| asynchronous_insert_log | System table containing information about async inserts. Each entry represents an insert query buffered into an async insert query. |
| asynchronous_inserts | System table containing information about pending asynchronous inserts in queue. |
| asynchronous_loader | System table containing information about and status of recent asynchronous jobs (e.g. for tables which are loading). The table contains a row for every job. |
| asynchronous_metric_log | System table containing historical values for system.asynchronous_metrics, which are saved once per time interval (one second by default) |
| asynchronous_metrics | System table containing metrics that are calculated periodically in the background. For example, the amount of RAM in use. |
| azure_queue_settings | System table containing information about settings of AzureQueue tables. Available from server version 24.10. |
| backup_log | System table containing logging entries with information about BACKUP and RESTORE operations. |
| blob_storage_log | System table containing logging entries with information about various blob storage operations such as uploads and deletes. |
| build_options | System table containing information about ClickHouse server's build options. |
| clusters | System table containing information about clusters available in the config file and the servers defined in them. |
| columns | System table containing information about columns in all tables |
| contributors | System table containing information about contributors. |
| crash_log | System table containing information about stack traces for fatal errors. |
| current_roles | System table containing active roles for the current user. |
| dashboards | Contains queries used by /dashboard page accessible though the HTTP interface. useful for monitoring and troubleshooting. |
| data_skipping_indices | System table containing information about existing data skipping indices in all the tables. |
| data_type_families | System table containing information about supported data types |
| database_engines | System table containing a list of database engines supported by the server. |
| databases | System table containing information about the databases that are available to the current user. |
| detached_parts | System table containing information about detached parts of MergeTree tables |
| detached_tables | System table containing information about each detached table. |
| dictionaries | System table containing information about dictionaries |
| disks | System table containing information about disks defined in the server configuration |
| distributed_ddl_queue | System table containing information about distributed ddl queries (queries using the ON CLUSTER clause) that were executed on a cluster. |
| distribution_queue | System table containing information about local files that are in the queue to be sent to the shards. |
| dns_cache | System table containing information about cached DNS records. |
| dropped_tables | System table containing information about tables that drop table has been executed on but for which data cleanup has not yet been performed |
| dropped_tables_parts | System table containing information about parts of MergeTree dropped tables from system.dropped_tables |
| enabled_roles | System table containing all active roles at the moment, including the current role of the current user and the granted roles for the current role |
| error_log | System table containing the history of error values from table system.errors, periodically flushed to disk. |
| errors | System table containing error codes with the number of times they have been triggered. |
| events | System table containing information about the number of events that have occurred in the system. |
| functions | System table containing information about normal and aggregate functions. |
| grants | System table showing which privileges are granted to ClickHouse user accounts. |
| graphite_retentions | System table containing information about parameters graphite_rollup which are used in tables with GraphiteMergeTree type engines. |
| INFORMATION_SCHEMA | System database providing an almost standardized DBMS-agnostic view on metadata of database objects. |
| jemalloc_bins | System table containing information about memory allocations done via jemalloc allocator in different size classes (bins) aggregated from all arenas. |
| kafka_consumers | System table containing information about Kafka consumers. |
| latency_buckets | System table containing information about bucket bounds used by latency_log. |
| latency_log | Contains the history of all latency buckets, periodically flushed to disk. |
| licenses | System table containing licenses of third-party libraries that are located in the contrib directory of ClickHouse sources. |
| merge_tree_settings | System table containing information about settings for MergeTree tables. |
| merges | System table containing information about merges and part mutations currently in process for tables in the MergeTree family. |
| metric_log | System table containing history of metrics values from tables system.metrics and system.events, periodically flushed to disk. |
| metrics | System table containing metrics which can be calculated instantly, or have a current value. |
| moves | System table containing information about in-progress data part moves of MergeTree tables. Each data part movement is represented by a single row. |
| mutations | System table containing information about mutations of MergeTree tables and their progress. Each mutation command is represented by a single row. |
| numbers | System table containing a single UInt64 column named number that contains almost all the natural numbers starting from zero. |
| numbers_mt | System table similar to system.numbers but reads are parallelized and numbers can be returned in any order. |
