system.metrics

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 metrics which can be calculated instantly, or have a current value. For example, the number of simultaneously processed queries or the current replica delay. This table is always up to date.

Columns:

metric (String) — Metric name.
value (Int64) — Metric value.
description (String) — Metric description.

You can find all supported metrics in source file src/Common/CurrentMetrics.cpp.

Example

SELECT * FROM system.metrics LIMIT 10

┌─metric───────────────────────────────┬─value─┬─description────────────────────────────────────────────────────────────┐
│ Query                                │     1 │ Number of executing queries                                            │
│ Merge                                │     0 │ Number of executing background merges                                  │
│ PartMutation                         │     0 │ Number of mutations (ALTER DELETE/UPDATE)                              │
│ ReplicatedFetch                      │     0 │ Number of data parts being fetched from replicas                       │
│ ReplicatedSend                       │     0 │ Number of data parts being sent to replicas                            │
│ ReplicatedChecks                     │     0 │ Number of data parts checking for consistency                          │
│ BackgroundMergesAndMutationsPoolTask │     0 │ Number of active merges and mutations in an associated background pool │
│ BackgroundFetchesPoolTask            │     0 │ Number of active fetches in an associated background pool              │
│ BackgroundCommonPoolTask             │     0 │ Number of active tasks in an associated background pool                │
│ BackgroundMovePoolTask               │     0 │ Number of active tasks in BackgroundProcessingPool for moves           │
└──────────────────────────────────────┴───────┴────────────────────────────────────────────────────────────────────────┘

Metric descriptions

Metric	Description
ASTFuzzerAccumulatedFragments	Number of AST fragments accumulated by the server-side AST fuzzer for use in future mutations.
ActiveTimersInQueryProfiler	Number of Active thread local timers in QueryProfiler
AddressesActive	Total count of addresses which are used for creation connections with connection pools
AddressesBanned	Total count of addresses which are banned as faulty for creation connections with connection pools
AggregatorThreads	Number of threads in the Aggregator thread pool.
AggregatorThreadsActive	Number of threads in the Aggregator thread pool running a task.
AggregatorThreadsScheduled	Number of queued or active jobs in the Aggregator thread pool.
AsyncInsertCacheSize	Number of async insert hash id in cache
AsynchronousInsertQueueBytes	Number of pending bytes in the AsynchronousInsert queue.
AsynchronousInsertQueueSize	Number of pending tasks in the AsynchronousInsert queue.
AsynchronousInsertThreads	Number of threads in the AsynchronousInsert thread pool.
AsynchronousInsertThreadsActive	Number of threads in the AsynchronousInsert thread pool running a task.
AsynchronousInsertThreadsScheduled	Number of queued or active jobs in the AsynchronousInsert thread pool.
AsynchronousReadWait	Number of threads waiting for asynchronous read.
AttachedDatabase	Active databases.
AttachedDictionary	Active dictionaries.
AttachedReplicatedTable	Active replicated tables.
AttachedTable	Active tables.
AttachedView	Active views.
AvroSchemaCacheBytes	Size of the Avro schema cache in bytes
AvroSchemaCacheCells	Number of cached Avro schemas
AvroSchemaRegistryCacheBytes	Size of the Avro schema registry cache in bytes
AvroSchemaRegistryCacheCells	Number of entries in Avro schema registry cache
AzureRequests	Number of currently executing Azure requests
BackgroundBufferFlushSchedulePoolSize	Limit on number of tasks in BackgroundBufferFlushSchedulePool
BackgroundBufferFlushSchedulePoolTask	Number of active tasks in BackgroundBufferFlushSchedulePool. This pool is used for periodic Buffer flushes
BackgroundCommonPoolSize	Limit on number of tasks in an associated background pool
BackgroundCommonPoolTask	Number of active tasks in an associated background pool
BackgroundDistributedSchedulePoolSize	Limit on number of tasks in BackgroundDistributedSchedulePool
BackgroundDistributedSchedulePoolTask	Number of active tasks in BackgroundDistributedSchedulePool. This pool is used for distributed sends that is done in background.
BackgroundFetchesPoolSize	Limit on number of simultaneous fetches in an associated background pool
BackgroundFetchesPoolTask	Number of active fetches in an associated background pool
BackgroundMergesAndMutationsPoolSize	Limit on number of active merges and mutations in an associated background pool
BackgroundMergesAndMutationsPoolTask	Number of active merges and mutations in an associated background pool
BackgroundMessageBrokerSchedulePoolSize	Limit on number of tasks in BackgroundMessageBrokerSchedulePool for message streaming
BackgroundMessageBrokerSchedulePoolTask	Number of active tasks in BackgroundMessageBrokerSchedulePool for message streaming
BackgroundMovePoolSize	Limit on number of tasks in BackgroundProcessingPool for moves
BackgroundMovePoolTask	Number of active tasks in BackgroundProcessingPool for moves
BackgroundSchedulePoolSize	Limit on number of tasks in BackgroundSchedulePool. This pool is used for periodic ReplicatedMergeTree tasks, like cleaning old data parts, altering data parts, replica re-initialization, etc.
BackgroundSchedulePoolTask	Number of active tasks in BackgroundSchedulePool. This pool is used for periodic ReplicatedMergeTree tasks, like cleaning old data parts, altering data parts, replica re-initialization, etc.
BackupsIOThreads	Number of threads in the BackupsIO thread pool.
BackupsIOThreadsActive	Number of threads in the BackupsIO thread pool running a task.
BackupsIOThreadsScheduled	Number of queued or active jobs in the BackupsIO thread pool.
BackupsThreads	Number of threads in the thread pool for BACKUP.
BackupsThreadsActive	Number of threads in thread pool for BACKUP running a task.
