Системные таблицы

Обзор системных таблиц и их назначения.

Страница	Описание
system.constraints	System table containing information about existing constraints in all tables.
System Tables Overview	Overview of what system tables are and why they are useful.
INFORMATION_SCHEMA	System database providing an almost standardized DBMS-agnostic view on metadata of database objects.
system.aggregate_function_combinators	Contains a list of all available aggregate function combinators, which could be applied to aggregate functions and change the way they work.
system.aggregated_zookeeper_log	System table containing aggregated statistics of ZooKeeper operations grouped by session, path, operation type, component, and subrequest flag.
system.asynchronous_insert_log	System table containing information about async inserts. Each entry represents an insert query buffered into an async insert query.
system.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.
system.asynchronous_metric_log	System table containing historical values for system.asynchronous_metrics, which are saved once per time interval (one second by default)
system.asynchronous_inserts	System table containing information about pending asynchronous inserts in queue.
system.asynchronous_metrics	System table containing metrics that are calculated periodically in the background. For example, the amount of RAM in use.
system.azure_queue_settings	System table containing information about settings of AzureQueue tables. Available from server version 24.10.
system.azure_queue_metadata_cache	Contains in-memory state of AzureQueue metadata and currently processed rows per file.
system.azure_queue_log	Contains log entries with information about files processed by the AzureQueue engine.
It is safe to truncate or drop this table at any time.
system.background_schedule_pool_log	System table containing history of background schedule pool task executions.
system.background_schedule_pool	System table containing information about tasks in background schedule pools.
system.backup_log	System table containing logging entries with information about BACKUP and RESTORE operations.
system.backups	System table containing logging entries with information about BACKUP and RESTORE operations.
system.blob_storage_log	System table containing logging entries with information about various blob storage operations such as uploads and deletes.
system.build_options	System table containing information about ClickHouse server’s build options.
system.certificates	Contains information about available certificates and their sources.
system.clusters	System table containing information about clusters available in the config file and the servers defined in them.
system.codecs	System table containing information about codecs in queue.
system.collations	Contains a list of all available collations for alphabetical comparison of strings.
system.columns	System table containing information about columns in all tables
system.completions	Contains a list of completion tokens.
system.contributors	System table containing information about contributors.
system.crash_log	System table containing information about stack traces for fatal errors.
system.current_roles	System table containing active roles for the current user.
system.dashboards	Contains queries used by /dashboard page accessible though the HTTP interface. useful for monitoring and troubleshooting.
system.data_skipping_indices	System table containing information about existing data skipping indices in all the tables.
system.data_skipping_index_types	System table containing a list of data skipping index types supported by the server along with their embedded documentation.
system.data_type_families	System table containing information about supported data types
system.database_engines	System table containing a list of database engines supported by the server.
system.database_replicas	System table containing information about and status of replicated database.
system.databases	System table containing information about the databases that are available to the current user.
system.dead_letter_queue	System table containing information about messages received via a streaming engine and parsed with errors.
system.delta_lake_metadata_log	System table containing information about metadata files read from Delta Lake tables. Each entry represents a root metadata JSON file.
system.detached_parts	System table containing information about detached parts of MergeTree tables
system.detached_tables	System table containing information about each detached table.
system.dictionaries	System table containing information about dictionaries
system.dictionary_sources	System table containing a list of dictionary sources supported by the server along with their embedded documentation.
system.dictionary_layouts	System table containing a list of dictionary layouts supported by the server along with their embedded documentation.
system.dimensional_metrics	This table contains dimensional metrics that can be calculated instantly and exported in the Prometheus format. It is always up to date.
system.disk_types	System table containing a list of disk types supported by the server along with their embedded documentation.
system.disks	System table containing information about disks defined in the server configuration
system.distributed_ddl_queue	System table containing information about distributed ddl queries (queries using the ON CLUSTER clause) that were executed on a cluster.
