent waiting for locks in the local thread pools. | | LocalThreadPoolShrinks | Counts the total number of times threads have been returned to the global thread pool from local thread pools. | | LocalThreadPoolThreadCreationMicroseconds | Total time local thread pools have spent waiting to borrow a thread from the global pool. | | LocalWriteThrottlerBytes | Bytes passed through 'max_local_write_bandwidth_for_server'/'max_local_write_bandwidth' throttler. | | LocalWriteThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_local_write_bandwidth_for_server'/'max_local_write_bandwidth' throttling. | | LogDebug | Number of log messages with level Debug | | LogError | Number of log messages with level Error | | LogFatal | Number of log messages with level Fatal | | LogInfo | Number of log messages with level Info | | LogTest | Number of log messages with level Test | | LogTrace | Number of log messages with level Trace | | LogWarning | Number of log messages with level Warning | | LoggerElapsedNanoseconds | Cumulative time spend in logging | | MMappedFileCacheHits | Number of times a file has been found in the MMap cache (for the 'mmap' read_method), so we didn't have to mmap it again. | | MMappedFileCacheMisses | Number of times a file has not been found in the MMap cache (for the 'mmap' read_method), so we had to mmap it again. | | MainConfigLoads | Number of times the main configuration was reloaded. | | MarkCacheEvictedBytes | Number of bytes evicted from the mark cache. | | MarkCacheEvictedFiles | Number of mark files evicted from the mark cache. | | MarkCacheEvictedMarks | Number of marks evicted from the mark cache. | | MarkCacheHits | Number of times an entry has been found in the mark cache, so we didn't have to load a mark file. | | MarkCacheMisses | Number of times an entry has not been found in the mark cache, so we had to load a mark file in memory, which is a costly operation, adding to query latency. | | MarksTasksFromCache | Number of times marks were loaded synchronously because they were already present in the cache. | | MemoryAllocatedWithoutCheck | Number of times memory has been allocated without checking for memory constraints. | | MemoryAllocatedWithoutCheckBytes | Amount of bytes that has been allocated without checking for memory constraints. | | MemoryAllocatorPurge | Total number of times memory allocator purge was requested | | MemoryAllocatorPurgeTimeMicroseconds | Total time spent for memory allocator purge | | MemoryOvercommitWaitTimeMicroseconds | Total time spent in waiting for memory to be freed in OvercommitTracker. | | MemoryWorkerRun | Number of runs done by MemoryWorker in background | | MemoryWorkerRunElapsedMicroseconds | Total time spent by MemoryWorker for background work | | Merge | Number of launched background merges. | | MergeExecuteMilliseconds | Total busy time spent for execution of background merges | | MergeHorizontalStageExecuteMilliseconds | Total busy time spent for execution of horizontal stage of background merges | | MergeHorizontalStageTotalMilliseconds | Total time spent for horizontal stage of background merges | | MergeMutateBackgroundExecutorTaskCancelMicroseconds | Time spent in cancel() for MergeMutate executor tasks. | | MergeMutateBackgroundExecutorTaskExecuteStepMicroseconds | Time spent in executeStep() for MergeMutate executor tasks. | | MergeMutateBackgroundExecutorTaskResetMicroseconds | Time spent resetting task for MergeMutate executor. | | MergeMutateBackgroundExecutorWaitMicroseconds | Time spent waiting for completion in MergeMutate executor. | | MergePrewarmStageExecuteMilliseconds | Total busy time spent for execution of prewarm stage of background merges | | MergePrewarmStageTotalMilliseconds | Total time spent for prewarm stage of background merges | | MergeProjectionStageExecuteMilliseconds | Total busy time spent for execution of projection stage of background merges | | MergeProjectionStageTotalMilliseconds | Total time spent for projection stage of background merges | | MergeSourceParts | Number of source parts scheduled for merges. | | MergeTextIndexStageExecuteMilliseconds | Total busy time spent for execution of text index stage of background merges | | MergeTextIndexStageTotalMilliseconds | Total time spent for text index stage of background merges | | MergeTotalMilliseconds | Total time spent for background merges | | MergeTreeAllRangesAnnouncementsSent | The number of announcements sent from the remote server to the initiator server about the set of data parts (for MergeTree tables). Measured on the remote server side. | | MergeTreeAllRangesAnnouncementsSentElapsedMicroseconds | Time spent in sending the announcement from the remote server to the initiator server about the set of data parts (for MergeTree tables). Measured on the remote server side. | | MergeTreeDataProjectionWriterBlocks | Number of blocks INSERTed to MergeTree tables projection. Each block forms a data part of level zero. | | MergeTreeDataProjectionWriterBlocksAlreadySorted | Number of blocks INSERTed to MergeTree tables projection that appeared to be already sorted. | | MergeTreeDataProjectionWriterCompressedBytes | Bytes written to filesystem for data INSERTed to MergeTree tables projection. | | MergeTreeDataProjectionWriterMergingBlocksMicroseconds | Time spent merging blocks | | MergeTreeDataProjectionWriterRows | Number of rows INSERTed to MergeTree tables projection. | | MergeTreeDataProjectionWriterSortingBlocksMicroseconds | Time spent sorting blocks (for projection it might be a key different from table's sorting key) | | MergeTreeDataProjectionWriterUncompressedBytes | Uncompressed bytes (for columns as they stored in memory) INSERTed to MergeTree tables projection. | | MergeTreeDataWriterBlocks | Number of blocks INSERTed to MergeTree tables. Each block forms a data part of level zero. | | MergeTreeDataWriterBlocksAlreadySorted | Number of blocks INSERTed to MergeTree tables that appeared to be already sorted. | | MergeTreeDataWriterCompressedBytes | Bytes written to filesystem for data INSERTed to MergeTree tables. | | MergeTreeDataWriterMergingBlocksMicroseconds | Time spent merging input blocks (for special MergeTree engines) | | MergeTreeDataWriterProjectionsCalculationMicroseconds | Time spent calculating projections | | MergeTreeDataWriterRows | Number of rows INSERTed to MergeTree tables. | | MergeTreeDataWriterSkipIndicesCalculationMicroseconds | Time spent calculating skip indices | | MergeTreeDataWriterSortingBlocksMicroseconds | Time spent sorting blocks | | MergeTreeDataWriterStatisticsCalculationMicroseconds | Time spent calculating statistics | | MergeTreeDataWriterUncompressedBytes | Uncompressed bytes (for columns as they stored in memory) INSERTed to MergeTree tables. | | MergeTreePrefetchedReadPoolInit | Time spent preparing tasks in MergeTreePrefetchedReadPool | | MergeTreeReadTaskRequestsReceived | The number of callbacks requested from the remote server back to the initiator server to choose the read task (for MergeTree tables). Measured on the initiator server side. | | MergeTreeReadTaskRequestsSent | The number of callbacks requested from the remote server back to the initiator server to choose the read task (for MergeTree tables). Measured on the remote server side. | | MergeTreeReadTaskRequestsSentElapsedMicroseconds | Time spent in callbacks requested from the remote server back to the initiator server to choose the read task (for MergeTree tables). Measured on the remote server side. | | MergeVerticalStageExecuteMilliseconds | Total busy time spent for execution of vertical stage of background merges | | MergeVerticalStageTotalMilliseconds | Total time spent for vertical stage of background merges | | MergeWrittenRows | Number of rows written during the merge. | | MergedColumns | Number of columns merged during the horizontal stage of merges. | | MergedIntoCompactParts | Number of parts merged into Compact format. | | MergedIntoWideParts | Number of parts merged into Wide format. | | MergedRows | Rows read for background merges. This is the number of rows before merge. | | MergedUncompressedBytes | Uncompressed bytes (for columns as they stored in memory) that was read for background merges. This is the number before merge. | | MergerMutatorPartsInRangesForMergeCount | Amount of candidate parts for merge | | MergerMutatorPrepareRangesForMergeElapsedMicroseconds | Time spent to prepare parts ranges which can be merged according to merge predicate. | | MergerMutatorRangesForMergeCount | Amount of candidate ranges for merge | | MergerMutatorSelectPartsForMergeElapsedMicroseconds | Time spent to select parts from ranges which can be merged. | | MergerMutatorSelectRangePartsCount | Amount of parts in selected range for merge | | MergerMutatorsGetPartsForMergeElapsedMicroseconds | Time spent to take data parts snapshot to build ranges from them. | | MergesRejectedByMemoryLimit | Number of background merges rejected due to memory limit | | MergesThrottlerBytes | Bytes passed through 'max_merges_bandwidth_for_server' throttler. | | MergesThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_merges_bandwidth_for_server' throttling. | | MergingSortedMilliseconds | Total time spent while merging sorted columns | | MetadataFromKeeperBackgroundCleanupBlobs | Number of times an empty blob layout part was cleaned up by background task | | MetadataFromKeeperBackgroundCleanupErrors | Number of times an error was encountered in background cleanup task | | MetadataFromKeeperBackgroundCleanupObjects | Number of times a old deleted object clean up was performed by background task | | MetadataFromKeeperBackgroundCleanupTransactions | Number of times old transaction idempotency token was cleaned up by background task | | MetadataFromKeeperCacheHit | Number of times an object storage metadata request was answered from cache without making request to Keeper | | MetadataFromKeeperCacheMiss | Number of times an object storage metadata request had to be answered from Keeper | | MetadataFromKeeperCacheTooManyInvalidated | Number of times filesystem cache returned too many invalidated entries | | MetadataFromKeeperCacheUpdateMicroseconds | Total time spent in updating the cache including waiting for responses from Keeper | | MetadataFromKeeperCleanupTransactionCommit | Number of times metadata transaction commit for deleted objects cleanup was attempted | | MetadataFromKeeperCleanupTransactionCommitRetry | Number of times metadata transaction commit for deleted objects cleanup was retried | | MetadataFromKeeperIndividualOperations | Number of paths read or written by single or multi requests to Keeper | | MetadataFromKeeperIndividualOperationsMicroseconds | Time spend during single or multi requests to Keeper | | MetadataFromKeeperOperations | Number of times a request was made to Keeper | | MetadataFromKeeperReconnects | Number of times a reconnect to Keeper was done | | MetadataFromKeeperTransactionCommit | Number of times metadata transaction commit was attempted | | MetadataFromKeeperTransactionCommitRetry | Number of times metadata transaction commit was retried | | MetadataFromKeeperUpdateCacheOneLevel | Number of times a cache update for one level of directory tree was done | | MoveBackgroundExecutorTaskCancelMicroseconds | Time spent in cancel() for Move executor tasks. | | MoveBackgroundExecutorTaskExecuteStepMicroseconds | Time spent in executeStep() for Move executor tasks. | | MoveBackgroundExecutorTaskResetMicroseconds | Time spent resetting task for Move executor. | | MoveBackgroundExecutorWaitMicroseconds | Time spent waiting for completion in Move executor. | | MutateTaskProjectionsCalculationMicroseconds | Time spent calculating projections in mutations | | MutatedRows | Rows read for mutations. This is the number of rows before mutation | | MutatedUncompressedBytes | Uncompressed bytes (for columns as they stored in memory) that was read for mutations. This is the number before mutation. | | MutationAffectedRowsUpperBound | The upper bound of number of rows that were affected by mutation (e.g. number of rows that satisfy the predicate of UPDATE or DELETE mutation). The actual number may be slightly less | | MutationAllPartColumns | Number of times when task to mutate all columns in part was created | | MutationCreatedEmptyParts | Number of total parts which were replaced to empty parts instead of running mutation | | MutationExecuteMilliseconds | Total busy time spent for execution of mutations. | | MutationSomePartColumns | Number of times when task to mutate some columns in part was created | | MutationTotalMilliseconds | Total time spent for mutations. | | MutationTotalParts | Number of total parts for which mutations tried to be applied | | MutationUntouchedParts | Number of total parts for which mutations tried to be applied but which was completely skipped according to predicate | | MutationsAppliedOnFlyInAllReadTasks | Total number of applied mutations on-fly among all read tasks | | MutationsThrottlerBytes | Bytes passed through 'max_mutations_bandwidth_for_server' throttler. | | MutationsThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_mutations_bandwidth_for_server' throttling. | | NaiveBayesClassifierModelsAllocatedBytes | Number of bytes allocated for Naive Bayes Classifier models. | | NaiveBayesClassifierModelsLoaded | Number of Naive Bayes Classifier models loaded. | | NetworkReceiveBytes | Total number of bytes received from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries. | | NetworkReceiveElapsedMicroseconds | Total time spent waiting for data to receive or receiving data from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries. | | NetworkSendBytes | Total number of bytes send to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries. | | NetworkSendElapsedMicroseconds | Total time spent waiting for data to send to network or sending data to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries. | | NotCreatedLogEntryForMerge | Log entry to merge parts in ReplicatedMergeTree is not created due to concurrent log update by another replica. | | NotCreatedLogEntryForMutation | Log entry to mutate parts in ReplicatedMergeTree is not created due to concurrent log update by another replica. | | OSCPUVirtualTimeMicroseconds | CPU time spent seen by OS. Does not include involuntary waits due to virtualization. | | OSCPUWaitMicroseconds | Total time a thread was ready for execution but waiting to be scheduled by OS, from the OS point of view. | | OSIOWaitMicroseconds | Total time a thread spent waiting for a result of IO operation, from the OS point of view. This is real IO that doesn't include page cache. | | OSReadBytes | Number of bytes read from disks or block devices. Doesn't include bytes read from page cache. May include excessive data due to block size, readahead, etc. | | OSReadChars | Number of bytes read from filesystem, including page cache, as well as network and other files. | | OSWriteBytes | Number of bytes written to disks or block devices. Doesn't include bytes that are in page cache dirty pages. May not include data that was written by OS asynchronously. | | OSWriteChars | Number of bytes written to filesystem, including page cache, as well as network and other files. | | ObjectStorageQueueCancelledFiles | Number cancelled files in StorageS3(Azure)Queue | | ObjectStorageQueueCleanupMaxSetSizeOrTTLMicroseconds | Time spent to set file as failed | | ObjectStorageQueueCommitRequests | Number of keeper requests to commit files as either failed or processed | | ObjectStorageQueueExceptionsDuringInsert | Number of exceptions during insert in S3(Azure)Queue | | ObjectStorageQueueExceptionsDuringRead | Number of exceptions during read in S3(Azure)Queue | | ObjectStorageQueueFailedFiles | Number of files which failed to be processed | | ObjectStorageQueueFailedToBatchSetProcessing | Number of times batched set processing request failed | | ObjectStorageQueueFilteredFiles | Number of filtered files in StorageS3(Azure)Queue | | ObjectStorageQueueInsertIterations | Number of insert iterations | | ObjectStorageQueueListedFiles | Number of listed files in StorageS3(Azure)Queue | | ObjectStorageQueueMovedObjects | Number of objects moved as part of after_processing = move | | ObjectStorageQueueProcessedFiles | Number of files which were processed | | ObjectStorageQueueProcessedRows | Number of processed rows in StorageS3(Azure)Queue | | ObjectStorageQueuePullMicroseconds | Time spent to read file data | | ObjectStorageQueueReadBytes | Number of read bytes (not equal to the number of actually inserted bytes) | | ObjectStorageQueueReadFiles | Number of read files (not equal to the number of actually inserted