BackupsThreadsScheduled	Number of queued or active jobs for BACKUP.
BcryptCacheBytes	Total size of the bcrypt authentication cache in bytes
BcryptCacheSize	Total number of entries in the bcrypt authentication cache
BlobCopierThreads	Number of threads in the thread pool of the object storage disk background replication process
BlobCopierThreadsActive	Number of threads in the thread pool of the object storage disk background replication process running a task
BlobCopierThreadsScheduled	Number of queued or active tasks in the thread pool of the object storage disk background replication process
BlobKillerThreads	Number of threads in the thread pool of the object storage disk background removal process
BlobKillerThreadsActive	Number of threads in the thread pool of the object storage disk background removal process running a task
BlobKillerThreadsScheduled	Number of queued or active tasks in the thread pool of the object storage disk background removal process
BrokenDisks	Number of disks disks that were marked as broken during disk check.
BrokenDistributedBytesToInsert	Number of bytes for asynchronous insertion into Distributed tables that has been marked as broken. Number of bytes for every shard is summed.
BrokenDistributedFilesToInsert	Number of files for asynchronous insertion into Distributed tables that has been marked as broken. Number of files for every shard is summed.
BuildVectorSimilarityIndexThreads	Number of threads in the build vector similarity index thread pool.
BuildVectorSimilarityIndexThreadsActive	Number of threads in the build vector similarity index thread pool running a task.
BuildVectorSimilarityIndexThreadsScheduled	Number of queued or active jobs in the build vector similarity index thread pool.
CacheDetachedFileSegments	Number of existing detached cache file segments
CacheDictionaryThreads	Number of threads in the CacheDictionary thread pool.
CacheDictionaryThreadsActive	Number of threads in the CacheDictionary thread pool running a task.
CacheDictionaryThreadsScheduled	Number of queued or active jobs in the CacheDictionary thread pool.
CacheDictionaryUpdateQueueBatches	Number of 'batches' (a set of keys) in update queue in CacheDictionaries.
CacheDictionaryUpdateQueueKeys	Exact number of keys in update queue in CacheDictionaries.
CacheFileSegments	Number of existing cache file segments
CacheWarmerBytesInProgress	Total size of remote file segments waiting to be asynchronously loaded into filesystem cache.
ColumnsDescriptionsCacheSize	Size of ColumnsDescriptions cache (per-table cache)
CompiledExpressionCacheBytes	Total bytes used for the cache of JIT-compiled code
CompiledExpressionCacheCount	Total entries in the cache of JIT-compiled code
Compressing	Number of compress operations using internal compression codecs
CompressionThread	Number of threads in compression thread pools.
CompressionThreadActive	Number of threads in compression thread pools running a task.
CompressionThreadScheduled	Number of queued or active jobs in compression thread pools.
ConcurrencyControlAcquired	Total number of acquired CPU slots
ConcurrencyControlAcquiredNonCompeting	Total number of acquired CPU slots that are not considered competing (the first thread if fair_round_robin scheduler is in use)
ConcurrencyControlPreempted	Total number of preempted threads waiting for CPU slot
ConcurrencyControlScheduled	Total number of CPU slot requests are being scheduled currently
ConcurrencyControlSoftLimit	Value of soft limit on number of CPU slots
ConcurrentHashJoinPoolThreads	Number of threads in the thread pool for concurrent hash join.
ConcurrentHashJoinPoolThreadsActive	Number of threads in the thread pool for concurrent hash join running a task.
ConcurrentHashJoinPoolThreadsScheduled	Number of queued or active jobs in the thread pool for concurrent hash join.
ConcurrentQueryAcquired	Total number of acquired query slots
ConcurrentQueryScheduled	Total number of query slot requests are being scheduled currently
ContextLockWait	Number of threads waiting for lock in Context. This is global lock.
CoordinatedMergesCoordinatorAssignedMerges	Number of assigned merges in merge coordinator state.
CoordinatedMergesCoordinatorRunningMerges	Number of running merges visible for merge coordinator.
CoordinatedMergesWorkerAssignedMerges	Number of assigned merges in merge worker state.
CreatedTimersInQueryProfiler	Number of Created thread local timers in QueryProfiler
DDLWorkerThreads	Number of threads in the DDLWorker thread pool for ON CLUSTER queries.
DDLWorkerThreadsActive	Number of threads in the DDLWORKER thread pool for ON CLUSTER queries running a task.
DDLWorkerThreadsScheduled	Number of queued or active jobs in the DDLWORKER thread pool for ON CLUSTER queries.
DNSAddressesCacheBytes	Size of the DNS addresses cache in bytes
DNSAddressesCacheSize	Number of cached DNS addresses
DNSHostsCacheBytes	Size of the DNS hosts cache in bytes
DNSHostsCacheSize	Number of cached DNS hosts
DatabaseBackupThreads	Number of threads in the DatabaseBackup thread pool.
DatabaseBackupThreadsActive	Number of threads in the DatabaseBackup thread pool running a task.
DatabaseBackupThreadsScheduled	Number of queued or active jobs in the DatabaseBackup thread pool.
DatabaseCatalogThreads	Number of threads in the DatabaseCatalog thread pool.
DatabaseCatalogThreadsActive	Number of threads in the DatabaseCatalog thread pool running a task.
DatabaseCatalogThreadsScheduled	Number of queued or active jobs in the DatabaseCatalog thread pool.
DatabaseOnDiskThreads	Number of threads in the DatabaseOnDisk thread pool.
DatabaseOnDiskThreadsActive	Number of threads in the DatabaseOnDisk thread pool running a task.
DatabaseOnDiskThreadsScheduled	Number of queued or active jobs in the DatabaseOnDisk thread pool.
