system.metrics

Number of io\_uring SQEs in flight

### IOUringPendingEvents[​](#iouringpendingevents "Direct link to IOUringPendingEvents")

Number of io\_uring SQEs waiting to be submitted

### IOWriterThreads[​](#iowriterthreads "Direct link to IOWriterThreads")

Number of threads in the IO writer thread pool.

### IOWriterThreadsActive[​](#iowriterthreadsactive "Direct link to IOWriterThreadsActive")

Number of threads in the IO writer thread pool running a task.

### IOWriterThreadsScheduled[​](#iowriterthreadsscheduled "Direct link to IOWriterThreadsScheduled")

Number of queued or active jobs in the IO writer thread pool.

### IcebergCatalogThreads[​](#icebergcatalogthreads "Direct link to IcebergCatalogThreads")

Number of threads in the IcebergCatalog thread pool.

### IcebergCatalogThreadsActive[​](#icebergcatalogthreadsactive "Direct link to IcebergCatalogThreadsActive")

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

### IcebergCatalogThreadsScheduled[​](#icebergcatalogthreadsscheduled "Direct link to IcebergCatalogThreadsScheduled")

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

### IcebergMetadataFilesCacheBytes[​](#icebergmetadatafilescachebytes "Direct link to IcebergMetadataFilesCacheBytes")

Size of the Iceberg metadata cache in bytes

### IcebergMetadataFilesCacheFiles[​](#icebergmetadatafilescachefiles "Direct link to IcebergMetadataFilesCacheFiles")

Number of cached files in the Iceberg metadata cache

### IcebergSchedulePoolSize[​](#icebergschedulepoolsize "Direct link to IcebergSchedulePoolSize")

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

### IcebergSchedulePoolTask[​](#icebergschedulepooltask "Direct link to IcebergSchedulePoolTask")

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

### IndexMarkCacheBytes[​](#indexmarkcachebytes "Direct link to IndexMarkCacheBytes")

Total size of mark cache for secondary indices in bytes

### IndexMarkCacheFiles[​](#indexmarkcachefiles "Direct link to IndexMarkCacheFiles")

Total number of mark files cached in the mark cache for secondary indices

### IndexUncompressedCacheBytes[​](#indexuncompressedcachebytes "Direct link to 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[​](#indexuncompressedcachecells "Direct link to 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[​](#interserverconnection "Direct link to InterserverConnection")

Number of connections from other replicas to fetch parts

### IsServerShuttingDown[​](#isservershuttingdown "Direct link to IsServerShuttingDown")

Indicates if the server is shutting down: 0 = no, 1 = yes

### KafkaAssignedPartitions[​](#kafkaassignedpartitions "Direct link to KafkaAssignedPartitions")

Number of partitions Kafka tables currently assigned to

### KafkaBackgroundReads[​](#kafkabackgroundreads "Direct link to KafkaBackgroundReads")

Number of background reads currently working (populating materialized views from Kafka)

### KafkaConsumers[​](#kafkaconsumers "Direct link to KafkaConsumers")

Number of active Kafka consumers

### KafkaConsumersInUse[​](#kafkaconsumersinuse "Direct link to KafkaConsumersInUse")

Number of consumers which are currently used by direct or background reads

### KafkaConsumersWithAssignment[​](#kafkaconsumerswithassignment "Direct link to KafkaConsumersWithAssignment")

Number of active Kafka consumers which have some partitions assigned.

### KafkaLibrdkafkaThreads[​](#kafkalibrdkafkathreads "Direct link to KafkaLibrdkafkaThreads")

Number of active librdkafka threads

### KafkaProducers[​](#kafkaproducers "Direct link to KafkaProducers")

Number of active Kafka producer created

### KafkaWrites[​](#kafkawrites "Direct link to KafkaWrites")

Number of currently running inserts to Kafka

### KeeperAliveConnections[​](#keeperaliveconnections "Direct link to KeeperAliveConnections")

Number of alive connections

### KeeperOutstandingRequests[​](#keeperoutstandingrequests "Direct link to KeeperOutstandingRequests")

Number of outstanding requests

### LicenseRemainingSeconds[​](#licenseremainingseconds "Direct link to LicenseRemainingSeconds")

Remaining seconds of the license validity period.

### LocalThread[​](#localthread "Direct link to LocalThread")

Obsolete. Number of threads in local thread pools. The threads in local thread pools are taken from the global thread pool.

### LocalThreadActive[​](#localthreadactive "Direct link to LocalThreadActive")

Obsolete. Number of threads in local thread pools running a task.

### LocalThreadScheduled[​](#localthreadscheduled "Direct link to LocalThreadScheduled")

Obsolete. Number of queued or active jobs in local thread pools.

### MMapCacheCells[​](#mmapcachecells "Direct link to 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[​](#mmappedfilebytes "Direct link to MMappedFileBytes")

Sum size of mmapped file regions.

### MMappedFiles[​](#mmappedfiles "Direct link to MMappedFiles")

Total number of mmapped files.

### MarkCacheBytes[​](#markcachebytes "Direct link to MarkCacheBytes")

Total size of mark cache in bytes

### MarkCacheFiles[​](#markcachefiles "Direct link to MarkCacheFiles")

Total number of mark files cached in the mark cache

### MarksLoaderThreads[​](#marksloaderthreads "Direct link to MarksLoaderThreads")

Number of threads in thread pool for loading marks.

### MarksLoaderThreadsActive[​](#marksloaderthreadsactive "Direct link to MarksLoaderThreadsActive")

Number of threads in the thread pool for loading marks running a task.

### MarksLoaderThreadsScheduled[​](#marksloaderthreadsscheduled "Direct link to MarksLoaderThreadsScheduled")

Number of queued or active jobs in the thread pool for loading marks.

### MaxAllocatedEphemeralLockSequentialNumber[​](#maxallocatedephemerallocksequentialnumber "Direct link to MaxAllocatedEphemeralLockSequentialNumber")

The maximum sequential number allocated for ephemeral lock znodes in ZooKeeper. Primarily influenced by the block numbers.

### MaxDDLEntryID[​](#maxddlentryid "Direct link to MaxDDLEntryID")

Max processed DDL entry of DDLWorker.

### MaxPushedDDLEntryID[​](#maxpushedddlentryid "Direct link to MaxPushedDDLEntryID")

Max DDL entry of DDLWorker that pushed to zookeeper.

### MemoryTracking[​](#memorytracking "Direct link to MemoryTracking")

Total amount of memory (bytes) allocated by the server.

### MemoryTrackingUncorrected[​](#memorytrackinguncorrected "Direct link to MemoryTrackingUncorrected")

Total amount of memory (bytes) allocated by the server not corrected by RSS.

### Merge[​](#merge "Direct link to Merge")

Number of executing background merges

### MergeJoinBlocksCacheBytes[​](#mergejoinblockscachebytes "Direct link to MergeJoinBlocksCacheBytes")

Total bytes used for cached blocks in MergeJoin

### MergeJoinBlocksCacheCount[​](#mergejoinblockscachecount "Direct link to MergeJoinBlocksCacheCount")

Total cached blocks in MergeJoin

### MergeParts[​](#mergeparts "Direct link to MergeParts")

Number of source parts participating in current background merges

### MergeTreeAllRangesAnnouncementsSent[​](#mergetreeallrangesannouncementssent "Direct link to 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[​](#mergetreebackgroundexecutorthreads "Direct link to MergeTreeBackgroundExecutorThreads")

Number of threads in the MergeTreeBackgroundExecutor thread pool.