files) | | ObjectStorageQueueReadRows | Number of read rows (not equal to the number of actually inserted rows) | | ObjectStorageQueueRemovedObjects | Number of objects removed as part of after_processing = delete | | ObjectStorageQueueSuccessfulCommits | Number of successful keeper commits | | ObjectStorageQueueTaggedObjects | Number of objects tagged as part of after_processing = tag | | ObjectStorageQueueTrySetProcessingFailed | The number of times we unsuccessfully set file as processing | | ObjectStorageQueueTrySetProcessingRequests | The number of times we tried to make set processing request | | ObjectStorageQueueTrySetProcessingSucceeded | The number of times we successfully set file as processing | | ObjectStorageQueueUnsuccessfulCommits | Number of unsuccessful keeper commits | | ObsoleteReplicatedParts | Number of times a data part was covered by another data part that has been fetched from a replica (so, we have marked a covered data part as obsolete and no longer needed). | | OpenedFileCacheHits | Number of times a file has been found in the opened file cache, so we didn't have to open it again. | | OpenedFileCacheMicroseconds | Amount of time spent executing OpenedFileCache methods. | | OpenedFileCacheMisses | Number of times a file has been found in the opened file cache, so we had to open it again. | | OtherQueryTimeMicroseconds | Total time of queries that are not SELECT or INSERT. | | OverflowAny | Number of times approximate GROUP BY was in effect: when aggregation was performed only on top of first 'max_rows_to_group_by' unique keys and other keys were ignored due to 'group_by_overflow_mode' = 'any'. | | OverflowBreak | Number of times, data processing was cancelled by query complexity limitation with setting '_overflow_mode' = 'break' and the result is incomplete. | | OverflowThrow | Number of times, data processing was cancelled by query complexity limitation with setting 'overflow_mode' = 'throw' and exception was thrown. | | PageCacheHits | Number of times a block of data has been found in the userspace page cache. | | PageCacheMisses | Number of times a block of data has not been found in the userspace page cache. | | PageCacheOvercommitResize | Number of times the userspace page cache was auto-resized to free memory during a memory allocation. | | PageCacheReadBytes | Number of bytes read from userspace page cache. | | PageCacheResized | Number of times the userspace page cache was auto-resized (typically happens a few times per second, controlled by memory_worker_period_ms). | | PageCacheWeightLost | Number of bytes evicted from the userspace page cache | | ParallelReplicasAnnouncementMicroseconds | Time spent to send an announcement | | ParallelReplicasAvailableCount | Number of replicas available to execute a query with task-based parallel replicas | | ParallelReplicasCollectingOwnedSegmentsMicroseconds | Time spent collecting segments meant by hash | | ParallelReplicasDeniedRequests | Number of completely denied requests to the initiator | | ParallelReplicasHandleAnnouncementMicroseconds | Time spent processing replicas announcements | | ParallelReplicasHandleRequestMicroseconds | Time spent processing requests for marks from replicas | | ParallelReplicasNumRequests | Number of requests to the initiator. | | ParallelReplicasProcessingPartsMicroseconds | Time spent processing data parts | | ParallelReplicasQueryCount | Number of (sub)queries executed using parallel replicas during a query execution | | ParallelReplicasReadAssignedForStealingMarks | Sum across all replicas of how many of scheduled marks were assigned for stealing by consistent hash | | ParallelReplicasReadAssignedMarks | Sum across all replicas of how many of scheduled marks were assigned by consistent hash | | ParallelReplicasReadMarks | How many marks were read by the given replica | | ParallelReplicasReadRequestMicroseconds | Time spent for read requests | | ParallelReplicasReadUnassignedMarks | Sum across all replicas of how many unassigned marks were scheduled | | ParallelReplicasStealingByHashMicroseconds | Time spent collecting segments meant for stealing by hash | | ParallelReplicasStealingLeftoversMicroseconds | Time spent collecting orphaned segments | | ParallelReplicasUnavailableCount | Number of replicas which was chosen, but found to be unavailable during query execution with task-based parallel replicas | | ParallelReplicasUsedCount | Number of replicas used to execute a query with task-based parallel replicas | | ParquetColumnsFilterExpression | The total number of columns that were passed through filter | | ParquetDecodingTaskBatches | Task groups sent to a thread pool by parquet reader | | ParquetDecodingTasks | Tasks issued by parquet reader | | ParquetFetchWaitTimeMicroseconds | Time of waiting for parquet file reads from decoding threads (not prefetching threads) | | ParquetMetadataCacheHits | Number of times parquet metadata has been found in the cache. | | ParquetMetadataCacheMisses | Number of times parquet metadata has not been found in the cache and had to be read from disk. | | ParquetMetadataCacheWeightLost | Approximate number of bytes evicted from the parquet metadata cache. | | ParquetPrefetcherReadEntireFile | The total number of read with ReadMode::EntireFileIsInMemory by DB::Parquet::Prefetcher | | ParquetPrefetcherReadRandomRead | The total number of reads with ReadMode::RandomRead by DB::Parquet::Prefetcher | | ParquetPrefetcherReadSeekAndRead | The total number of reads with ReadMode::SeekAndRead by DB::Parquet::Prefetcher | | ParquetPrunedRowGroups | The total number of row groups pruned from parquet data | | ParquetReadRowGroups | The total number of row groups read from parquet data | | ParquetRowsFilterExpression | The total number of rows that were passed through filter | | PartsLockHoldMicroseconds | Total time spent holding data parts lock in MergeTree tables | | PartsLockWaitMicroseconds | Total time spent waiting for data parts lock in MergeTree tables | | PartsLocks | Number of times data parts lock has been acquired for MergeTree tables | | PatchesAcquireLockMicroseconds | Total number of microseconds spent to acquire lock for executing lightweight updates | | PatchesAcquireLockTries | Total number of tries to acquire lock for executing lightweight updates | | PatchesAppliedInAllReadTasks | Total number of applied patch parts among all read tasks | | PatchesJoinAppliedInAllReadTasks | Total number of applied patch parts with Join mode among all read tasks | | PatchesJoinRowsAddedToHashTable | Total number of rows added to hash tables when applying patch parts with Join mode | | PatchesMergeAppliedInAllReadTasks | Total number of applied patch parts with Merge mode among all read tasks | | PatchesReadRows | Total number of rows read from patch parts | | PatchesReadUncompressedBytes | Total number of uncompressed bytes read from patch parts | | PerfAlignmentFaults | Number of alignment faults. These happen when unaligned memory accesses happen; the kernel can handle these but it reduces performance. This happens only on some architectures (never on x86). | | PerfBranchInstructions | Retired branch instructions. Prior to Linux 2.6.35, this used the wrong event on AMD processors. | | PerfBranchMisses | Mispredicted branch instructions. | | PerfBusCycles | Bus cycles, which can be different from total cycles. | | PerfCPUClock | The CPU clock, a high-resolution per-CPU timer | | PerfCPUCycles | Total cycles. Be wary of what happens during CPU frequency scaling. | | PerfCPUMigrations | Number of times the process has migrated to a new CPU | | PerfCacheMisses | Cache misses. Usually this indicates Last Level Cache misses; this is intended to be used in conjunction with the PERFCOUNTHWCACHEREFERENCES event to calculate cache miss rates. | | PerfCacheReferences | Cache accesses. Usually, this indicates Last Level Cache accesses, but this may vary depending on your CPU. This may include prefetches and coherency messages; again this depends on the design of your CPU. | | PerfContextSwitches | Number of context switches | | PerfDataTLBMisses | Data TLB misses | | PerfDataTLBReferences | Data TLB references | | PerfEmulationFaults | Number of emulation faults. The kernel sometimes traps on unimplemented instructions and emulates them for user space. This can negatively impact performance. | | PerfInstructionTLBMisses | Instruction TLB misses | | PerfInstructionTLBReferences | Instruction TLB references | | PerfInstructions | Retired instructions. Be careful, these can be affected by various issues, most notably hardware interrupt counts. | | PerfLocalMemoryMisses | Local NUMA node memory read misses | | PerfLocalMemoryReferences | Local NUMA node memory reads | | PerfMinEnabledRunningTime | Running time for event with minimum enabled time. Used to track the amount of event multiplexing | | PerfMinEnabledTime | For all events, minimum time that an event was enabled. Used to track event multiplexing influence | | PerfRefCPUCycles | Total cycles; not affected by CPU frequency scaling. | | PerfStalledCyclesBackend | Stalled cycles during retirement. | | PerfStalledCyclesFrontend | Stalled cycles during issue. | | PerfTaskClock | A clock count specific to the task that is running | | PolygonsAddedToPool | A polygon has been added to the cache (pool) for the 'pointInPolygon' function. | | PolygonsInPoolAllocatedBytes | The number of bytes for polygons added to the cache (pool) for the 'pointInPolygon' function. | | PreferredWarmedUnmergedParts | See setting prefer_warmed_unmerged_parts_seconds. Number of times read queries used outdated pre-merge parts that are in cache instead of merged part that wasn't pulled into cache by CacheWarmer yet. | | PrimaryIndexCacheHits | Number of times an entry has been found in the primary index cache, so we didn't have to load a index file. | | PrimaryIndexCacheMisses | Number of times an entry has not been found in the primary index cache, so we had to load a index file in memory, which is a costly operation, adding to query latency. | | QueriesWithSubqueries | Count queries with all subqueries | | Query | Number of queries to be interpreted and potentially executed. Does not include queries that failed to parse or were rejected due to AST size limits, quota limits or limits on the number of simultaneously running queries. May include internal queries initiated by ClickHouse itself. Does not count subqueries. | | QueryBackupThrottlerBytes | Bytes passed through 'max_backup_bandwidth' throttler. | | QueryBackupThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_backup_bandwidth' throttling. | | QueryCacheAgeSeconds | The sum of ages of found query cache entries in seconds. The value is set both for hits and misses. | | QueryCacheHits | Number of times a query result has been found in the query cache (and query computation was avoided). Only updated for SELECT queries with SETTING use_query_cache = 1. | | QueryCacheMisses | Number of times a query result has not been found in the query cache (and required query computation). Only updated for SELECT queries with SETTING use_query_cache = 1. | | QueryCacheReadBytes | The number of (uncompressed) bytes read from the query cache. | | QueryCacheReadRows | The number of rows read from the query cache. | | QueryCacheWrittenBytes | The number of (uncompressed) bytes saved into the query cache | | QueryCacheWrittenRows | The number of rows saved into the query cache. | | QueryConditionCacheHits | Number of times an entry has been found in the query condition cache (and reading of marks can be skipped). Only updated for SELECT queries with SETTING use_query_condition_cache = 1. | | QueryConditionCacheMisses | Number of times an entry has not been found in the query condition cache (and reading of mark cannot be skipped). Only updated for SELECT queries with SETTING use_query_condition_cache = 1. | | QueryLocalReadThrottlerBytes | Bytes passed through 'max_local_read_bandwidth' throttler. | | QueryLocalReadThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_local_read_bandwidth' throttling. | | QueryLocalWriteThrottlerBytes | Bytes passed through 'max_local_write_bandwidth' throttler. | | QueryLocalWriteThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_local_write_bandwidth' throttling. | | QueryMaskingRulesMatch | Number of times query masking rules was successfully matched. | | QueryMemoryLimitExceeded | Number of times when memory limit exceeded for query. | | QueryPlanOptimizeMicroseconds | Total time spent executing query plan optimizations. | | QueryPreempted | How many times tasks are paused and waiting due to 'priority' setting | | QueryProfilerConcurrencyOverruns | Number of times we drop processing of a query profiler signal due to too many concurrent query profilers in other threads, which may indicate overload. | | QueryProfilerErrors | Invalid memory accesses during asynchronous stack unwinding. | | QueryProfilerRuns | Number of times QueryProfiler had been run. | | QueryProfilerSignalOverruns | Number of times we drop processing of a query profiler signal due to overrun plus the number of signals that OS has not delivered due to overrun. | | QueryRemoteReadThrottlerBytes | Bytes passed through 'max_remote_read_network_bandwidth' throttler. | | QueryRemoteReadThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_remote_read_network_bandwidth' throttling. | | QueryRemoteWriteThrottlerBytes | Bytes passed through 'max_remote_write_network_bandwidth' throttler. | | QueryRemoteWriteThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_remote_write_network_bandwidth' throttling. | | QueryTimeMicroseconds | Total time of all queries. | | QuorumFailedInserts | Number of inserts failed due to quorum not reaching. | | QuorumParts | Number of data parts written with quorum. It counts as one part for sync insert and maybe up to async inserts count for insert which flushes async inserts. | | QuorumWaitMicroseconds | Total time spent waiting for quorum during inserts. | | RWLockAcquiredReadLocks | Number of times a read lock was acquired (in a heavy RWLock). | | RWLockAcquiredWriteLocks | Number of times a write lock was acquired (in a heavy RWLock). | | RWLockReadersWaitMilliseconds | Total time spent waiting for a read lock to be acquired (in a heavy RWLock). | | RWLockWritersWaitMilliseconds | Total time spent waiting for a write lock to be acquired (in a heavy RWLock). | | ReadBackoff | Number of times the number of query processing threads was lowered due to slow reads. | | ReadBufferFromAzureBytes | Bytes read from Azure. | | ReadBufferFromAzureInitMicroseconds | Time spent initializing connection to Azure. | | ReadBufferFromAzureMicroseconds | Time spent on reading from Azure. | | ReadBufferFromAzureRequestsErrors | Number of exceptions while reading from Azure | | ReadBufferFromFileDescriptorRead | Number of reads (read/pread) from a file descriptor. Does not include sockets. | | ReadBufferFromFileDescriptorReadBytes | Number of bytes read from file descriptors. If the file is compressed, this will show the compressed data size. | | ReadBufferFromFileDescriptorReadFailed | Number of times the read (read/pread) from a file descriptor have failed. | | ReadBufferFromS3Bytes | Bytes read from S3. | | ReadBufferFromS3InitMicroseconds | Time spent initializing connection to S3. | | ReadBufferFromS3Microseconds | Time spent on reading from S3. | | ReadBufferFromS3RequestsErrors | Number of exceptions while reading from S3. | | ReadBufferSeekCancelConnection | Number of seeks which lead to new connection (s3, http) | | ReadCompressedBytes | Number of bytes (the number of bytes before decompression) read from compressed sources (files, network). | | ReadPatchesMicroseconds | Total time spent reading patch parts | | ReadTaskRequestsReceived | The number of callbacks requested from the remote server back to the initiator server to choose the read task (for s3Cluster table function and similar). Measured on the initiator server side. | | ReadTaskRequestsSent | The number of callbacks requested from the remote server back to the initiator server to choose the read task (for s3Cluster table function and similar). Measured on the remote server side. | | ReadTaskRequestsSentElapsedMicroseconds | Time spent in callbacks requested from the remote server back to the initiator server to choose the read task (for s3Cluster table function and similar). Measured on the remote server side. | | ReadTasksWithAppliedMutationsOnFly | Total number of read tasks for which there was any mutation applied on fly | | ReadTasksWithAppliedPatches | Total number of read tasks for which there was any patch part applied | | ReadWriteBufferFromHTTPBytes | Total