DatabaseReplicatedCreateTablesThreads	Number of threads in the threadpool for table creation in DatabaseReplicated.
DatabaseReplicatedCreateTablesThreadsActive	Number of active threads in the threadpool for table creation in DatabaseReplicated.
DatabaseReplicatedCreateTablesThreadsScheduled	Number of queued or active jobs in the threadpool for table creation in DatabaseReplicated.
Decompressing	Number of decompress operations using internal compression codecs
DelayedInserts	Number of INSERT queries that are throttled due to high number of active data parts for partition in a MergeTree table.
DeltaLakeSnapshotCacheSizeElements	Size in elements of DeltaLake snapshot cache.
DestroyAggregatesThreads	Number of threads in the thread pool for destroy aggregate states.
DestroyAggregatesThreadsActive	Number of threads in the thread pool for destroy aggregate states running a task.
DestroyAggregatesThreadsScheduled	Number of queued or active jobs in the thread pool for destroy aggregate states.
DictCacheRequests	Number of requests in fly to data sources of dictionaries of cache type.
DiskConnectionsStored	Total count of sessions stored in the session pool for disks
DiskConnectionsTotal	Total count of all sessions: stored in the pool and actively used right now for disks
DiskObjectStorageAsyncThreads	Obsolete metric, shows nothing.
DiskObjectStorageAsyncThreadsActive	Obsolete metric, shows nothing.
DiskPlainRewritableAzureDirectoryMapSize	Number of local-to-remote path entries in the 'plain_rewritable' in-memory map for AzureObjectStorage.
DiskPlainRewritableAzureFileCount	Number of file entries in the 'plain_rewritable' in-memory map for AzureObjectStorage.
DiskPlainRewritableLocalDirectoryMapSize	Number of local-to-remote path entries in the 'plain_rewritable' in-memory map for LocalObjectStorage.
DiskPlainRewritableLocalFileCount	Number of file entries in the 'plain_rewritable' in-memory map for LocalObjectStorage.
DiskPlainRewritableS3DirectoryMapSize	Number of local-to-remote path entries in the 'plain_rewritable' in-memory map for S3ObjectStorage.
DiskPlainRewritableS3FileCount	Number of file entries in the 'plain_rewritable' in-memory map for S3ObjectStorage.
DiskS3NoSuchKeyErrors	The number of `NoSuchKey` errors that occur when reading data from S3 cloud storage through ClickHouse disks.
DiskSpaceReservedForMerge	Disk space reserved for currently running background merges. It is slightly more than the total size of currently merging parts.
DistrCacheAllocatedConnections	Number of currently allocated connections to Distributed Cache connection pool
DistrCacheBorrowedConnections	Number of currently borrowed connections to Distributed Cache connection pool
DistrCacheOpenedConnections	Number of open connections to Distributed Cache
DistrCacheReadBuffers	Number of distributed cache read buffers
DistrCacheReadRequests	Number of executed Read requests to Distributed Cache
DistrCacheRegisteredServers	Number of distributed cache registered servers
DistrCacheRegisteredServersCurrentAZ	Number of distributed cache registered servers in current az
DistrCacheServerConnections	Number of open connections to ClickHouse server from Distributed Cache
DistrCacheServerRegistryConnections	Number of active connections to ClickHouse server from Distributed Cache (not marked as cancelled because of limit)
DistrCacheServerS3CachedClients	Number of distributed cache S3 cached clients
DistrCacheSharedLimitCount	Number of opened connections according to DistributedCache::ConnectionPool::SharedLimit
DistrCacheUsedConnections	Number of currently used connections to Distributed Cache
DistrCacheWriteBuffers	Number of distributed cache write buffers
DistrCacheWriteRequests	Number of executed Write requests to Distributed Cache
DistributedBytesToInsert	Number of pending bytes to process for asynchronous insertion into Distributed tables. Number of bytes for every shard is summed.
DistributedFilesToInsert	Number of pending files to process for asynchronous insertion into Distributed tables. Number of files for every shard is summed.
DistributedIndexAnalysisThreads	Number of threads in the thread pool for distributed index analysis.
DistributedIndexAnalysisThreadsActive	Number of threads in the thread pool for distributed index analysis running a task.
DistributedIndexAnalysisThreadsScheduled	Number of queued or active jobs in the distributed idnex analysis thread pool.
DistributedInsertThreads	Number of threads used for INSERT into Distributed.
DistributedInsertThreadsActive	Number of threads used for INSERT into Distributed running a task.
DistributedInsertThreadsScheduled	Number of queued or active jobs used for INSERT into Distributed.
DistributedSend	Number of connections to remote servers sending data that was INSERTed into Distributed tables. Both synchronous and asynchronous mode.
DropDistributedCacheThreads	Number of threads in the threadpool for drop distributed cache query.
DropDistributedCacheThreadsActive	Number of active threads in the threadpool for drop distributed cache query.
DropDistributedCacheThreadsScheduled	Number of queued or active jobs in the threadpool for drop distributed cache.
EphemeralNode	Number of ephemeral nodes hold in ZooKeeper.
FilesystemCacheDelayedCleanupElements	Filesystem cache elements in background cleanup queue
FilesystemCacheDownloadQueueElements	Filesystem cache elements in download queue
FilesystemCacheElements	Filesystem cache elements (file segments)
FilesystemCacheHoldFileSegments	Filesystem cache file segment which are currently hold as unreleasable
FilesystemCacheKeys	Number of keys in filesystem cache
FilesystemCacheReadBuffers	Number of active cache buffers
FilesystemCacheReserveThreads	Threads number trying to reserve space in cache
FilesystemCacheSize	Filesystem cache size in bytes
FilesystemCacheSizeLimit	Filesystem cache size limit in bytes
FilteringMarksWithPrimaryKey	Number of threads currently doing filtering of mark ranges by the primary key
FilteringMarksWithSecondaryKeys	Number of threads currently doing filtering of mark ranges by secondary keys
FormatParsingThreads	Number of threads in the thread pool used for parsing input.
