system.metrics

### BackgroundFetchesPoolSize[​](#backgroundfetchespoolsize "Direct link to BackgroundFetchesPoolSize")

Limit on number of simultaneous fetches in an associated background pool

### BackgroundFetchesPoolTask[​](#backgroundfetchespooltask "Direct link to BackgroundFetchesPoolTask")

Number of active fetches in an associated background pool

### BackgroundMergesAndMutationsPoolSize[​](#backgroundmergesandmutationspoolsize "Direct link to BackgroundMergesAndMutationsPoolSize")

Limit on number of active merges and mutations in an associated background pool

### BackgroundMergesAndMutationsPoolTask[​](#backgroundmergesandmutationspooltask "Direct link to BackgroundMergesAndMutationsPoolTask")

Number of active merges and mutations in an associated background pool

### BackgroundMessageBrokerSchedulePoolSize[​](#backgroundmessagebrokerschedulepoolsize "Direct link to BackgroundMessageBrokerSchedulePoolSize")

Limit on number of tasks in BackgroundMessageBrokerSchedulePool for message streaming

### BackgroundMessageBrokerSchedulePoolTask[​](#backgroundmessagebrokerschedulepooltask "Direct link to BackgroundMessageBrokerSchedulePoolTask")

Number of active tasks in BackgroundMessageBrokerSchedulePool for message streaming

### BackgroundMovePoolSize[​](#backgroundmovepoolsize "Direct link to BackgroundMovePoolSize")

Limit on number of tasks in BackgroundProcessingPool for moves

### BackgroundMovePoolTask[​](#backgroundmovepooltask "Direct link to BackgroundMovePoolTask")

Number of active tasks in BackgroundProcessingPool for moves

### BackgroundSchedulePoolSize[​](#backgroundschedulepoolsize "Direct link to 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[​](#backgroundschedulepooltask "Direct link to 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[​](#backupsiothreads "Direct link to BackupsIOThreads")

Number of threads in the BackupsIO thread pool.

### BackupsIOThreadsActive[​](#backupsiothreadsactive "Direct link to BackupsIOThreadsActive")

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

### BackupsIOThreadsScheduled[​](#backupsiothreadsscheduled "Direct link to BackupsIOThreadsScheduled")

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

### BackupsThreads[​](#backupsthreads "Direct link to BackupsThreads")

Number of threads in the thread pool for BACKUP.

### BackupsThreadsActive[​](#backupsthreadsactive "Direct link to BackupsThreadsActive")

Number of threads in thread pool for BACKUP running a task.

### BackupsThreadsScheduled[​](#backupsthreadsscheduled "Direct link to BackupsThreadsScheduled")

Number of queued or active jobs for BACKUP.

### BcryptCacheBytes[​](#bcryptcachebytes "Direct link to BcryptCacheBytes")

Total size of the bcrypt authentication cache in bytes

### BcryptCacheSize[​](#bcryptcachesize "Direct link to BcryptCacheSize")

Total number of entries in the bcrypt authentication cache

### BlobCopierThreads[​](#blobcopierthreads "Direct link to BlobCopierThreads")

Number of threads in the thread pool of the object storage disk background replication process

### BlobCopierThreadsActive[​](#blobcopierthreadsactive "Direct link to BlobCopierThreadsActive")

Number of threads in the thread pool of the object storage disk background replication process running a task

### BlobCopierThreadsScheduled[​](#blobcopierthreadsscheduled "Direct link to BlobCopierThreadsScheduled")

Number of queued or active tasks in the thread pool of the object storage disk background replication process

### BlobKillerThreads[​](#blobkillerthreads "Direct link to BlobKillerThreads")

Number of threads in the thread pool of the object storage disk background removal process

### BlobKillerThreadsActive[​](#blobkillerthreadsactive "Direct link to BlobKillerThreadsActive")

Number of threads in the thread pool of the object storage disk background removal process running a task

### BlobKillerThreadsScheduled[​](#blobkillerthreadsscheduled "Direct link to BlobKillerThreadsScheduled")

Number of queued or active tasks in the thread pool of the object storage disk background removal process

### BrokenDisks[​](#brokendisks "Direct link to BrokenDisks")

Number of disks disks that were marked as broken during disk check.

### BrokenDistributedBytesToInsert[​](#brokendistributedbytestoinsert "Direct link to 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[​](#brokendistributedfilestoinsert "Direct link to 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[​](#buildvectorsimilarityindexthreads "Direct link to BuildVectorSimilarityIndexThreads")

Number of threads in the build vector similarity index thread pool.

### BuildVectorSimilarityIndexThreadsActive[​](#buildvectorsimilarityindexthreadsactive "Direct link to BuildVectorSimilarityIndexThreadsActive")

Number of threads in the build vector similarity index thread pool running a task.

### BuildVectorSimilarityIndexThreadsScheduled[​](#buildvectorsimilarityindexthreadsscheduled "Direct link to BuildVectorSimilarityIndexThreadsScheduled")

Number of queued or active jobs in the build vector similarity index thread pool.

### CacheDetachedFileSegments[​](#cachedetachedfilesegments "Direct link to CacheDetachedFileSegments")

Number of existing detached cache file segments

### CacheDictionaryThreads[​](#cachedictionarythreads "Direct link to CacheDictionaryThreads")

Number of threads in the CacheDictionary thread pool.

### CacheDictionaryThreadsActive[​](#cachedictionarythreadsactive "Direct link to CacheDictionaryThreadsActive")

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

### CacheDictionaryThreadsScheduled[​](#cachedictionarythreadsscheduled "Direct link to CacheDictionaryThreadsScheduled")

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

### CacheDictionaryUpdateQueueBatches[​](#cachedictionaryupdatequeuebatches "Direct link to CacheDictionaryUpdateQueueBatches")

Number of 'batches' (a set of keys) in update queue in CacheDictionaries.

### CacheDictionaryUpdateQueueKeys[​](#cachedictionaryupdatequeuekeys "Direct link to CacheDictionaryUpdateQueueKeys")

Exact number of keys in update queue in CacheDictionaries.

### CacheFileSegments[​](#cachefilesegments "Direct link to CacheFileSegments")

Number of existing cache file segments

### CacheWarmerBytesInProgress[​](#cachewarmerbytesinprogress "Direct link to CacheWarmerBytesInProgress")

Total size of remote file segments waiting to be asynchronously loaded into filesystem cache.

### ColumnsDescriptionsCacheSize[​](#columnsdescriptionscachesize "Direct link to ColumnsDescriptionsCacheSize")

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.