系统表

介绍什么是系统表及其用途。

页面	说明
System Tables Overview	Overview of what system tables are and why they are useful.
system.histogram_metric_log	System table containing periodic snapshots of histogram metrics, flushed to disk.
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_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.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.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.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	显示已向 ClickHouse 用户账户授予哪些权限的系统表。
system.graphite_retentions	包含参数 graphite_rollup 信息的系统表，这些参数用于使用 GraphiteMergeTree 类型引擎的表。
system.histogram_metrics	此表包含可即时计算并以 Prometheus 格式导出的直方图指标，且始终为最新数据。
system.iceberg_history	Iceberg 快照历史的系统表
system.iceberg_metadata_log	包含从 Iceberg 表读取的元数据文件信息的系统表。每个条目表示根元数据文件、从 Avro 文件中提取的元数据，或某个 Avro 文件中的一个条目。
system.instrumentation	包含插桩点信息的系统表
system.jemalloc_stats	以单行单列返回 jemalloc 统计信息。等同于 SYSTEM JEMALLOC STATS 命令。
system.jemalloc_bins	包含 jemalloc allocator 在不同大小类 (bins) 中的内存分配信息的系统表，这些信息聚合自所有 arena。
system.jemalloc_profile_text	显示已符号化的 jemalloc 堆内存剖析。请先运行 ‘SYSTEM JEMALLOC FLUSH PROFILE’ 生成 profile。
system.kafka_consumers	包含 Kafka 消费者信息的系统表。
system.keywords	包含 ClickHouse 解析器所使用的全部关键字列表。
system.licenses	包含位于 ClickHouse 源码 contrib 目录中的第三方库许可证信息的系统表。
system.macros	包含服务器配置中定义的所有宏列表。
system.masking_policies	包含系统中所有脱敏策略信息的系统表。
system.merge_tree_settings	包含 MergeTree 表设置相关信息的系统表。
system.merges	包含 MergeTree 家族中的表当前正在进行的合并和 part mutation 信息的系统表。
system.metric_log	包含表 system.metrics 和 system.events 中指标值历史记录的系统表，并会定期写入磁盘。
system.metrics	包含可即时计算或具有当前值的指标的系统表。
system.models	包含已加载到 LibraryBridge 内存中的 CatBoost 模型列表及其加载时间。
system.moves	包含 MergeTree 表中正在进行的数据分区片段移动信息的系统表。每次数据分区片段移动对应一行。
system.mutations	包含 MergeTree 表的变更及其进度信息的系统表。每条变更命令对应一行。
system.named_collections	包含所有通过 SQL 查询创建或从配置文件中解析出的 named collections 列表。
system.numbers_mt	与 system.numbers 类似的系统表，但读取是并行的，返回的数字顺序可能任意。
system.numbers	包含一个名为 number 的 UInt64 列的系统表，该列包含从零开始的几乎所有自然数。
system.one	包含单行且只有一个值为 0 的 dummy UInt8 列的系统表。类似于其他 DBMS 中的 DUAL 表。
system.opentelemetry_span_log	包含已执行查询的 trace span 信息的系统表。
system.part_moves_between_shards	包含当前正在分片之间移动的 parts 及其进度信息。
system.part_log	包含 MergeTree 家族中的表中与数据分区片段相关事件信息的系统表，例如数据的添加或合并。
system.parts	包含 MergeTree 的 parts 信息的系统表
system.parts_columns	包含 MergeTree 表的 parts 和列信息的系统表。
system.predicate_statistics_log	包含在查询执行期间从 MergeTree 读取管道中采样收集的过滤器和索引选择性统计信息的系统表。
system.primes	包含一个名为 prime 的 UInt64 列的系统表，该列按升序存储质数，从 2 开始。
system.privileges	包含可授予用户或角色的所有可用权限列表。
system.processes	用于实现 SHOW PROCESSLIST 查询的系统表。
system.processors_profile_log	包含处理器级别分析信息的系统表 (可在 EXPLAIN PIPELINE 中查看) 。
system.projection_parts_columns	包含 MergeTree 家族表中投影 parts 的列信息的系统表。
system.projection_parts	包含 MergeTree 家族表中投影 parts 信息的系统表。
system.projections	包含所有表中现有投影信息的系统表。
system.query_views_log	包含运行查询时所执行依赖视图信息的系统表，例如视图类型或执行时间。
system.query_condition_cache	显示查询条件缓存内容的系统表。
system.query_thread_log	包含执行查询的线程信息的系统表，例如线程名称、线程开始时间以及查询处理耗时。
system.query_metric_log	包含各个查询对应的 system.events 表中的内存和指标值历史记录的系统表，这些记录会定期写入磁盘。
system.query_log	包含已执行查询信息的系统表，例如开始时间、处理耗时和错误消息。
system.query_cache	显示查询缓存内容的系统表。
system.quota_usage	包含当前用户配额使用情况信息的系统表，例如已使用多少配额以及剩余多少。
system.quota_limits	包含所有 quotas 在各个时间区间内最大值信息的系统表。一个 quota 可以对应任意数量的行，也可以不对应任何行。
system.quotas_usage	包含所有用户配额使用情况信息的系统表。
system.quotas	包含 quotas 信息的系统表。
system.remote_data_paths	包含存储在远程磁盘 (如 S3 或 Azure Blob 存储) 上的数据文件信息的系统表。
system.replicas	包含本地服务器上复制表的信息和状态的系统表，可用于监控。
system.replicated_merge_tree_settings	包含所有 ReplicatedMergeTree 专有设置及其当前值、默认值和说明的列表。你可以在 CREATE 查询的 SETTINGS 部分更改其中任意一项。
system.replicated_fetches	包含当前正在运行的后台拉取操作信息的系统表。
system.replication_queue	包含 ReplicatedMergeTree 家族表在 ClickHouse Keeper 或 ZooKeeper 中存储的复制队列任务信息的系统表。
system.resources	包含本地服务器上资源信息的系统表，每个资源对应一行。
system.rocksdb	包含嵌入式 RocksDB 导出的指标列表。
system.role_grants	包含用户和角色的角色授权信息的系统表。
system.roles	包含已配置角色信息的系统表。
system.row_policies	包含某个特定表的过滤器，以及应使用此 ROW POLICY 的角色和/或用户列表的系统表。
system.s3_queue_settings	包含 S3Queue 表设置信息的系统表。自服务器版本 24.10 起可用。
system.s3queue_metadata_cache	包含 S3Queue 元数据的内存状态，以及每个文件当前正在处理的行。
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	包含有关服务器配置的警告，clickhouse-client 在连接到服务器后会立即显示这些警告。
system.workloads	包含本地服务器上 workloads 信息的系统表。
system.zeros	生成无限数量的非物化零值。
system.zeros_mt	system.zeros 的多线程版本。
system.zookeeper_watches	显示此 ClickHouse 服务器当前已注册且处于活动状态的 ZooKeeper watches 的系统表。
system.zookeeper_info	输出所有可用 Keeper 节点内部信息的系统表。
system.zookeeper_log	包含发送到 ZooKeeper 服务器的请求参数及其响应信息的系统表。
system.zookeeper_connection	仅在配置了 ZooKeeper 时存在的系统表。显示当前与 ZooKeeper 的连接 (包括辅助 ZooKeepers) 。
system.zookeeper_connection_log	显示 ZooKeeper 连接历史 (包括辅助 ZooKeepers) 。
system.zookeeper	仅在配置了 ClickHouse Keeper 或 ZooKeeper 时存在的系统表。它暴露配置中定义的 Keeper 集群中的数据。