FormatParsingThreadsActive	Number of threads in the thread pool used for parsing input running a task.
FormatParsingThreadsScheduled	Number of queued or active jobs in the thread pool used for parsing input.
FreezePartThreads	Number of threads in the threadpool for freezing data parts.
FreezePartThreadsActive	Number of active threads in the threadpool for freezing data parts.
FreezePartThreadsScheduled	Number of queued or active jobs in the threadpool for freezing data parts.
GlobalThread	Number of threads in global thread pool.
GlobalThreadActive	Number of threads in global thread pool running a task.
GlobalThreadScheduled	Number of queued or active jobs in global thread pool.
HTTPConnection	Number of connections to HTTP server
HTTPConnectionsStored	Total count of sessions stored in the session pool for http hosts
HTTPConnectionsTotal	Total count of all sessions: stored in the pool and actively used right now for http hosts
HashedDictionaryThreads	Number of threads in the HashedDictionary thread pool.
HashedDictionaryThreadsActive	Number of threads in the HashedDictionary thread pool running a task.
HashedDictionaryThreadsScheduled	Number of queued or active jobs in the HashedDictionary thread pool.
HiveFilesCacheBytes	Size of the hive cache in bytes
HiveFilesCacheFiles	Number of cached files in the hive cache
HiveMetadataFilesCacheBytes	Size of the hive metadata cache in bytes
HiveMetadataFilesCacheFiles	Number of cached files in the hive metadata cache
IDiskCopierThreads	Number of threads for copying data between disks of different types.
IDiskCopierThreadsActive	Number of threads for copying data between disks of different types running a task.
IDiskCopierThreadsScheduled	Number of queued or active jobs for copying data between disks of different types.
IOPrefetchThreads	Number of threads in the IO prefetch thread pool.
IOPrefetchThreadsActive	Number of threads in the IO prefetch thread pool running a task.
IOPrefetchThreadsScheduled	Number of queued or active jobs in the IO prefetch thread pool.
IOThreads	Number of threads in the IO thread pool.
IOThreadsActive	Number of threads in the IO thread pool running a task.
IOThreadsScheduled	Number of queued or active jobs in the IO thread pool.
IOUringInFlightEvents	Number of io_uring SQEs in flight
IOUringPendingEvents	Number of io_uring SQEs waiting to be submitted
IOWriterThreads	Number of threads in the IO writer thread pool.
IOWriterThreadsActive	Number of threads in the IO writer thread pool running a task.
IOWriterThreadsScheduled	Number of queued or active jobs in the IO writer thread pool.
IcebergCatalogThreads	Number of threads in the IcebergCatalog thread pool.
IcebergCatalogThreadsActive	Number of threads in the IcebergCatalog thread pool running a task.
IcebergCatalogThreadsScheduled	Number of queued or active jobs in the IcebergCatalog thread pool.
IcebergMetadataFilesCacheBytes	Size of the Iceberg metadata cache in bytes
IcebergMetadataFilesCacheFiles	Number of cached files in the Iceberg metadata cache
IndexMarkCacheBytes	Total size of mark cache for secondary indices in bytes
IndexMarkCacheFiles	Total number of mark files cached in the mark cache for secondary indices
IndexUncompressedCacheBytes	Total size of uncompressed cache in bytes for secondary indices. Uncompressed cache does not usually improve the performance and should be mostly avoided
IndexUncompressedCacheCells	Total number of entries in the uncompressed cache for secondary indices. Each entry represents a decompressed block of data. Uncompressed cache does not usually improve performance and should be mostly avoided
InterserverConnection	Number of connections from other replicas to fetch parts
IsServerShuttingDown	Indicates if the server is shutting down: 0 = no, 1 = yes
KafkaAssignedPartitions	Number of partitions Kafka tables currently assigned to
KafkaBackgroundReads	Number of background reads currently working (populating materialized views from Kafka)
KafkaConsumers	Number of active Kafka consumers
KafkaConsumersInUse	Number of consumers which are currently used by direct or background reads
KafkaConsumersWithAssignment	Number of active Kafka consumers which have some partitions assigned.
KafkaLibrdkafkaThreads	Number of active librdkafka threads
KafkaProducers	Number of active Kafka producer created
KafkaWrites	Number of currently running inserts to Kafka
KeeperAliveConnections	Number of alive connections
KeeperOutstandingRequests	Number of outstanding requests
LicenseRemainingSeconds	Remaining seconds of the license validity period.
LocalThread	Obsolete. Number of threads in local thread pools. The threads in local thread pools are taken from the global thread pool.
LocalThreadActive	Obsolete. Number of threads in local thread pools running a task.
LocalThreadScheduled	Obsolete. Number of queued or active jobs in local thread pools.
MMapCacheCells	The number of files opened with `mmap` (mapped in memory). This is used for queries with the setting `local_filesystem_read_method` set to `mmap`. The files opened with `mmap` are kept in the cache to avoid costly TLB flushes.
MMappedFileBytes	Sum size of mmapped file regions.
MMappedFiles	Total number of mmapped files.
MarkCacheBytes	Total size of mark cache in bytes
MarkCacheFiles	Total number of mark files cached in the mark cache
MarksLoaderThreads	Number of threads in thread pool for loading marks.
MarksLoaderThreadsActive	Number of threads in the thread pool for loading marks running a task.
MarksLoaderThreadsScheduled	Number of queued or active jobs in the thread pool for loading marks.