| one | System table containing a single row with a single dummy UInt8 column containing the value 0. Similar to the DUAL table found in other DBMSs. |
| opentelemetry_span_log | System table containing information about trace spans for executed queries. |
| System Tables Overview | Overview of what system tables are and why they are useful. |
| part_log | System table containing information about events that occurred with data parts in the MergeTree family tables, such as adding or merging of data. |
| parts | |
| parts_columns | System table containing information about parts and columns of MergeTree tables. |
| processes | System table used for implementing the SHOW PROCESSLIST query. |
| processors_profile_log | System table containing profiling information on the processors level (which can be found in EXPLAIN PIPELINE) |
| processors_profile_log | System table containing information about existing projections in all tables. |
| query_cache | System table which shows the content of the query cache. |
| query_log | System table containing information about executed queries, for example, start time, duration of processing, error messages. |
| query_metric_log | System table containing a history of memory and metric values from table system.events for individual queries, periodically flushed to disk. |
| query_thread_log | System table containing information about threads that execute queries, for example, thread name, thread start time, duration of query processing. |
| query_views_log | System table containing information about the dependent views executed when running a query, for example, the view type or the execution time. |
| quota_limits | System table containing information about maximums for all intervals of all quotas. Any number of rows or zero can correspond to one quota. |
| quota_usage | System table containing formation about quota usage by the current user such as how much of the quota is used and how much is left. |
| quotas | System table containing information about quotas. |
| quotas_usage | System table containing formation about quota usage by all users. |
| replicas | System table containing information about and status of replicated tables residing on the local server. Useful for monitoring. |
| replicated_fetches | System table containing information about currently running background fetches. |
| replication_queue | System table containing information about tasks from replication queues stored in ClickHouse Keeper, or ZooKeeper, for tables in the ReplicatedMergeTree family. |
| resources | System table containing information about resources residing on the local server with one row for every resource. |
| role_grants | System table containing the role grants for users and roles. |
| roles | System table containing information about configured roles. |
| row_policies | System table containing filters for one particular table, as well as a list of roles and/or users which should use this row policy. |
| s3_queue_settings | System table containing information about the settings of S3Queue tables. Available from server version 24.10. |
| scheduler | System table containing information about and status of scheduling nodes residing on the local server. |
| schema_inference_cache | System table containing information about all cached file schemas. |
| server_settings | System table containing formation about global settings for the server, which are specified in config.xml. |
| session_log | System table containing information about all successful and failed login and logout events. |
| settings | System table containing information about session settings for current user. |
| settings_changes | System table containing information about setting changes in previous ClickHouse versions. |
| settings_profile_elements | System table which describes the content of the settings profile: constraints, roles and users that the setting applies to, parent settings profiles. |
| settings_profiles | System table which contains properties of configured setting profiles. |
| stack_trace | System table which contains stack traces of all server threads. Allows developers to introspect the server state. |
| storage_policies | System table containing information about storage policies and volumes which are defined in server configuration. |
| symbols | System table useful for C++ experts and ClickHouse engineers containing information for introspection of the clickhouse binary. |
| table_engines | System table containing descriptions of table engines supported by the server and the features they support. |
| tables | System table containing metadata of each table that the server knows about. |
| text_log | System table containing logging entries. |
| time_zones | System table containing a list of time zones that are supported by the ClickHouse server. |
| trace_log | System table containing stack traces collected by the sampling query profiler. |
| user_processes | System table containing information useful for an overview of memory usage and ProfileEvents of users. |
| users | System table containing a list of user accounts configured on the server. |
| view_refreshes | System table containing information about Refreshable Materialized Views. |
| workloads | System table containing information for workloads residing on the local server. |
| zookeeper | System table which exists only if ClickHouse Keeper or ZooKeeper are configured. It exposes data from the Keeper cluster defined in the config. |
| zookeeper_connection | System table which exists only if ZooKeeper is configured. Shows current connections to ZooKeeper (including auxiliary ZooKeepers). |
| zookeeper_log | System table containing information about the parameters of the request to the ZooKeeper server and the response from it. |