system.distribution_queue	System table containing information about local files that are in the queue to be sent to the shards.
system.dns_cache	System table containing information about cached DNS records.
system.documentation	System table that collects the embedded documentation of the uniform components of the system (functions, table engines, data types, and so on) into a single table, with the reference documentation rendered as Markdown.
system.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
system.dropped_tables_parts	System table containing information about parts of MergeTree dropped tables from system.dropped_tables
system.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
system.error_log	System table containing the history of error values from table system.errors, periodically flushed to disk.
system.errors	System table containing error codes with the number of times they have been triggered.
system.events	System table containing information about the number of events that have occurred in the system.
system.fail_points	Contains a list of all available failpoints with their type and current status.
system.filesystem_cache_settings	Contains information about all filesystem cache settings
system.filesystem_read_prefetches_log	Contains a history of all prefetches done during reading from MergeTree tables backed by a remote filesystem.
It is safe to truncate or drop this table at any time.
system.filesystem_cache_log	Contains a history of all events occurred with filesystem cache for objects on a remote filesystem.
It is safe to truncate or drop this table at any time.
system.filesystem_cache	Contains information about all entries inside filesystem cache for remote objects.
system.formats	Contains a list of all the formats along with flags whether a format is suitable for input/output or whether it supports parallelization.
system.functions	System table containing information about normal and aggregate functions.
system.grants	System table showing which privileges are granted to ClickHouse user accounts.
system.graphite_retentions	System table containing information about parameters graphite_rollup which are used in tables with GraphiteMergeTree type engines.
system.histogram_metrics	This table contains histogram metrics that can be calculated instantly and exported in the Prometheus format. It is always up to date.
system.iceberg_history	System iceberg snapshot history
system.iceberg_files	System table containing per-file metadata of Iceberg tables
system.iceberg_metadata_log	System table containing information about metadata files read from Iceberg tables. Each entry represents either a root metadata file, metadata extracted from an Avro file, or an entry of some Avro file.
system.instrumentation	System table containing the instrumentation points
system.jemalloc_stats	Returns jemalloc statistics in a single row with a single column. Equivalent to SYSTEM JEMALLOC STATS command.
system.jemalloc_bins	System table containing information about memory allocations done via jemalloc allocator in different size classes (bins) aggregated from all arenas.
system.jemalloc_profile_text	Displays the symbolized jemalloc heap profile. Run ‘SYSTEM JEMALLOC FLUSH PROFILE’ to generate a profile first.
system.kafka_consumers	System table containing information about Kafka consumers.
system.keeper_cluster	System table which exists only when this node runs an in-process ClickHouse Keeper. Contains one row per Raft cluster member as seen by this Keeper.
system.keeper_snapshots	System table which exists only when this node runs an in-process ClickHouse Keeper. Contains one row per on-disk Raft snapshot tracked by the Keeper state machine.
system.keeper_changelogs	System table which exists only when this node runs an in-process ClickHouse Keeper. Contains one row per on-disk Raft changelog file tracked by the Keeper log store.
system.keywords	Contains a list of all keywords used in ClickHouse parser.
system.licenses	System table containing licenses of third-party libraries that are located in the contrib directory of ClickHouse sources.
system.macros	Contains a list of all macros defined in server configuration.
system.masking_policies	System table containing information about all masking policies in the system.
system.merge_tree_settings	System table containing information about settings for MergeTree tables.
system.merges	System table containing information about merges and part mutations currently in process for tables in the MergeTree family.
system.metric_log	System table containing history of metrics values from tables system.metrics and system.events, periodically flushed to disk.
system.metrics	System table containing metrics which can be calculated instantly, or have a current value.
system.models	Contains a list of CatBoost models loaded into a LibraryBridge’s memory along with time when it was loaded.
system.moves	System table containing information about in-progress data part moves of MergeTree tables. Each data part movement is represented by a single row.
