System Tables

--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.stack\_trace](/docs/operations/system-tables/stack_trace) System table which contains stack traces of all server threads. Allows developers to introspect the server state.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.storage\_policies](/docs/operations/system-tables/storage_policies) System table containing information about storage policies and volumes which are defined in server configuration.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.symbols](/docs/operations/system-tables/symbols) System table useful for C++ experts and ClickHouse engineers containing information for introspection of the `clickhouse` binary.| [system.table\_engines](/docs/operations/system-tables/table_engines) System table containing descriptions of table engines supported by the server and the features they support.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.tables](/docs/operations/system-tables/tables) System table containing metadata of each table that the server knows about.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.text\_log](/docs/operations/system-tables/text_log) System table containing logging entries.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.time\_zones](/docs/operations/system-tables/time_zones) System table containing a list of time zones that are supported by the ClickHouse server.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.tokenizers](/docs/operations/system-tables/tokenizers) System table which shows all available tokenizers.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.trace\_log](/docs/operations/system-tables/trace_log) System table containing stack traces collected by the sampling query profiler.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.unicode](/docs/operations/system-tables/unicode) System table containing a list of Unicode characters and their properties.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.user\_defined\_functions](/docs/operations/system-tables/user_defined_functions) System table containing loading status and configuration metadata for User-Defined Functions (UDFs).|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.user\_processes](/docs/operations/system-tables/user_processes) System table containing information useful for an overview of memory usage and ProfileEvents of users.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.users](/docs/operations/system-tables/users) System table containing a list of user accounts configured on the server.|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.view\_refreshes](/docs/operations/system-tables/view_refreshes) System table containing information about Refreshable Materialized Views.|  |  |  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.warnings](/docs/operations/system-tables/system_warnings) This table contains warning messages about clickhouse server.|  |  |  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.workloads](/docs/operations/system-tables/workloads) System table containing information for workloads residing on the local server.|  |  |  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | [system.zookeeper](/docs/operations/system-tables/zookeeper) System table which exists only if ClickHouse Keeper or ZooKeeper are configured. It exposes data from the Keeper cluster defined in the config.|  |  |  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | --- | --- | | [system.zookeeper\_connection](/docs/operations/system-tables/zookeeper_connection) System table which exists only if ZooKeeper is configured. Shows current connections to ZooKeeper (including auxiliary ZooKeepers).|  |  |  |  |  |  | | --- | --- | --- | --- | --- | --- | | [system.zookeeper\_connection\_log](/docs/operations/system-tables/zookeeper_connection_log) Shows the history of ZooKeeper connections (including auxiliary ZooKeepers).|  |  |  |  | | --- | --- | --- | --- | | [system.zookeeper\_info](/docs/operations/system-tables/zookeeper_info) System table which outputs introspection of all available keeper nodes.|  |  | | --- | --- | | [system.zookeeper\_log](/docs/operations/system-tables/zookeeper_log) System table containing information about the parameters of the request to the ZooKeeper server and the response from it. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |