system.metrics

Size of ColumnsDescriptions cache (per-table cache)

### CompiledExpressionCacheBytes[​](#compiledexpressioncachebytes "Direct link to CompiledExpressionCacheBytes")

Total bytes used for the cache of JIT-compiled code

### CompiledExpressionCacheCount[​](#compiledexpressioncachecount "Direct link to CompiledExpressionCacheCount")

Total entries in the cache of JIT-compiled code

### Compressing[​](#compressing "Direct link to Compressing")

Number of compress operations using internal compression codecs

### CompressionThread[​](#compressionthread "Direct link to CompressionThread")

Number of threads in compression thread pools.

### CompressionThreadActive[​](#compressionthreadactive "Direct link to CompressionThreadActive")

Number of threads in compression thread pools running a task.

### CompressionThreadScheduled[​](#compressionthreadscheduled "Direct link to CompressionThreadScheduled")

Number of queued or active jobs in compression thread pools.

### ConcurrencyControlAcquired[​](#concurrencycontrolacquired "Direct link to ConcurrencyControlAcquired")

Total number of acquired CPU slots

### ConcurrencyControlAcquiredNonCompeting[​](#concurrencycontrolacquirednoncompeting "Direct link to ConcurrencyControlAcquiredNonCompeting")

Total number of acquired CPU slots that are not considered competing (the first thread if fair\_round\_robin scheduler is in use)

### ConcurrencyControlPreempted[​](#concurrencycontrolpreempted "Direct link to ConcurrencyControlPreempted")

Total number of preempted threads waiting for CPU slot

### ConcurrencyControlScheduled[​](#concurrencycontrolscheduled "Direct link to ConcurrencyControlScheduled")

Total number of CPU slot requests are being scheduled currently

### ConcurrencyControlSoftLimit[​](#concurrencycontrolsoftlimit "Direct link to ConcurrencyControlSoftLimit")

Value of soft limit on number of CPU slots

### ConcurrentHashJoinPoolThreads[​](#concurrenthashjoinpoolthreads "Direct link to ConcurrentHashJoinPoolThreads")

Number of threads in the thread pool for concurrent hash join.

### ConcurrentHashJoinPoolThreadsActive[​](#concurrenthashjoinpoolthreadsactive "Direct link to ConcurrentHashJoinPoolThreadsActive")

Number of threads in the thread pool for concurrent hash join running a task.

### ConcurrentHashJoinPoolThreadsScheduled[​](#concurrenthashjoinpoolthreadsscheduled "Direct link to ConcurrentHashJoinPoolThreadsScheduled")

Number of queued or active jobs in the thread pool for concurrent hash join.

### ConcurrentQueryAcquired[​](#concurrentqueryacquired "Direct link to ConcurrentQueryAcquired")

Total number of acquired query slots

### ConcurrentQueryScheduled[​](#concurrentqueryscheduled "Direct link to ConcurrentQueryScheduled")

Total number of query slot requests are being scheduled currently

### ContextLockWait[​](#contextlockwait "Direct link to ContextLockWait")

Number of threads waiting for lock in Context. This is global lock.

### CoordinatedMergesCoordinatorAssignedMerges[​](#coordinatedmergescoordinatorassignedmerges "Direct link to CoordinatedMergesCoordinatorAssignedMerges")

Number of assigned merges in merge coordinator state.

### CoordinatedMergesCoordinatorRunningMerges[​](#coordinatedmergescoordinatorrunningmerges "Direct link to CoordinatedMergesCoordinatorRunningMerges")

Number of running merges visible for merge coordinator.

### CoordinatedMergesWorkerAssignedMerges[​](#coordinatedmergesworkerassignedmerges "Direct link to CoordinatedMergesWorkerAssignedMerges")

Number of assigned merges in merge worker state.

### CreatedTimersInQueryProfiler[​](#createdtimersinqueryprofiler "Direct link to CreatedTimersInQueryProfiler")

Number of Created thread local timers in QueryProfiler

### DDLWorkerThreads[​](#ddlworkerthreads "Direct link to DDLWorkerThreads")

Number of threads in the DDLWorker thread pool for ON CLUSTER queries.

### DDLWorkerThreadsActive[​](#ddlworkerthreadsactive "Direct link to DDLWorkerThreadsActive")

Number of threads in the DDLWORKER thread pool for ON CLUSTER queries running a task.

### DDLWorkerThreadsScheduled[​](#ddlworkerthreadsscheduled "Direct link to DDLWorkerThreadsScheduled")

Number of queued or active jobs in the DDLWORKER thread pool for ON CLUSTER queries.

### DNSAddressesCacheBytes[​](#dnsaddressescachebytes "Direct link to DNSAddressesCacheBytes")

Size of the DNS addresses cache in bytes

### DNSAddressesCacheSize[​](#dnsaddressescachesize "Direct link to DNSAddressesCacheSize")

Number of cached DNS addresses

### DNSHostsCacheBytes[​](#dnshostscachebytes "Direct link to DNSHostsCacheBytes")

Size of the DNS hosts cache in bytes

### DNSHostsCacheSize[​](#dnshostscachesize "Direct link to DNSHostsCacheSize")

Number of cached DNS hosts

### DatabaseBackupThreads[​](#databasebackupthreads "Direct link to DatabaseBackupThreads")

Number of threads in the DatabaseBackup thread pool.

### DatabaseBackupThreadsActive[​](#databasebackupthreadsactive "Direct link to DatabaseBackupThreadsActive")

Number of threads in the DatabaseBackup thread pool running a task.

### DatabaseBackupThreadsScheduled[​](#databasebackupthreadsscheduled "Direct link to DatabaseBackupThreadsScheduled")

Number of queued or active jobs in the DatabaseBackup thread pool.

### DatabaseCatalogThreads[​](#databasecatalogthreads "Direct link to DatabaseCatalogThreads")

Number of threads in the DatabaseCatalog thread pool.

### DatabaseCatalogThreadsActive[​](#databasecatalogthreadsactive "Direct link to DatabaseCatalogThreadsActive")

Number of threads in the DatabaseCatalog thread pool running a task.

### DatabaseCatalogThreadsScheduled[​](#databasecatalogthreadsscheduled "Direct link to DatabaseCatalogThreadsScheduled")

Number of queued or active jobs in the DatabaseCatalog thread pool.

### DatabaseOnDiskThreads[​](#databaseondiskthreads "Direct link to DatabaseOnDiskThreads")

Number of threads in the DatabaseOnDisk thread pool.

### DatabaseOnDiskThreadsActive[​](#databaseondiskthreadsactive "Direct link to DatabaseOnDiskThreadsActive")

Number of threads in the DatabaseOnDisk thread pool running a task.

### DatabaseOnDiskThreadsScheduled[​](#databaseondiskthreadsscheduled "Direct link to DatabaseOnDiskThreadsScheduled")

Number of queued or active jobs in the DatabaseOnDisk thread pool.

### DatabaseReplicatedCreateTablesThreads[​](#databasereplicatedcreatetablesthreads "Direct link to DatabaseReplicatedCreateTablesThreads")

Number of threads in the threadpool for table creation in DatabaseReplicated.

### DatabaseReplicatedCreateTablesThreadsActive[​](#databasereplicatedcreatetablesthreadsactive "Direct link to DatabaseReplicatedCreateTablesThreadsActive")

Number of active threads in the threadpool for table creation in DatabaseReplicated.

### DatabaseReplicatedCreateTablesThreadsScheduled[​](#databasereplicatedcreatetablesthreadsscheduled "Direct link to DatabaseReplicatedCreateTablesThreadsScheduled")

Number of queued or active jobs in the threadpool for table creation in DatabaseReplicated.

### Decompressing[​](#decompressing "Direct link to Decompressing")

Number of decompress operations using internal compression codecs

### DelayedInserts[​](#delayedinserts "Direct link to DelayedInserts")

Number of INSERT queries that are throttled due to high number of active data parts for partition in a MergeTree table.

### DeltaLakeSnapshotCacheSizeElements[​](#deltalakesnapshotcachesizeelements "Direct link to DeltaLakeSnapshotCacheSizeElements")

Size in elements of DeltaLake snapshot cache.

### DestroyAggregatesThreads[​](#destroyaggregatesthreads "Direct link to DestroyAggregatesThreads")

Number of threads in the thread pool for destroy aggregate states.

### DestroyAggregatesThreadsActive[​](#destroyaggregatesthreadsactive "Direct link to DestroyAggregatesThreadsActive")

Number of threads in the thread pool for destroy aggregate states running a task.

### DestroyAggregatesThreadsScheduled[​](#destroyaggregatesthreadsscheduled "Direct link to DestroyAggregatesThreadsScheduled")

Number of queued or active jobs in the thread pool for destroy aggregate states.