system.metrics

Number of temporary files created for JOIN

### TemporaryFilesForMerge[​](#temporaryfilesformerge "Direct link to TemporaryFilesForMerge")

Number of temporary files for vertical merge

### TemporaryFilesForSort[​](#temporaryfilesforsort "Direct link to TemporaryFilesForSort")

Number of temporary files created for external sorting

### TemporaryFilesUnknown[​](#temporaryfilesunknown "Direct link to TemporaryFilesUnknown")

Number of temporary files created without known purpose

### TextIndexHeaderCacheBytes[​](#textindexheadercachebytes "Direct link to TextIndexHeaderCacheBytes")

Size of the text index header cache in bytes

### TextIndexHeaderCacheCells[​](#textindexheadercachecells "Direct link to TextIndexHeaderCacheCells")

Number of entries in text index header cache

### TextIndexPostingsCacheBytes[​](#textindexpostingscachebytes "Direct link to TextIndexPostingsCacheBytes")

Size of the text index posting lists cache in bytes

### TextIndexPostingsCacheCells[​](#textindexpostingscachecells "Direct link to TextIndexPostingsCacheCells")

Number of entries in the text index posting lists cache

### TextIndexTokensCacheBytes[​](#textindextokenscachebytes "Direct link to TextIndexTokensCacheBytes")

Size of the text index tokens cache in bytes

### TextIndexTokensCacheCells[​](#textindextokenscachecells "Direct link to TextIndexTokensCacheCells")

Number of entries in the text index tokens cache

### ThreadPoolFSReaderThreads[​](#threadpoolfsreaderthreads "Direct link to ThreadPoolFSReaderThreads")

Number of threads in the thread pool for local\_filesystem\_read\_method=threadpool.

### ThreadPoolFSReaderThreadsActive[​](#threadpoolfsreaderthreadsactive "Direct link to ThreadPoolFSReaderThreadsActive")

Number of threads in the thread pool for local\_filesystem\_read\_method=threadpool running a task.

### ThreadPoolFSReaderThreadsScheduled[​](#threadpoolfsreaderthreadsscheduled "Direct link to ThreadPoolFSReaderThreadsScheduled")

Number of queued or active jobs in the thread pool for local\_filesystem\_read\_method=threadpool.

### ThreadPoolRemoteFSReaderThreads[​](#threadpoolremotefsreaderthreads "Direct link to ThreadPoolRemoteFSReaderThreads")

Number of threads in the thread pool for remote\_filesystem\_read\_method=threadpool.

### ThreadPoolRemoteFSReaderThreadsActive[​](#threadpoolremotefsreaderthreadsactive "Direct link to ThreadPoolRemoteFSReaderThreadsActive")

Number of threads in the thread pool for remote\_filesystem\_read\_method=threadpool running a task.

### ThreadPoolRemoteFSReaderThreadsScheduled[​](#threadpoolremotefsreaderthreadsscheduled "Direct link to ThreadPoolRemoteFSReaderThreadsScheduled")

Number of queued or active jobs in the thread pool for remote\_filesystem\_read\_method=threadpool.

### ThreadsInOvercommitTracker[​](#threadsinovercommittracker "Direct link to ThreadsInOvercommitTracker")

Number of waiting threads inside of OvercommitTracker

### TotalTemporaryFiles[​](#totaltemporaryfiles "Direct link to TotalTemporaryFiles")

Number of temporary files created

### UncompressedCacheBytes[​](#uncompressedcachebytes "Direct link to UncompressedCacheBytes")

Total size of uncompressed cache in bytes. Uncompressed cache does not usually improve the performance and should be mostly avoided

### UncompressedCacheCells[​](#uncompressedcachecells "Direct link to 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[​](#vectorsimilarityindexcachebytes "Direct link to VectorSimilarityIndexCacheBytes")

Size of the vector similarity index cache in bytes

### VectorSimilarityIndexCacheCells[​](#vectorsimilarityindexcachecells "Direct link to VectorSimilarityIndexCacheCells")

Number of entries in the vector similarity index cache

### VersionInteger[​](#versioninteger "Direct link to VersionInteger")

Version of the server in a single integer number in base-1000. For example, version 11.22.33 is translated to 11022033.

### Write[​](#write "Direct link to Write")

Number of write (write, pwrite, io\_getevents, etc.) syscalls in fly

### ZooKeeperConnectionLossStartedTimestampSeconds[​](#zookeeperconnectionlossstartedtimestampseconds "Direct link to ZooKeeperConnectionLossStartedTimestampSeconds")

Unix timestamp in seconds when ZooKeeper connection was lost, or 0 if connected successfully.

### ZooKeeperRequest[​](#zookeeperrequest "Direct link to ZooKeeperRequest")

Number of requests to ZooKeeper in fly.

### ZooKeeperSession[​](#zookeepersession "Direct link to 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[​](#zookeepersessionexpired "Direct link to ZooKeeperSessionExpired")

Number of expired global ZooKeeper sessions.

### ZooKeeperWatch[​](#zookeeperwatch "Direct link to ZooKeeperWatch")

Number of watches (event subscriptions) in ZooKeeper.

**See Also**

- [system.asynchronous\_metrics](/docs/operations/system-tables/asynchronous_metrics) — Contains periodically calculated metrics.
- [system.events](/docs/operations/system-tables/events) — Contains a number of events that occurred.
- [system.metric\_log](/docs/operations/system-tables/metric_log) — Contains a history of metrics values from tables `system.metrics` and `system.events`.
- [Monitoring](/docs/operations/monitoring) — Base concepts of ClickHouse monitoring.