MaxAllocatedEphemeralLockSequentialNumber	The maximum sequential number allocated for ephemeral lock znodes in ZooKeeper. Primarily influenced by the block numbers.
MaxDDLEntryID	Max processed DDL entry of DDLWorker.
MaxPushedDDLEntryID	Max DDL entry of DDLWorker that pushed to zookeeper.
MemoryTracking	Total amount of memory (bytes) allocated by the server.
MemoryTrackingUncorrected	Total amount of memory (bytes) allocated by the server not corrected by RSS.
Merge	Number of executing background merges
MergeJoinBlocksCacheBytes	Total bytes used for cached blocks in MergeJoin
MergeJoinBlocksCacheCount	Total cached blocks in MergeJoin
MergeParts	Number of source parts participating in current background merges
MergeTreeAllRangesAnnouncementsSent	The current number of announcement being sent in flight from the remote server to the initiator server about the set of data parts (for MergeTree tables). Measured on the remote server side.
MergeTreeBackgroundExecutorThreads	Number of threads in the MergeTreeBackgroundExecutor thread pool.
MergeTreeBackgroundExecutorThreadsActive	Number of threads in the MergeTreeBackgroundExecutor thread pool running a task.
MergeTreeBackgroundExecutorThreadsScheduled	Number of queued or active jobs in the MergeTreeBackgroundExecutor thread pool.
MergeTreeDataSelectExecutorThreads	Number of threads in the MergeTreeDataSelectExecutor thread pool.
MergeTreeDataSelectExecutorThreadsActive	Number of threads in the MergeTreeDataSelectExecutor thread pool running a task.
MergeTreeDataSelectExecutorThreadsScheduled	Number of queued or active jobs in the MergeTreeDataSelectExecutor thread pool.
MergeTreeFetchPartitionThreads	Number of threads for ALTER TABLE FETCH PARTITION
MergeTreeFetchPartitionThreadsActive	Number of threads for ALTER TABLE FETCH PARTITION fetching part
MergeTreeFetchPartitionThreadsScheduled	Number of queued or active part fetches in ALTER TABLE FETCH PARTITION
MergeTreeOutdatedPartsLoaderThreads	Number of threads in the threadpool for loading Outdated data parts.
MergeTreeOutdatedPartsLoaderThreadsActive	Number of active threads in the threadpool for loading Outdated data parts.
MergeTreeOutdatedPartsLoaderThreadsScheduled	Number of queued or active jobs in the threadpool for loading Outdated data parts.
MergeTreePartsCleanerThreads	Number of threads in the MergeTree parts cleaner thread pool.
MergeTreePartsCleanerThreadsActive	Number of threads in the MergeTree parts cleaner thread pool running a task.
MergeTreePartsCleanerThreadsScheduled	Number of queued or active jobs in the MergeTree parts cleaner thread pool.
MergeTreePartsLoaderThreads	Number of threads in the MergeTree parts loader thread pool.
MergeTreePartsLoaderThreadsActive	Number of threads in the MergeTree parts loader thread pool running a task.
MergeTreePartsLoaderThreadsScheduled	Number of queued or active jobs in the MergeTree parts loader thread pool.
MergeTreeReadTaskRequestsSent	The current number of callback requests in flight from the remote server back to the initiator server to choose the read task (for MergeTree tables). Measured on the remote server side.
MergeTreeSnapshotCommitThreads	Number of threads used to commit snapshot
MergeTreeSnapshotCommitThreadsActive	Number of active threads used to commit snapshot
MergeTreeSnapshotCommitThreadsScheduled	Number of scheduled threads used to commit snapshot
MergeTreeSubcolumnsReaderThreads	Number of threads in the thread pool used for subcolumns reading in MergeTree.
MergeTreeSubcolumnsReaderThreadsActive	Number of threads in the thread pool used for subcolumns reading in MergeTree running a task.
MergeTreeSubcolumnsReaderThreadsScheduled	Number of queued or active jobs in the thread pool used for subcolumns reading in MergeTree.
MergeTreeUnexpectedPartsLoaderThreads	Number of threads in the threadpool for loading Unexpected data parts.
MergeTreeUnexpectedPartsLoaderThreadsActive	Number of active threads in the threadpool for loading Unexpected data parts.
MergeTreeUnexpectedPartsLoaderThreadsScheduled	Number of queued or active jobs in the threadpool for loading Unexpected data parts.
MergesMutationsMemoryTracking	Total amount of memory (bytes) allocated by background tasks (merges and mutations).
MetadataFromKeeperCacheObjects	Number of objects in disk metadata cache.
Move	Number of currently executing moves
MySQLConnection	Number of client connections using MySQL protocol
NamedCollection	Number of named collections
NetworkReceive	Number of threads receiving data from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
NetworkSend	Number of threads sending data to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.
ObjectStorageAzureThreads	Number of threads in the AzureObjectStorage thread pool.
ObjectStorageAzureThreadsActive	Number of threads in the AzureObjectStorage thread pool running a task.
ObjectStorageAzureThreadsScheduled	Number of queued or active jobs in the AzureObjectStorage thread pool.
ObjectStorageQueueMetadataCacheSizeBytes	Size in bytes of ObjectStorageQueue metadata cache.
ObjectStorageQueueMetadataCacheSizeElements	Size in elements of ObjectStorageQueue metadata cache.
ObjectStorageQueueRegisteredServers	Number of registered servers in StorageS3(Azure)Queue
ObjectStorageQueueShutdownThreads	Number of threads in object storage queue shutdown pool.
ObjectStorageQueueShutdownThreadsActive	Number of threads in object storage queue shutdown pool running a task.
ObjectStorageQueueShutdownThreadsScheduled	Number of queued or active jobs in object storage queue shutdown pool.
