system.metrics

System table containing metrics which can be calculated instantly, or have a current value.

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.

Description

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.

Aliases:

• name — Alias for metric.

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           │
└──────────────────────────────────────┴───────┴────────────────────────────────────────────────────────────────────────┘

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

IcebergSchedulePoolSize

Limit on number of tasks in the background schedule pool for Iceberg tables.

IcebergSchedulePoolTask

Number of tasks in the background schedule pool for Iceberg tables.

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

KeeperReadThreads

Number of threads in the threadpool for keeper server reads.

KeeperReadThreadsActive

Number of active threads in the threadpool for keeper server reads.

KeeperReadThreadsScheduled

Number of queued or active jobs in the threadpool for keeper server reads. Meaningless metric, the actual read tasks on this thread pool are scheduled through a different mechanism.

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. Holds primary-key indices loaded on demand when primary_key_lazy_load=1 and use_primary_key_cache=1. Allocations live in the dedicated cache jemalloc arena (jemalloc.cache_arena.*). NEVER overlaps with system.parts.primary_key_bytes_in_memory[_allocated] — a part’s index lives either in this cache (counted here) or in the part itself (counted there); never both. To get total primary-index memory across all parts, sum the two.

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.

SerializationCacheBytesInMemory

Total size of the serialization cache in bytes including only the values

SerializationCacheBytesInMemoryAllocated

Total size of the serialization cache in bytes including keys and overhead from empty slots

SerializationCacheCount

Total number of entries in the serialization cache

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.