size of payload bytes received and sent by ReadWriteBufferFromHTTP. Doesn't include HTTP headers. | | ReadWriteBufferFromHTTPRequestsSent | Number of HTTP requests sent by ReadWriteBufferFromHTTP | | RealTimeMicroseconds | Total (wall clock) time spent in processing (queries and other tasks) threads (note that this is a sum). | | RefreshableViewLockTableRetry | How many times a SELECT from refreshable materialized view had to switch to a new table because the old table was dropped | | RefreshableViewRefreshFailed | How many times refreshable materialized views failed to refresh | | RefreshableViewRefreshSuccess | How many times refreshable materialized views refreshed | | RefreshableViewSyncReplicaRetry | How many times a SELECT from refreshable materialized view failed and retried an implicit SYNC REPLICA | | RefreshableViewSyncReplicaSuccess | How many times a SELECT from refreshable materialized view did an implicit SYNC REPLICA | | RegexpLocalCacheHit | Number of times we fetched compiled regular expression from a local cache. | | RegexpLocalCacheMiss | Number of times we failed to fetch compiled regular expression from a local cache. | | RegexpWithMultipleNeedlesCreated | Regular expressions with multiple needles (VectorScan library) compiled. | | RegexpWithMultipleNeedlesGlobalCacheHit | Number of times we fetched compiled regular expression with multiple needles (VectorScan library) from the global cache. | | RegexpWithMultipleNeedlesGlobalCacheMiss | Number of times we failed to fetch compiled regular expression with multiple needles (VectorScan library) from the global cache. | | RejectedInserts | Number of times the INSERT of a block to a MergeTree table was rejected with 'Too many parts' exception due to high number of active data parts for partition. | | RejectedLightweightUpdates | Number of time the lightweight update was rejected due to too many uncompressed bytes in patches. | | RejectedMutations | Number of times the mutation of a MergeTree table was rejected with 'Too many mutations' exception due to high number of unfinished mutations for table. | | RemoteFSBuffers | Number of buffers created for asynchronous reading from remote filesystem | | RemoteFSCancelledPrefetches | Number of cancelled prefecthes (because of seek) | | RemoteFSLazySeeks | Number of lazy seeks | | RemoteFSPrefetchedBytes | Number of bytes from prefecthed buffer | | RemoteFSPrefetchedReads | Number of reads from prefecthed buffer | | RemoteFSPrefetches | Number of prefetches made with asynchronous reading from remote filesystem | | RemoteFSSeeks | Total number of seeks for async buffer | | RemoteFSSeeksWithReset | Number of seeks which lead to a new connection | | RemoteFSUnprefetchedBytes | Number of bytes from unprefetched buffer | | RemoteFSUnprefetchedReads | Number of reads from unprefetched buffer | | RemoteFSUnusedPrefetches | Number of prefetches pending at buffer destruction | | RemoteReadThrottlerBytes | Bytes passed through 'max_remote_read_network_bandwidth_for_server'/'max_remote_read_network_bandwidth' throttler. | | RemoteReadThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_remote_read_network_bandwidth_for_server'/'max_remote_read_network_bandwidth' throttling. | | RemoteWriteThrottlerBytes | Bytes passed through 'max_remote_write_network_bandwidth_for_server'/'max_remote_write_network_bandwidth' throttler. | | RemoteWriteThrottlerSleepMicroseconds | Total time a query was sleeping to conform 'max_remote_write_network_bandwidth_for_server'/'max_remote_write_network_bandwidth' throttling. | | ReplacingSortedMilliseconds | Total time spent while replacing sorted columns | | ReplicaPartialShutdown | How many times Replicated table has to deinitialize its state due to session expiration in ZooKeeper. The state is reinitialized every time when ZooKeeper is available again. | | ReplicatedCoveredPartsInZooKeeperOnStart | For debugging purposes. Number of parts in ZooKeeper that have a covering part, but doesn't exist on disk. Checked on server start. | | ReplicatedDataLoss | Number of times a data part that we wanted doesn't exist on any replica (even on replicas that are offline right now). That data parts are definitely lost. This is normal due to asynchronous replication (if quorum inserts were not enabled), when the replica on which the data part was written was failed and when it became online after fail it doesn't contain that data part. | | ReplicatedPartChecks | Number of times we had to perform advanced search for a data part on replicas or to clarify the need of an existing data part. | | ReplicatedPartChecksFailed | Number of times the advanced search for a data part on replicas did not give result or when unexpected part has been found and moved away. | | ReplicatedPartFailedFetches | Number of times a data part was failed to download from replica of a ReplicatedMergeTree table. | | ReplicatedPartFetches | Number of times a data part was downloaded from replica of a ReplicatedMergeTree table. | | ReplicatedPartFetchesOfMerged | Number of times we prefer to download already merged part from replica of ReplicatedMergeTree table instead of performing a merge ourself (usually we prefer doing a merge ourself to save network traffic). This happens when we have not all source parts to perform a merge or when the data part is old enough. | | ReplicatedPartMerges | Number of times data parts of ReplicatedMergeTree tables were successfully merged. | | ReplicatedPartMutations | Number of times data parts of ReplicatedMergeTree tables were successfully mutated. | | RestorePartsSkippedBytes | Total size of files skipped while restoring parts | | RestorePartsSkippedFiles | Number of files skipped while restoring parts | | RowsReadByMainReader | Number of rows read from MergeTree tables by the main reader (after PREWHERE step). | | RowsReadByPrewhereReaders | Number of rows read from MergeTree tables (in total) by prewhere readers. | | RuntimeDataflowStatisticsInputBytes | Collected statistics on the number of bytes replicas would read if the query was executed with parallel replicas | | RuntimeDataflowStatisticsOutputBytes | Collected statistics on the number of bytes replicas would send to the initiator if the query was executed with parallel replicas | | RuntimeFilterBlocksProcessed | Number of blocks processed by JOIN Runtime Filters | | RuntimeFilterBlocksSkipped | Number of blocks skipped by JOIN Runtime Filters without processing due to filter being dynamically disabled because of poor filtering ratio | | RuntimeFilterRowsChecked | Number of rows checked by JOIN Runtime Filters | | RuntimeFilterRowsPassed | Number of rows that passed (not filtered out by) JOIN Runtime Filters | | RuntimeFilterRowsSkipped | Number of rows in blocks that were skipped by JOIN Runtime Filters | | RuntimeFiltersCreated | Number of distinct JOIN Runtime Filters created within a query | | S3AbortMultipartUpload | Number of S3 API AbortMultipartUpload calls. | | S3CachedCredentialsProvidersAdded | Total number of newly added credentials providers to the cache | | S3CachedCredentialsProvidersReused | Total number of reused credentials provider from the cache | | S3Clients | Number of created S3 clients. | | S3CompleteMultipartUpload | Number of S3 API CompleteMultipartUpload calls. | | S3CopyObject | Number of S3 API CopyObject calls. | | S3CreateMultipartUpload | Number of S3 API CreateMultipartUpload calls. | | S3DeleteObjects | Number of S3 API DeleteObject(s) calls. | | S3GetObject | Number of S3 API GetObject calls. | | S3GetObjectTagging | Number of S3 API GetObjectTagging calls. | | S3GetRequestThrottlerBlocked | Number of S3 GET and SELECT requests blocked by throttler. | | S3GetRequestThrottlerCount | Number of S3 GET and SELECT requests passed through throttler: blocked and not blocked. | | S3GetRequestThrottlerSleepMicroseconds | Total time a query was sleeping to conform S3 GET and SELECT request throttling. | | S3HeadObject | Number of S3 API HeadObject calls. | | S3ListObjects | Number of S3 API ListObjects calls. | | S3PutObject | Number of S3 API PutObject calls. | | S3PutRequestThrottlerBlocked | Number of S3 PUT, COPY, POST and LIST requests blocked by throttler. | | S3PutRequestThrottlerCount | Number of S3 PUT, COPY, POST and LIST requests passed through throttler: blocked and not blocked. | | S3PutRequestThrottlerSleepMicroseconds | Total time a query was sleeping to conform S3 PUT, COPY, POST and LIST request throttling. | | S3QueueSetFileFailedMicroseconds | Time spent to set file as failed | | S3QueueSetFileProcessedMicroseconds | Time spent to set file as processed | | S3QueueSetFileProcessingMicroseconds | Time spent to set file as processing | | S3ReadMicroseconds | Time of GET and HEAD requests to S3 storage. | | S3ReadRequestAttempts | Number of attempts for GET and HEAD requests, including the initial try and any retries, but excluding retries performed internally by the S3 retry strategy | | S3ReadRequestRetryableErrors | Number of retryable errors for GET and HEAD requests, excluding retries performed internally by the S3 retry strategy | | S3ReadRequestsCount | Number of GET and HEAD requests to S3 storage. | | S3ReadRequestsErrors | Number of non-throttling errors in GET and HEAD requests to S3 storage. | | S3ReadRequestsRedirects | Number of redirects in GET and HEAD requests to S3 storage. | | S3ReadRequestsThrottling | Number of 429 and 503 errors in GET and HEAD requests to S3 storage. | | S3UploadPart | Number of S3 API UploadPart calls. | | S3UploadPartCopy | Number of S3 API UploadPartCopy calls. | | S3WriteMicroseconds | Time of POST, DELETE, PUT and PATCH requests to S3 storage. | | S3WriteRequestAttempts | Number of attempts for POST, DELETE, PUT and PATCH requests, including the initial try and any retries, but excluding retries performed internally by the retry strategy | | S3WriteRequestRetryableErrors | Number of retryable errors for POST, DELETE, PUT and PATCH requests, excluding retries performed internally by the retry strategy | | S3WriteRequestsCount | Number of POST, DELETE, PUT and PATCH requests to S3 storage. | | S3WriteRequestsErrors | Number of non-throttling errors in POST, DELETE, PUT and PATCH requests to S3 storage. | | S3WriteRequestsRedirects | Number of redirects in POST, DELETE, PUT and PATCH requests to S3 storage. | | S3WriteRequestsThrottling | Number of 429 and 503 errors in POST, DELETE, PUT and PATCH requests to S3 storage. | | ScalarSubqueriesCacheMiss | Number of times a read from a scalar subquery was not cached and had to be calculated completely | | ScalarSubqueriesGlobalCacheHit | Number of times a read from a scalar subquery was done using the global cache | | ScalarSubqueriesLocalCacheHit | Number of times a read from a scalar subquery was done using the local cache | | SchedulerIOReadBytes | Bytes passed through scheduler for IO reads. | | SchedulerIOReadRequests | Resource requests passed through scheduler for IO reads. | | SchedulerIOReadWaitMicroseconds | Total time a query was waiting on resource requests for IO reads. | | SchedulerIOWriteBytes | Bytes passed through scheduler for IO writes. | | SchedulerIOWriteRequests | Resource requests passed through scheduler for IO writes. | | SchedulerIOWriteWaitMicroseconds | Total time a query was waiting on resource requests for IO writes. | | SchemaInferenceCacheEvictions | Number of times a schema from cache was evicted due to overflow | | SchemaInferenceCacheHits | Number of times the requested source is found in schema cache | | SchemaInferenceCacheInvalidations | Number of times a schema in cache became invalid due to changes in data | | SchemaInferenceCacheMisses | Number of times the requested source is not in schema cache | | SchemaInferenceCacheNumRowsHits | Number of times the number of rows is found in schema cache during count from files | | SchemaInferenceCacheNumRowsMisses | Number of times the requested source is in cache but the number of rows is not in cache while count from files | | SchemaInferenceCacheSchemaHits | Number of times the schema is found in schema cache during schema inference | | SchemaInferenceCacheSchemaMisses | Number of times the requested source is in cache but the schema is not in cache during schema inference | | Seek | Number of times the 'lseek' function was called. | | SelectQueriesWithPrimaryKeyUsage | Count SELECT queries which use the primary key to evaluate the WHERE condition | | SelectQueriesWithSubqueries | Count SELECT queries with all subqueries | | SelectQuery | Same as Query, but only for SELECT queries. | | SelectQueryTimeMicroseconds | Total time of SELECT queries. | | SelectedBytes | Number of bytes (uncompressed; for columns as they stored in memory) SELECTed from all tables. | | SelectedMarks | Number of marks (index granules) selected to read from a MergeTree table. | | SelectedMarksTotal | Number of total marks (index granules) before selecting which ones to read from a MergeTree table. | | SelectedParts | Number of data parts selected to read from a MergeTree table. | | SelectedPartsTotal | Number of total data parts before selecting which ones to read from a MergeTree table. | | SelectedRanges | Number of (non-adjacent) ranges in all data parts selected to read from a MergeTree table. | | SelectedRows | Number of rows SELECTed from all tables. | | SelfDuplicatedAsyncInserts | Number of async inserts in the INSERTed block to a ReplicatedMergeTree table was self deduplicated. | | ServerStartupMilliseconds | Time elapsed from starting server to listening to sockets in milliseconds | | SharedDatabaseCatalogFailedToApplyState | Number of failures to apply new state in SharedDatabaseCatalog | | SharedDatabaseCatalogStateApplicationMicroseconds | Total time spend on application of new state in SharedDatabaseCatalog | | SharedMergeTreeCondemnedPartsKillRequest | How many ZooKeeper requests were used to remove condemned parts | | SharedMergeTreeCondemnedPartsLockConflict | How many times we failed to acquite lock because of conflict | | SharedMergeTreeCondemnedPartsRemoved | How many condemned parts were removed | | SharedMergeTreeDataPartsFetchAttempt | How many times we tried to fetch data parts | | SharedMergeTreeDataPartsFetchFromPeer | How many times we fetch data parts from peer | | SharedMergeTreeDataPartsFetchFromPeerMicroseconds | Data parts fetch from peer microseconds | | SharedMergeTreeDataPartsFetchFromS3 | How many times we fetch data parts from S3 | | SharedMergeTreeHandleBlockingParts | How many blocking parts to handle in scheduleDataProcessingJob | | SharedMergeTreeHandleBlockingPartsMicroseconds | Time of handling blocking parts in scheduleDataProcessingJob | | SharedMergeTreeHandleFetchPartsMicroseconds | Time of handling fetched parts in scheduleDataProcessingJob | | SharedMergeTreeHandleOutdatedParts | How many outdated parts to handle in scheduleDataProcessingJob | | SharedMergeTreeHandleOutdatedPartsMicroseconds | Time of handling outdated parts in scheduleDataProcessingJob | | SharedMergeTreeLoadChecksumAndIndexesMicroseconds | Time of loadColumnsChecksumsIndexes only for SharedMergeTree | | SharedMergeTreeMergeMutationAssignmentAttempt | How many times we tried to assign merge or mutation | | SharedMergeTreeMergeMutationAssignmentFailedWithConflict | How many times we tried to assign merge or mutation and failed because of conflict in Keeper | | SharedMergeTreeMergeMutationAssignmentFailedWithNothingToDo | How many times we tried to assign merge or mutation and failed because nothing to merge | | SharedMergeTreeMergeMutationAssignmentSuccessful | How many times we tried to assign merge or mutation | | SharedMergeTreeMergePartsMovedToCondemned | How many parts moved to condemned directory | | SharedMergeTreeMergePartsMovedToOudated | How many parts moved to oudated directory | | SharedMergeTreeMergeSelectingTaskMicroseconds | Merge selecting task microseconds for SMT | | SharedMergeTreeMetadataCacheHintLoadedFromCache | Number of times metadata cache hint was found without going to Keeper | | SharedMergeTreeOptimizeAsync | Asynchronous OPTIMIZE queries executed | | SharedMergeTreeOptimizeSync | Synchronous OPTIMIZE queries executed | | SharedMergeTreeOutdatedPartsConfirmationInvocations | How many invocations were made to confirm outdated parts | | SharedMergeTreeOutdatedPartsConfirmationRequest | How many ZooKeeper requests were used to config outdated parts | | SharedMergeTreeOutdatedPartsHTTPRequest | How many HTTP requests were send to confirm outdated parts | | SharedMergeTreeOutdatedPartsHTTPResponse | How many HTTP responses were send to confirm outdated parts | | SharedMergeTreePartsKillerMicroseconds | How much time does parts killer