ObjectStorageS3Threads	Number of threads in the S3ObjectStorage thread pool.
ObjectStorageS3ThreadsActive	Number of threads in the S3ObjectStorage thread pool running a task.
ObjectStorageS3ThreadsScheduled	Number of queued or active jobs in the S3ObjectStorage thread pool.
OpenFileForRead	Number of files open for reading
OpenFileForWrite	Number of files open for writing
OutdatedPartsLoadingThreads	Number of threads in the threadpool for loading Outdated data parts.
OutdatedPartsLoadingThreadsActive	Number of active threads in the threadpool for loading Outdated data parts.
OutdatedPartsLoadingThreadsScheduled	Number of queued or active jobs in the threadpool for loading Outdated data parts.
PageCacheBytes	Total size of userspace page cache in bytes
PageCacheCells	Total number of entries in the userspace page cache
ParallelCompressedWriteBufferThreads	Number of threads in all instances of ParallelCompressedWriteBuffer - these threads are doing parallel compression and writing
ParallelCompressedWriteBufferWait	Number of threads in all instances of ParallelCompressedWriteBuffer that are currently waiting for buffer to become available for writing
ParallelFormattingOutputFormatThreads	Number of threads in the ParallelFormattingOutputFormatThreads thread pool.
ParallelFormattingOutputFormatThreadsActive	Number of threads in the ParallelFormattingOutputFormatThreads thread pool running a task.
ParallelFormattingOutputFormatThreadsScheduled	Number of queued or active jobs in the ParallelFormattingOutputFormatThreads thread pool.
ParallelWithQueryActiveThreads	Number of active threads in the threadpool for processing PARALLEL WITH queries.
ParallelWithQueryScheduledThreads	Number of queued or active jobs in the threadpool for processing PARALLEL WITH queries.
ParallelWithQueryThreads	Number of threads in the threadpool for processing PARALLEL WITH queries.
ParquetEncoderThreads	Number of threads in ParquetBlockOutputFormat thread pool.
ParquetEncoderThreadsActive	Number of threads in ParquetBlockOutputFormat thread pool running a task.
ParquetEncoderThreadsScheduled	Number of queued or active jobs in ParquetBlockOutputFormat thread pool.
ParquetMetadataCacheBytes	Size of the Parquet metadata cache in bytes
ParquetMetadataCacheFiles	Number of cached files in the Parquet metadata cache
PartMutation	Number of mutations (ALTER DELETE/UPDATE)
PartsActive	Active data part, used by current and upcoming SELECTs.
PartsCommitted	Deprecated. See PartsActive.
PartsCompact	Compact parts.
PartsDeleteOnDestroy	Part was moved to another disk and should be deleted in own destructor.
PartsDeleting	Not active data part with identity refcounter, it is deleting right now by a cleaner.
PartsOutdated	Not active data part, but could be used by only current SELECTs, could be deleted after SELECTs finishes.
PartsPreActive	The part is in data_parts, but not used for SELECTs.
PartsPreCommitted	Deprecated. See PartsPreActive.
PartsTemporary	The part is generating now, it is not in data_parts list.
PartsWide	Wide parts.
PendingAsyncInsert	Number of asynchronous inserts that are waiting for flush.
PolygonDictionaryThreads	Number of threads in the threadpool for polygon dictionaries.
PolygonDictionaryThreadsActive	Number of active threads in the threadpool for polygon dictionaries.
PolygonDictionaryThreadsScheduled	Number of queued or active jobs in the threadpool for polygon dictionaries.
PostgreSQLConnection	Number of client connections using PostgreSQL protocol
PrimaryIndexCacheBytes	Total size of primary index cache in bytes
PrimaryIndexCacheFiles	Total number of index files cached in the primary index cache
Query	Number of executing queries
QueryCacheBytes	Total size of the query cache in bytes
QueryCacheEntries	Total number of entries in the query cache
QueryConditionCacheBytes	Total size of the query condition cache in bytes
QueryConditionCacheEntries	Total number of entries in the query condition cache
QueryNonInternal	Number of executing non-internal queries (queries initiated by users, excluding internal queries from ClickHouse)
QueryPipelineExecutorThreads	Number of threads in the PipelineExecutor thread pool.
QueryPipelineExecutorThreadsActive	Number of threads in the PipelineExecutor thread pool running a task.
QueryPipelineExecutorThreadsScheduled	Number of queued or active jobs in the PipelineExecutor thread pool.
QueryPreempted	Number of running tasks which are paused and waiting due to 'priority' setting.
QueryThread	Number of query processing threads
RWLockActiveReaders	Number of threads holding read lock in a table RWLock.
RWLockActiveWriters	Number of threads holding write lock in a table RWLock.
RWLockWaitingReaders	Number of threads waiting for read on a table RWLock.
RWLockWaitingWriters	Number of threads waiting for write on a table RWLock.
Read	Number of read (read, pread, io_getevents, etc.) syscalls in fly
ReadTaskRequestsSent	The current number of callback requests in flight 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.
ReadonlyDisks	Number of disks that were marked as readonly during disk check.
ReadonlyReplica	Number of Replicated tables that are currently in readonly state due to re-initialization after ZooKeeper session loss or due to startup without ZooKeeper configured.
RefreshableViews	Number materialized views with periodic refreshing (REFRESH)
RefreshingViews	Number of materialized views currently executing a refresh
RemoteRead	Number of read with remote reader in fly
ReplicaReady	Indicates if the replica is ready for queries: 0 = no, 1 = yes
ReplicatedChecks	Number of data parts checking for consistency
ReplicatedFetch	Number of data parts being fetched from replica
ReplicatedSend	Number of data parts being sent to replicas
RestartReplicaThreads	Number of threads in the RESTART REPLICA thread pool.
