system.metrics

Number of named collections

### NetworkReceive[​](#networkreceive "Direct link to NetworkReceive")

Number of threads receiving data from network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.

### NetworkSend[​](#networksend "Direct link to NetworkSend")

Number of threads sending data to network. Only ClickHouse-related network interaction is included, not by 3rd party libraries.

### ObjectStorageAzureThreads[​](#objectstorageazurethreads "Direct link to ObjectStorageAzureThreads")

Number of threads in the AzureObjectStorage thread pool.

### ObjectStorageAzureThreadsActive[​](#objectstorageazurethreadsactive "Direct link to ObjectStorageAzureThreadsActive")

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

### ObjectStorageAzureThreadsScheduled[​](#objectstorageazurethreadsscheduled "Direct link to ObjectStorageAzureThreadsScheduled")

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

### ObjectStorageQueueMetadataCacheSizeBytes[​](#objectstoragequeuemetadatacachesizebytes "Direct link to ObjectStorageQueueMetadataCacheSizeBytes")

Size in bytes of ObjectStorageQueue metadata cache.

### ObjectStorageQueueMetadataCacheSizeElements[​](#objectstoragequeuemetadatacachesizeelements "Direct link to ObjectStorageQueueMetadataCacheSizeElements")

Size in elements of ObjectStorageQueue metadata cache.

### ObjectStorageQueueRegisteredServers[​](#objectstoragequeueregisteredservers "Direct link to ObjectStorageQueueRegisteredServers")

Number of registered servers in StorageS3(Azure)Queue

### ObjectStorageQueueShutdownThreads[​](#objectstoragequeueshutdownthreads "Direct link to ObjectStorageQueueShutdownThreads")

Number of threads in object storage queue shutdown pool.

### ObjectStorageQueueShutdownThreadsActive[​](#objectstoragequeueshutdownthreadsactive "Direct link to ObjectStorageQueueShutdownThreadsActive")

Number of threads in object storage queue shutdown pool running a task.

### ObjectStorageQueueShutdownThreadsScheduled[​](#objectstoragequeueshutdownthreadsscheduled "Direct link to ObjectStorageQueueShutdownThreadsScheduled")

Number of queued or active jobs in object storage queue shutdown pool.

### ObjectStorageS3Threads[​](#objectstorages3threads "Direct link to ObjectStorageS3Threads")

Number of threads in the S3ObjectStorage thread pool.

### ObjectStorageS3ThreadsActive[​](#objectstorages3threadsactive "Direct link to ObjectStorageS3ThreadsActive")

Number of threads in the S3ObjectStorage thread pool running a task.

### ObjectStorageS3ThreadsScheduled[​](#objectstorages3threadsscheduled "Direct link to ObjectStorageS3ThreadsScheduled")

Number of queued or active jobs in the S3ObjectStorage thread pool.

### OpenFileForRead[​](#openfileforread "Direct link to OpenFileForRead")

Number of files open for reading

### OpenFileForWrite[​](#openfileforwrite "Direct link to OpenFileForWrite")

Number of files open for writing

### OutdatedPartsLoadingThreads[​](#outdatedpartsloadingthreads "Direct link to OutdatedPartsLoadingThreads")

Number of threads in the threadpool for loading Outdated data parts.

### OutdatedPartsLoadingThreadsActive[​](#outdatedpartsloadingthreadsactive "Direct link to OutdatedPartsLoadingThreadsActive")

Number of active threads in the threadpool for loading Outdated data parts.

### OutdatedPartsLoadingThreadsScheduled[​](#outdatedpartsloadingthreadsscheduled "Direct link to OutdatedPartsLoadingThreadsScheduled")

Number of queued or active jobs in the threadpool for loading Outdated data parts.

### PageCacheBytes[​](#pagecachebytes "Direct link to PageCacheBytes")

Total size of userspace page cache in bytes

### PageCacheCells[​](#pagecachecells "Direct link to PageCacheCells")

Total number of entries in the userspace page cache

### ParallelCompressedWriteBufferThreads[​](#parallelcompressedwritebufferthreads "Direct link to ParallelCompressedWriteBufferThreads")

Number of threads in all instances of ParallelCompressedWriteBuffer - these threads are doing parallel compression and writing

### ParallelCompressedWriteBufferWait[​](#parallelcompressedwritebufferwait "Direct link to ParallelCompressedWriteBufferWait")

Number of threads in all instances of ParallelCompressedWriteBuffer that are currently waiting for buffer to become available for writing

### ParallelFormattingOutputFormatThreads[​](#parallelformattingoutputformatthreads "Direct link to ParallelFormattingOutputFormatThreads")

Number of threads in the ParallelFormattingOutputFormatThreads thread pool.