system.mutations	System table containing information about mutations of MergeTree tables and their progress. Each mutation command is represented by a single row.
system.named_collections	Содержит список всех именованных коллекций, созданных с помощью SQL-запроса или разобранных из файла конфигурации.
system.numbers_mt	Системная таблица, аналогичная system.numbers, но чтение в ней распараллелено, и числа могут возвращаться в любом порядке.
system.numbers	Системная таблица, содержащая один столбец UInt64 с именем number, в котором содержатся почти все натуральные числа, начиная с нуля.
system.one	Системная таблица, содержащая одну строку с одним столбцом UInt8 dummy, содержащим значение 0. Аналогична таблице DUAL, встречающейся в других СУБД.
system.opentelemetry_span_log	Системная таблица, содержащая информацию о спанах трассировки для выполненных запросов.
system.part_moves_between_shards	Содержит информацию о частях, которые в данный момент перемещаются между сегментами, и о ходе этого процесса.
system.part_log	Системная таблица, содержащая информацию о событиях, произошедших с частями данных в таблицах семейства MergeTree, таких как добавление данных или слияние.
system.parts	Системная таблица, содержащая информацию о частях таблиц MergeTree
system.parts_columns	Системная таблица, содержащая информацию о частях и столбцах таблиц MergeTree.
system.predicate_statistics_log	Системная таблица, содержащая выборочную статистику селективности фильтров и индексов, собранную из конвейеров чтения MergeTree во время выполнения запросов.
system.primes	Системная таблица, содержащая единственный столбец UInt64 с именем prime, в котором хранятся простые числа в порядке возрастания, начиная с 2.
system.privileges	Содержит список всех доступных привилегий, которые могут быть предоставлены пользователю или роли.
system.processes	Системная таблица, используемая для реализации запроса SHOW PROCESSLIST.
system.processors_profile_log	Системная таблица, содержащая информацию профилирования на уровне processors (её можно найти в EXPLAIN PIPELINE)
system.projection_parts_columns	Системная таблица, содержащая информацию о столбцах в частях проекций для таблиц семейства MergeTree
system.projection_parts	Системная таблица, содержащая информацию о частях проекций для таблиц семейства MergeTree.
system.projections	Системная таблица, содержащая информацию о существующих проекциях во всех таблицах.
system.query_views_log	Системная таблица, содержащая информацию о зависимых представлениях, выполняемых при запуске запроса, например об их типе или времени выполнения.
system.query_condition_cache	Системная таблица, показывающая содержимое кэша условий запроса.
system.query_thread_log	Системная таблица, содержащая информацию о потоках, выполняющих запросы, например имя потока, время его запуска и длительность обработки запроса.
system.query_metric_log	Системная таблица, содержащая историю значений памяти и метрик из таблицы system.events для отдельных запросов, периодически сбрасываемую на диск.
system.query_log	Системная таблица, содержащая информацию о выполненных запросах, например время начала, длительность обработки и сообщения об ошибках.
system.query_cache	Системная таблица, показывающая содержимое кэша запросов.
system.quota_usage	Системная таблица, содержащая информацию об использовании квот текущим пользователем, например какая часть квоты использована и сколько осталось.
system.quota_limits	Системная таблица, содержащая информацию о максимумах для всех интервалов всех квот. Одной квоте может соответствовать любое количество строк или ни одной.
system.quotas_usage	Системная таблица, содержащая информацию об использовании квот всеми пользователями.
system.quotas	Системная таблица, содержащая информацию о квотах.
system.remote_data_paths	Системная таблица, содержащая информацию о файлах данных, хранящихся на удалённых дисках, таких как S3 или Azure Blob Storage.
system.replicas	Системная таблица, содержащая информацию о реплицированных таблицах, расположенных на локальном сервере, и их состоянии. Полезна для мониторинга.