RestartReplicaThreadsActive	Number of threads in the RESTART REPLICA thread pool running a task.
RestartReplicaThreadsScheduled	Number of queued or active jobs in the RESTART REPLICA thread pool.
RestoreThreads	Number of threads in the thread pool for RESTORE.
RestoreThreadsActive	Number of threads in the thread pool for RESTORE running a task.
RestoreThreadsScheduled	Number of queued or active jobs for RESTORE.
Revision	Revision of the server. It is a number incremented for every release or release candidate except patch releases.
S3CachedCredentialsProviders	Total number of cached credentials providers
S3Requests	S3 requests count
SchedulerIOReadScheduled	Number of IO reads are being scheduled currently
SchedulerIOWriteScheduled	Number of IO writes are being scheduled currently
SendExternalTables	Number of connections that are sending data for external tables to remote servers. External tables are used to implement GLOBAL IN and GLOBAL JOIN operators with distributed subqueries.
SendScalars	Number of connections that are sending data for scalars to remote servers.
SharedCatalogDropDetachLocalTablesErrors	Number of errors that occurred when attempting to drop or detach local tables in Shared Catalog.
SharedCatalogDropLocalThreads	Number of threads in the threadpool for drop of local tables in Shared Catalog.
SharedCatalogDropLocalThreadsActive	Number of active threads in the threadpool for drop of local tables in Shared Catalog.
SharedCatalogDropLocalThreadsScheduled	Number of queued or active jobs in the threadpool for drop of local tables in Shared Catalog.
SharedCatalogDropZooKeeperThreads	Number of threads in the threadpool for drop of object in ZooKeeper in Shared Catalog.
SharedCatalogDropZooKeeperThreadsActive	Number of active threads in the threadpool for drop of object in ZooKeeper in Shared Catalog.
SharedCatalogDropZooKeeperThreadsScheduled	Number of queued or active jobs in the threadpool for drop of object in ZooKeeper in Shared Catalog.
SharedCatalogNumberOfObjectsInState	Number of objects in the current state of Shared Catalog.
SharedCatalogStateApplicationThreads	Number of threads in the threadpool for state application in Shared Catalog.
SharedCatalogStateApplicationThreadsActive	Number of active threads in the threadpool for state application in Shared Catalog.
SharedCatalogStateApplicationThreadsScheduled	Number of queued or active jobs in the threadpool for state application in Shared Catalog.
SharedDatabaseCatalogTablesInLocalDropDetachQueue	Number of tables in the queue for local drop or detach in Shared Catalog.
SharedMergeTreeAssignedCurrentParts	Number of parts locked by merge or mutation
SharedMergeTreeBrokenCondemnedPartsInKeeper	How many broken condemned part records stored in keeper
SharedMergeTreeCondemnedPartsInKeeper	How many condemned part records stored in keeper
SharedMergeTreeFetch	Number of fetches in progress
SharedMergeTreeMaxActiveReplicas	The maximum number of active replicas registered in Keeper
SharedMergeTreeMaxInactiveReplicas	The maximum number of inactive replicas registered in Keeper
SharedMergeTreeMaxPartitions	The maximum number of partitions registered in Keeper across all SharedMergeTree tables
SharedMergeTreeMaxReplicas	The maximum number of replicas registered in Keeper across all tables. Note it might not be a sum of SharedMergeTreeMaxActiveReplicas and SharedMergeTreeMaxInactiveReplicas
SharedMergeTreeMinActiveReplicas	The minimum number of active replicas registered in Keeper
SharedMergeTreeMinInactiveReplicas	The minimum number of inactive replicas registered in Keeper
SharedMergeTreeMinPartitions	The minimum number of partitions registered in Keeper across all SharedMergeTree tables
SharedMergeTreeMinReplicas	The minimum number of replicas registered in Keeper across all tables. Note it might not be a sum of SharedMergeTreeMinActiveReplicas and SharedMergeTreeMinInactiveReplicas
SharedMergeTreeOutdatedPartsInKeeper	How many outdated part records stored in keeper
SharedMergeTreeThreads	Number of threads in the thread pools in internals of SharedMergeTree
SharedMergeTreeThreadsActive	Number of threads in the thread pools in internals of SharedMergeTree running a task
SharedMergeTreeThreadsScheduled	Number of queued or active threads in the thread pools in internals of SharedMergeTree
StartupScriptsExecutionState	State of startup scripts execution: 0 = not finished, 1 = success, 2 = failure.
StartupSystemTablesThreads	Number of threads in the StartupSystemTables thread pool.
StartupSystemTablesThreadsActive	Number of threads in the StartupSystemTables thread pool running a task.
StartupSystemTablesThreadsScheduled	Number of queued or active jobs in the StartupSystemTables thread pool.
StatelessWorkerThreads	Number of threads in the stateless worker thread pool.
StatelessWorkerThreadsActive	Number of threads in the stateless worker thread pool running a task.
StatelessWorkerThreadsScheduled	Number of queued or active jobs in the stateless worker thread pool.
StorageBufferBytes	Number of bytes in buffers of Buffer tables
StorageBufferFlushThreads	Number of threads for background flushes in StorageBuffer
StorageBufferFlushThreadsActive	Number of threads for background flushes in StorageBuffer running a task
StorageBufferFlushThreadsScheduled	Number of queued or active threads for background flushes in StorageBuffer
StorageBufferRows	Number of rows in buffers of Buffer tables
StorageConnectionsStored	Total count of sessions stored in the session pool for storages
StorageConnectionsTotal	Total count of all sessions: stored in the pool and actively used right now for storages
StorageDistributedThreads	Number of threads in the StorageDistributed thread pool.
StorageDistributedThreadsActive	Number of threads in the StorageDistributed thread pool running a task.
StorageDistributedThreadsScheduled	Number of queued or active jobs in the StorageDistributed thread pool.
StorageHiveThreads	Number of threads in the StorageHive thread pool.
StorageHiveThreadsActive	Number of threads in the StorageHive thread pool running a task.
StorageHiveThreadsScheduled	Number of queued or active jobs in the StorageHive thread pool.
StorageObjectStorageThreads	Number of threads in the remote table engines thread pools.
StorageObjectStorageThreadsActive	Number of threads in the remote table engines thread pool running a task.
StorageObjectStorageThreadsScheduled	Number of queued or active jobs in remote table engines thread pool.
StorageS3Threads	Number of threads in the StorageS3 thread pool.
StorageS3ThreadsActive	Number of threads in the StorageS3 thread pool running a task.
StorageS3ThreadsScheduled	Number of queued or active jobs in the StorageS3 thread pool.
SystemDatabaseReplicasThreads	Number of threads in the system.database_replicas thread pool.
SystemDatabaseReplicasThreadsActive	Number of threads in the system.database_replicas thread pool running a task.
SystemDatabaseReplicasThreadsScheduled	Number of queued or active jobs in the system.database_replicas thread pool.
SystemReplicasThreads	Number of threads in the system.replicas thread pool.
SystemReplicasThreadsActive	Number of threads in the system.replicas thread pool running a task.
SystemReplicasThreadsScheduled	Number of queued or active jobs in the system.replicas thread pool.
TCPConnection	Number of connections to TCP server (clients with native interface), also included server-server distributed query connections
TablesLoaderBackgroundThreads	Number of threads in the tables loader background thread pool.
TablesLoaderBackgroundThreadsActive	Number of threads in the tables loader background thread pool running a task.
TablesLoaderBackgroundThreadsScheduled	Number of queued or active jobs in the tables loader background thread pool.
TablesLoaderForegroundThreads	Number of threads in the tables loader foreground thread pool.
TablesLoaderForegroundThreadsActive	Number of threads in the tables loader foreground thread pool running a task.
TablesLoaderForegroundThreadsScheduled	Number of queued or active jobs in the tables loader foreground thread pool.
TablesToDropQueueSize	Number of dropped tables, that are waiting for background data removal.
TaskTrackerThreads	Number of threads used by the distributed query remote task tracker.
TaskTrackerThreadsActive	Number of threads in the distributed query remote task tracker thread pool running a task.
TaskTrackerThreadsScheduled	Number of queued or active jobs in the distributed query remote task tracker thread pool.
TemporaryFilesForAggregation	Number of temporary files created for external aggregation
TemporaryFilesForJoin	Number of temporary files created for JOIN
TemporaryFilesForMerge	Number of temporary files for vertical merge
TemporaryFilesForSort	Number of temporary files created for external sorting
TemporaryFilesUnknown	Number of temporary files created without known purpose
TextIndexHeaderCacheBytes	Size of the text index header cache in bytes
TextIndexHeaderCacheCells	Number of entries in text index header cache
TextIndexPostingsCacheBytes	Size of the text index posting lists cache in bytes
TextIndexPostingsCacheCells	Number of entries in the text index posting lists cache
TextIndexTokensCacheBytes	Size of the text index tokens cache in bytes
TextIndexTokensCacheCells	Number of entries in the text index tokens cache
ThreadPoolFSReaderThreads	Number of threads in the thread pool for local_filesystem_read_method=threadpool.
ThreadPoolFSReaderThreadsActive	Number of threads in the thread pool for local_filesystem_read_method=threadpool running a task.
ThreadPoolFSReaderThreadsScheduled	Number of queued or active jobs in the thread pool for local_filesystem_read_method=threadpool.
ThreadPoolRemoteFSReaderThreads	Number of threads in the thread pool for remote_filesystem_read_method=threadpool.
ThreadPoolRemoteFSReaderThreadsActive	Number of threads in the thread pool for remote_filesystem_read_method=threadpool running a task.
ThreadPoolRemoteFSReaderThreadsScheduled	Number of queued or active jobs in the thread pool for remote_filesystem_read_method=threadpool.
ThreadsInOvercommitTracker	Number of waiting threads inside of OvercommitTracker
TotalTemporaryFiles	Number of temporary files created
UncompressedCacheBytes	Total size of uncompressed cache in bytes. Uncompressed cache does not usually improve the performance and should be mostly avoided
UncompressedCacheCells	Total number of entries in the uncompressed cache. Each entry represents a decompressed block of data. Uncompressed cache does not usually improve performance and should be mostly avoided
VectorSimilarityIndexCacheBytes	Size of the vector similarity index cache in bytes
VectorSimilarityIndexCacheCells	Number of entries in the vector similarity index cache
VersionInteger	Version of the server in a single integer number in base-1000. For example, version 11.22.33 is translated to 11022033.
Write	Number of write (write, pwrite, io_getevents, etc.) syscalls in fly
ZooKeeperConnectionLossStartedTimestampSeconds	Unix timestamp in seconds when ZooKeeper connection was lost, or 0 if connected successfully.
ZooKeeperRequest	Number of requests to ZooKeeper in fly.
ZooKeeperSession	Number of sessions (connections) to ZooKeeper. Should be no more than one, because using more than one connection to ZooKeeper may lead to bugs due to lack of linearizability (stale reads) that ZooKeeper consistency model allows.
ZooKeeperSessionExpired	Number of expired global ZooKeeper sessions.
ZooKeeperWatch	Number of watches (event subscriptions) in ZooKeeper.

See Also

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

Metric descriptions​

Metric descriptions