### ParallelFormattingOutputFormatThreadsActive[​](#parallelformattingoutputformatthreadsactive "Direct link to ParallelFormattingOutputFormatThreadsActive")

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

### ParallelFormattingOutputFormatThreadsScheduled[​](#parallelformattingoutputformatthreadsscheduled "Direct link to ParallelFormattingOutputFormatThreadsScheduled")

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

### ParallelWithQueryActiveThreads[​](#parallelwithqueryactivethreads "Direct link to ParallelWithQueryActiveThreads")

Number of active threads in the threadpool for processing PARALLEL WITH queries.

### ParallelWithQueryScheduledThreads[​](#parallelwithqueryscheduledthreads "Direct link to ParallelWithQueryScheduledThreads")

Number of queued or active jobs in the threadpool for processing PARALLEL WITH queries.

### ParallelWithQueryThreads[​](#parallelwithquerythreads "Direct link to ParallelWithQueryThreads")

Number of threads in the threadpool for processing PARALLEL WITH queries.

### ParquetEncoderThreads[​](#parquetencoderthreads "Direct link to ParquetEncoderThreads")

Number of threads in ParquetBlockOutputFormat thread pool.

### ParquetEncoderThreadsActive[​](#parquetencoderthreadsactive "Direct link to ParquetEncoderThreadsActive")

Number of threads in ParquetBlockOutputFormat thread pool running a task.

### ParquetEncoderThreadsScheduled[​](#parquetencoderthreadsscheduled "Direct link to ParquetEncoderThreadsScheduled")

Number of queued or active jobs in ParquetBlockOutputFormat thread pool.

### ParquetMetadataCacheBytes[​](#parquetmetadatacachebytes "Direct link to ParquetMetadataCacheBytes")

Size of the Parquet metadata cache in bytes

### ParquetMetadataCacheFiles[​](#parquetmetadatacachefiles "Direct link to ParquetMetadataCacheFiles")

Number of cached files in the Parquet metadata cache

### PartMutation[​](#partmutation "Direct link to PartMutation")

Number of mutations (ALTER DELETE/UPDATE)

### PartsActive[​](#partsactive "Direct link to PartsActive")

Active data part, used by current and upcoming SELECTs.

### PartsCommitted[​](#partscommitted "Direct link to PartsCommitted")

Deprecated. See PartsActive.

### PartsCompact[​](#partscompact "Direct link to PartsCompact")

Compact parts.

### PartsDeleteOnDestroy[​](#partsdeleteondestroy "Direct link to PartsDeleteOnDestroy")

Part was moved to another disk and should be deleted in own destructor.

### PartsDeleting[​](#partsdeleting "Direct link to PartsDeleting")

Not active data part with identity refcounter, it is deleting right now by a cleaner.

### PartsOutdated[​](#partsoutdated "Direct link to PartsOutdated")

Not active data part, but could be used by only current SELECTs, could be deleted after SELECTs finishes.

### PartsPreActive[​](#partspreactive "Direct link to PartsPreActive")

The part is in data\_parts, but not used for SELECTs.

### PartsPreCommitted[​](#partsprecommitted "Direct link to PartsPreCommitted")

Deprecated. See PartsPreActive.

### PartsTemporary[​](#partstemporary "Direct link to PartsTemporary")

The part is generating now, it is not in data\_parts list.

### PartsWide[​](#partswide "Direct link to PartsWide")

Wide parts.

### PendingAsyncInsert[​](#pendingasyncinsert "Direct link to PendingAsyncInsert")

Number of asynchronous inserts that are waiting for flush.

### PolygonDictionaryThreads[​](#polygondictionarythreads "Direct link to PolygonDictionaryThreads")

Number of threads in the threadpool for polygon dictionaries.