main thread takes | | SharedMergeTreePartsKillerParts | How many parts has been scheduled by the killer | | SharedMergeTreePartsKillerPartsMicroseconds | How many time does it take to remove parts (executed from multiple threads) | | SharedMergeTreePartsKillerRuns | How many times parts killer has been running | | SharedMergeTreeReplicaSetUpdatesFromZooKeeper | How many times we have update replica set from ZooKeeper | | SharedMergeTreeReplicaSetUpdatesFromZooKeeperMicroseconds | How much time we spend to update replica set | | SharedMergeTreeReplicaSetUpdatesFromZooKeeperRequests | How many total ZooKeeper requests we made to update replica set | | SharedMergeTreeScheduleDataProcessingJob | How many times scheduleDataProcessingJob called/ | | SharedMergeTreeScheduleDataProcessingJobMicroseconds | scheduleDataProcessingJob execute time | | SharedMergeTreeScheduleDataProcessingJobNothingToScheduled | How many times scheduleDataProcessingJob called but nothing to do | | SharedMergeTreeSelectPartsForCoordinatedFetchMicroseconds | Time of selectPartsForCoordinatedFetch | | SharedMergeTreeSelectPartsForCoordinatedFetchParts | Number of parts selected by selectPartsForCoordinatedFetch | | SharedMergeTreeSelectPartsForFullFetchMicroseconds | Time of selectPartsForFullFetch | | SharedMergeTreeSelectPartsForFullFetchParts | Number of parts selected by selectPartsForFullFetch | | SharedMergeTreeSelectPartsForRendezvousFetchMicroseconds | Time of selectPartsForRendezvousFetch | | SharedMergeTreeSelectPartsForRendezvousFetchParts | Number of parts selected by selectPartsForRendezvousFetch | | SharedMergeTreeSnapshotPartsCleanRequest | How many times SnapshotCleanerThread decides to clean a part | | SharedMergeTreeSnapshotPartsCleanerMicroseconds | How long time SnapshotCleanerThread has run | | SharedMergeTreeSnapshotPartsCleanerParts | How long time SnapshotCleanerThread tries to clean a part | | SharedMergeTreeSnapshotPartsCleanerPartsMicroseconds | How long time SnapshotCleanerThread takes to clean parts | | SharedMergeTreeSnapshotPartsCleanerRuns | How many times SnapshotCleanerThread runs | | SharedMergeTreeSnapshotPartsRemoved | How many times SnapshotCleanerThread successfully clean a part | | SharedMergeTreeTryUpdateDiskMetadataCacheForPartMicroseconds | Time of tryUpdateDiskMetadataCacheForPart in scheduleDataProcessingJob | | SharedMergeTreeVirtualPartsUpdateMicroseconds | Virtual parts update microseconds | | SharedMergeTreeVirtualPartsUpdates | Virtual parts update count | | SharedMergeTreeVirtualPartsUpdatesByLeader | Virtual parts updates by leader | | SharedMergeTreeVirtualPartsUpdatesForMergesOrStatus | Virtual parts updates from non-default background job | | SharedMergeTreeVirtualPartsUpdatesFromPeer | Virtual parts updates count from peer | | SharedMergeTreeVirtualPartsUpdatesFromPeerMicroseconds | Virtual parts updates from peer microseconds | | SharedMergeTreeVirtualPartsUpdatesFromZooKeeper | Virtual parts updates count from ZooKeeper | | SharedMergeTreeVirtualPartsUpdatesFromZooKeeperMicroseconds | Virtual parts updates from ZooKeeper microseconds | | SharedMergeTreeVirtualPartsUpdatesLeaderFailedElection | Virtual parts updates leader election failed | | SharedMergeTreeVirtualPartsUpdatesLeaderSuccessfulElection | Virtual parts updates leader election successful | | SharedMergeTreeVirtualPartsUpdatesPeerNotFound | Virtual updates from peer failed because no one found | | SharedPartsLockHoldMicroseconds | Total time spent holding shared data parts lock in MergeTree tables | | SharedPartsLockWaitMicroseconds | Total time spent waiting for shared data parts lock in MergeTree tables | | SharedPartsLocks | Number of times shared data parts lock has been acquired for MergeTree tables | | SleepFunctionCalls | Number of times a sleep function (sleep, sleepEachRow) has been called. | | SleepFunctionElapsedMicroseconds | Time spent sleeping in a sleep function (sleep, sleepEachRow). | | SleepFunctionMicroseconds | Time set to sleep in a sleep function (sleep, sleepEachRow). | | SlowRead | Number of reads from a file that were slow. This indicate system overload. Thresholds are controlled by read_backoff* settings. | | SoftPageFaults | The number of soft page faults in query execution threads. Soft page fault usually means a miss in the memory allocator cache, which requires a new memory mapping from the OS and subsequent allocation of a page of physical memory. | | StorageBufferErrorOnFlush | Number of times a buffer in the 'Buffer' table has not been able to flush due to error writing in the destination table. | | StorageBufferFlush | Number of times a buffer in a 'Buffer' table was flushed. | | StorageBufferLayerLockReadersWaitMilliseconds | Time for waiting for Buffer layer during reading. | | StorageBufferLayerLockWritersWaitMilliseconds | Time for waiting free Buffer layer to write to (can be used to tune Buffer layers). | | StorageBufferPassedAllMinThresholds | Number of times a criteria on min thresholds has been reached to flush a buffer in a 'Buffer' table. | | StorageBufferPassedBytesFlushThreshold | Number of times background-only flush threshold on bytes has been reached to flush a buffer in a 'Buffer' table. This is expert-only metric. If you read this and you are not an expert, stop reading. | | StorageBufferPassedBytesMaxThreshold | Number of times a criteria on max bytes threshold has been reached to flush a buffer in a 'Buffer' table. | | StorageBufferPassedRowsFlushThreshold | Number of times background-only flush threshold on rows has been reached to flush a buffer in a 'Buffer' table. This is expert-only metric. If you read this and you are not an expert, stop reading. | | StorageBufferPassedRowsMaxThreshold | Number of times a criteria on max rows threshold has been reached to flush a buffer in a 'Buffer' table. | | StorageBufferPassedTimeFlushThreshold | Number of times background-only flush threshold on time has been reached to flush a buffer in a 'Buffer' table. This is expert-only metric. If you read this and you are not an expert, stop reading. | | StorageBufferPassedTimeMaxThreshold | Number of times a criteria on max time threshold has been reached to flush a buffer in a 'Buffer' table. | | StorageConnectionsCreated | Number of created connections for storages | | StorageConnectionsElapsedMicroseconds | Total time spend on creating connections for storages | | StorageConnectionsErrors | Number of cases when creation of a connection for storage is failed | | StorageConnectionsExpired | Number of expired connections for storages | | StorageConnectionsPreserved | Number of preserved connections for storages | | StorageConnectionsReset | Number of reset connections for storages | | StorageConnectionsReused | Number of reused connections for storages | | SummingSortedMilliseconds | Total time spent while summing sorted columns | | SuspendSendingQueryToShard | Total count when sending query to shard was suspended when async_query_sending_for_remote is enabled. | | SynchronousReadWaitMicroseconds | Time spent in waiting for synchronous reads in asynchronous local read. | | SynchronousRemoteReadWaitMicroseconds | Time spent in waiting for synchronous remote reads. | | SystemLogErrorOnFlush | Number of times any of the system logs have failed to flush to the corresponding system table. Attempts to flush are repeated. | | SystemTimeMicroseconds | Total time spent in processing (queries and other tasks) threads executing CPU instructions in OS kernel mode. This is time spent in syscalls, excluding waiting time during blocking syscalls. | | TableFunctionExecute | Number of table function calls. | | TextIndexDiscardHint | Number of index granules where a direct reading from the text index was added as hint and was discarded due to low selectivity. | | TextIndexHeaderCacheHits | Number of times a header has been found in the cache. | | TextIndexHeaderCacheMisses | Number of times a header has not been found in the cache. | | TextIndexPostingsCacheHits | Number of times a text index posting list has been found in the cache. | | TextIndexPostingsCacheMisses | Number of times a a text index posting list has not been found in the cache. | | TextIndexReadDictionaryBlocks | Number of times a text index dictionary block has been read from disk. | | TextIndexReadGranulesMicroseconds | Total time spent reading and