system.replicated_merge_tree_settings	Содержит список всех настроек, специфичных для движка ReplicatedMergeTree, их текущих значений и значений по умолчанию, а также описания. Вы можете изменить любую из них в разделе SETTINGS запроса CREATE.
system.replicated_fetches	System table containing information about currently running background fetches.
system.replication_queue	System table containing information about tasks from replication queues stored in ClickHouse Keeper, or ZooKeeper, for tables in the ReplicatedMergeTree family.
system.resources	System table containing information about resources residing on the local server with one row for every resource.
system.rocksdb	Contains a list of metrics exposed from embedded RocksDB.
system.role_grants	System table containing the role grants for users and roles.
system.roles	System table containing information about configured roles.
system.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.
system.s3_queue_settings	System table containing information about the settings of S3Queue tables. Available from server version 24.10.
system.s3queue_metadata_cache	Contains in-memory state of S3Queue metadata and currently processed rows per file.
system.s3queue_log	Contains log entries with information about files processed by the S3Queue engine.
It is safe to truncate or drop this table at any time.
system.scheduler	System table containing information about and status of scheduling nodes residing on the local server.
system.schema_inference_cache	System table containing information about all cached file schemas.
system.server_settings	System table containing formation about global settings for the server, which are specified in config.xml.
system.session_log	System table containing information about all successful and failed login and logout events.
system.settings	System table containing information about session settings for current user.
system.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.
system.settings_changes	System table containing information about setting changes in previous ClickHouse versions.
system.settings_profiles	System table which contains properties of configured setting profiles.
system.stack_trace	System table which contains stack traces of all server threads. Allows developers to introspect the server state.
system.storage_policies	System table containing information about storage policies and volumes which are defined in server configuration.
system.symbols	System table useful for C++ experts and ClickHouse engineers containing information for introspection of the clickhouse binary.
system.table_engines	System table containing descriptions of table engines supported by the server and the features they support.
system.table_functions	Contains a list of all available table functions with their descriptions.
system.tables	System table containing metadata of each table that the server knows about.
system.text_log	System table containing logging entries.
system.time_zones	System table containing a list of time zones that are supported by the ClickHouse server.
system.tokenizers	System table which shows all available tokenizers.
system.trace_log	System table containing stack traces collected by the sampling query profiler.
system.transactions	Contains a list of transactions and their state.
system.transactions_info_log	Contains information about all transactions executed on a current server.
It is safe to truncate or drop this table at any time.
system.unicode	System table containing a list of Unicode characters and their properties.
system.user_processes	System table containing information useful for an overview of memory usage and ProfileEvents of users.
system.user_directories	Contains the information about configured user directories - directories on the file system from which ClickHouse server is allowed to read user provided data.
system.user_defined_functions	System table containing loading status and configuration metadata for User-Defined Functions (UDFs).
system.users	System table containing a list of user accounts configured on the server.
system.view_refreshes	System table containing information about Refreshable Materialized Views.
system.warnings	This table contains warning messages about clickhouse server.
system.warnings	Contains warnings about server configuration to be displayed by clickhouse-client right after it connects to the server.
system.workloads	System table containing information for workloads residing on the local server.
system.zeros	Produces unlimited number of non-materialized zeros.
system.zeros_mt	Multithreaded version of system.zeros.
system.zookeeper_watches	System table showing currently active ZooKeeper watches registered by this ClickHouse server.
system.zookeeper_info	System table which outputs introspection of all available keeper nodes.
system.zookeeper_log	System table containing information about the parameters of the request to the ZooKeeper server and the response from it.
system.zookeeper_connection	System table which exists only if ZooKeeper is configured. Shows current connections to ZooKeeper (including auxiliary ZooKeepers).
system.zookeeper_connection_log	Shows the history of ZooKeeper connections (including auxiliary ZooKeepers).
system.zookeeper	System table which exists only if ClickHouse Keeper or ZooKeeper are configured. It exposes data from the Keeper cluster defined in the config.