analyzing granules of the text index. | | TextIndexReadPostings | Number of times a posting list has been read from the text index. | | TextIndexReadSparseIndexBlocks | Number of times a sparse index block has been read from the text index. | | TextIndexReaderTotalMicroseconds | Total time spent reading the text index. | | TextIndexTokensCacheHits | Number of times a text index token info has been found in the cache. | | TextIndexTokensCacheMisses | Number of times a text index token info has not been found in the cache. | | TextIndexUseHint | Number of index granules where a direct reading from the text index was added as hint and was used. | | TextIndexUsedEmbeddedPostings | Number of times a posting list embedded in the dictionary has been used. | | ThreadPoolReaderPageCacheHit | Number of times the read inside ThreadPoolReader was done from the page cache. | | ThreadPoolReaderPageCacheHitBytes | Number of bytes read inside ThreadPoolReader when it was done from the page cache. | | ThreadPoolReaderPageCacheHitElapsedMicroseconds | Time spent reading data from page cache in ThreadPoolReader. | | ThreadPoolReaderPageCacheMiss | Number of times the read inside ThreadPoolReader was not done from page cache and was hand off to thread pool. | | ThreadPoolReaderPageCacheMissBytes | Number of bytes read inside ThreadPoolReader when read was not done from page cache and was hand off to thread pool. | | ThreadPoolReaderPageCacheMissElapsedMicroseconds | Time spent reading data inside the asynchronous job in ThreadPoolReader - when read was not done from the page cache. | | ThreadpoolReaderPrepareMicroseconds | Time spent on preparation (e.g. call to reader seek() method) | | ThreadpoolReaderReadBytes | Bytes read from a threadpool task in asynchronous reading | | ThreadpoolReaderSubmit | Bytes read from a threadpool task in asynchronous reading | | ThreadpoolReaderSubmitLookupInCacheMicroseconds | How much time we spent checking if content is cached | | ThreadpoolReaderSubmitReadSynchronously | How many times we haven't scheduled a task on the thread pool and read synchronously instead | | ThreadpoolReaderSubmitReadSynchronouslyBytes | How many bytes were read synchronously | | ThreadpoolReaderSubmitReadSynchronouslyMicroseconds | How much time we spent reading synchronously | | ThreadpoolReaderTaskMicroseconds | Time spent getting the data in asynchronous reading | | ThrottlerSleepMicroseconds | Total time a query was sleeping to conform all throttling settings. | | TinyS3Clients | Number of S3 clients copies which reuse an existing auth provider from another client. | | USearchAddComputedDistances | Number of times distance was computed when adding vectors to usearch indexes. | | USearchAddCount | Number of vectors added to usearch indexes. | | USearchAddVisitedMembers | Number of nodes visited when adding vectors to usearch indexes. | | USearchSearchComputedDistances | Number of times distance was computed when searching usearch indexes. | | USearchSearchCount | Number of search operations performed in usearch indexes. | | USearchSearchVisitedMembers | Number of nodes visited when searching in usearch indexes. | | UncompressedCacheHits | Number of times a block of data has been found in the uncompressed cache (and decompression was avoided). | | UncompressedCacheMisses | Number of times a block of data has not been found in the uncompressed cache (and required decompression). | | UncompressedCacheWeightLost | Number of bytes evicted from the uncompressed cache. | | UserTimeMicroseconds | Total time spent in processing (queries and other tasks) threads executing CPU instructions in user mode. This includes time CPU pipeline was stalled due to main memory access, cache misses, branch mispredictions, hyper-threading, etc. | | VectorSimilarityIndexCacheHits | Number of times an index granule has been found in the vector index cache. | | VectorSimilarityIndexCacheMisses | Number of times an index granule has not been found in the vector index cache and had to be read from disk. | | VectorSimilarityIndexCacheWeightLost | Approximate number of bytes evicted from the vector index cache. | | VersionedCollapsingSortedMilliseconds | Total time spent while version collapsing sorted columns | | WaitMarksLoadMicroseconds | Time spent loading marks | | WaitPrefetchTaskMicroseconds | Time spend waiting for prefetched reader | | WasmDeserializationMicroseconds | Time spent executing WebAssembly code | | WasmGuestExecuteMicroseconds | Time spent executing WebAssembly code | | WasmMemoryAllocated | Total memory allocated for WebAssembly compartments | | WasmModuleInstatiate | Number of WebAssembly compartments created | | WasmSerializationMicroseconds | Time spent executing WebAssembly code | | WasmTotalExecuteMicroseconds | Time spent executing WebAssembly code | | WriteBufferFromFileDescriptorWrite | Number of writes (write/pwrite) to a file descriptor. Does not include sockets. | | WriteBufferFromFileDescriptorWriteBytes | Number of bytes written to file descriptors. If the file is compressed, this will show compressed data size. | | WriteBufferFromFileDescriptorWriteFailed | Number of times the write (write/pwrite) to a file descriptor have failed. | | WriteBufferFromHTTPBytes | Total size of payload bytes received and sent by WriteBufferFromHTTP. Doesn't include HTTP headers. | | WriteBufferFromHTTPRequestsSent | Number of HTTP requests sent by WriteBufferFromHTTP | | WriteBufferFromS3Bytes | Bytes written to S3. | | WriteBufferFromS3Microseconds | Time spent on writing to S3. | | WriteBufferFromS3RequestsErrors | Number of exceptions while writing to S3. | | WriteBufferFromS3WaitInflightLimitMicroseconds | Time spent on waiting while some of the current requests are done when its number reached the limit defined by s3_max_inflight_parts_for_one_file. | | ZooKeeperBytesReceived | Number of bytes received over network while communicating with ZooKeeper. | | ZooKeeperBytesSent | Number of bytes send over network while communicating with ZooKeeper. | | ZooKeeperCheck | Number of 'check' requests to ZooKeeper. Usually they don't make sense in isolation, only as part of a complex transaction. | | ZooKeeperClose | Number of times connection with ZooKeeper has been closed voluntary. | | ZooKeeperCreate | Number of 'create' requests to ZooKeeper. | | ZooKeeperExists | Number of 'exists' requests to ZooKeeper. | | ZooKeeperGet | Number of 'get' requests to ZooKeeper. | | ZooKeeperGetACL | Number of 'getACL' requests to ZooKeeper. | | ZooKeeperHardwareExceptions | Number of exceptions while working with ZooKeeper related to network (connection loss or similar). | | ZooKeeperInit | Number of times connection with ZooKeeper has been established. | | ZooKeeperList | Number of 'list' (getChildren) requests to ZooKeeper. | | ZooKeeperMulti | Number of 'multi' requests to ZooKeeper (compound transactions). | | ZooKeeperMultiRead | Number of read 'multi' requests to ZooKeeper (compound transactions). | | ZooKeeperMultiWrite | Number of write 'multi' requests to ZooKeeper (compound transactions). | | ZooKeeperOtherExceptions | Number of exceptions while working with ZooKeeper other than ZooKeeperUserExceptions and ZooKeeperHardwareExceptions. | | ZooKeeperReconfig | Number of 'reconfig' requests to ZooKeeper. | | ZooKeeperRemove | Number of 'remove' requests to ZooKeeper. | | ZooKeeperSet | Number of 'set' requests to ZooKeeper. | | ZooKeeperSync | Number of 'sync' requests to ZooKeeper. These requests are rarely needed or usable. | | ZooKeeperTransactions | Number of ZooKeeper operations, which include both read and write operations as well as multi-transactions. | | ZooKeeperUserExceptions | Number of exceptions while working with ZooKeeper related to the data (no node, bad version or similar). | | ZooKeeperWaitMicroseconds | Number of microseconds spent waiting for responses from ZooKeeper after creating a request, summed across all the requesting threads. | | ZooKeeperWatchResponse | Number of times watch notification has been received from ZooKeeper. |

See Also

• system.asynchronous_metrics — Contains periodically calculated metrics.
• system.metrics — Contains instantly calculated metrics.
• system.metric_log — Contains a history of metrics values from tables system.metrics and system.events.
• Monitoring — Base concepts of ClickHouse monitoring.