Information Schema
Information Schema provides an ANSI-standard way of viewing system metadata. TiDB also provides a number of custom INFORMATION_SCHEMA tables, in addition to the tables included for MySQL compatibility.
Many INFORMATION_SCHEMA tables have a corresponding SHOW command. The benefit of querying INFORMATION_SCHEMA is that it is possible to join between tables.
Tables for MySQL compatibility
| Table Name | Description |
|---|---|
CHARACTER_SETS | Provides a list of character sets the server supports. |
CHECK_CONSTRAINTS | Provides information about CHECK constraints on tables. |
COLLATIONS | Provides a list of collations that the server supports. |
COLLATION_CHARACTER_SET_APPLICABILITY | Explains which collations apply to which character sets. |
COLUMNS | Provides a list of columns for all tables. |
COLUMN_PRIVILEGES | Not implemented by TiDB. Returns zero rows. |
COLUMN_STATISTICS | Not implemented by TiDB. Returns zero rows. |
ENGINES | Provides a list of supported storage engines. |
EVENTS | Not implemented by TiDB. Returns zero rows. |
FILES | Not implemented by TiDB. Returns zero rows. |
GLOBAL_STATUS | Not implemented by TiDB. Returns zero rows. |
GLOBAL_VARIABLES | Not implemented by TiDB. Returns zero rows. |
KEYWORDS | Provides a full list of keywords. |
KEY_COLUMN_USAGE | Describes the key constraints of the columns, such as the primary key constraint. |
OPTIMIZER_TRACE | Not implemented by TiDB. Returns zero rows. |
PARAMETERS | Not implemented by TiDB. Returns zero rows. |
PARTITIONS | Provides a list of table partitions. |
PLUGINS | Not implemented by TiDB. Returns zero rows. |
PROCESSLIST | Provides similar information to the command SHOW PROCESSLIST. |
PROFILING | Not implemented by TiDB. Returns zero rows. |
REFERENTIAL_CONSTRAINTS | Provides information on FOREIGN KEY constraints. |
ROUTINES | Not implemented by TiDB. Returns zero rows. |
SCHEMATA | Provides similar information to SHOW DATABASES. |
SCHEMA_PRIVILEGES | Not implemented by TiDB. Returns zero rows. |
SESSION_STATUS | Not implemented by TiDB. Returns zero rows. |
SESSION_VARIABLES | Provides similar functionality to the command SHOW SESSION VARIABLES |
STATISTICS | Provides information on table indexes. |
TABLES | Provides a list of tables that the current user has visibility of. Similar to SHOW TABLES. |
TABLESPACES | Not implemented by TiDB. Returns zero rows. |
TABLE_CONSTRAINTS | Provides information on primary keys, unique indexes and foreign keys. |
TABLE_PRIVILEGES | Not implemented by TiDB. Returns zero rows. |
TRIGGERS | Not implemented by TiDB. Returns zero rows. |
USER_ATTRIBUTES | Summarizes information about user comments and user attributes. |
USER_PRIVILEGES | Summarizes the privileges associated with the current user. |
VARIABLES_INFO | Provides information about TiDB system variables. |
VIEWS | Provides a list of views that the current user has visibility of. Similar to running SHOW FULL TABLES WHERE table_type = 'VIEW' |
Tables that are TiDB extensions
| Table Name | Description |
|---|---|
ANALYZE_STATUS | Provides information about tasks to collect statistics. |
CLIENT_ERRORS_SUMMARY_BY_HOST | Provides a summary of errors and warnings generated by client requests and returned to clients. |
CLIENT_ERRORS_SUMMARY_BY_USER | Provides a summary of errors and warnings generated by clients. |
CLIENT_ERRORS_SUMMARY_GLOBAL | Provides a summary of errors and warnings generated by clients. |
CLUSTER_CONFIG | Provides details about configuration settings for the entire TiDB cluster. This table is not applicable to TiDB Cloud. |
CLUSTER_DEADLOCKS | Provides a cluster-level view of the DEADLOCKS table. |
CLUSTER_HARDWARE | Provides details on the underlying physical hardware discovered on each TiDB component. This table is not applicable to TiDB Cloud. |
CLUSTER_INFO | Provides details on the current cluster topology. This table is not available on TiDB Cloud Serverless clusters. |
CLUSTER_LOAD | Provides current load information for TiDB servers in the cluster. This table is not applicable to TiDB Cloud. |
CLUSTER_LOG | Provides a log for the entire TiDB cluster. This table is not applicable to TiDB Cloud. |
CLUSTER_MEMORY_USAGE | Provides a cluster-level view of the MEMORY_USAGE table. |
CLUSTER_MEMORY_USAGE_OPS_HISTORY | Provides a cluster-level view of the MEMORY_USAGE_OPS_HISTORY table. |
CLUSTER_PROCESSLIST | Provides a cluster-level view of the PROCESSLIST table. |
CLUSTER_SLOW_QUERY | Provides a cluster-level view of the SLOW_QUERY table. This table is not available on TiDB Serverless clusters. |
CLUSTER_STATEMENTS_SUMMARY | Provides a cluster-level view of the STATEMENTS_SUMMARY table. This table is not available on TiDB Serverless clusters. |
CLUSTER_STATEMENTS_SUMMARY_HISTORY | Provides a cluster-level view of the STATEMENTS_SUMMARY_HISTORY table. This table is not available on TiDB Serverless clusters. |
CLUSTER_TIDB_TRX | Provides a cluster-level view of the TIDB_TRX table. |
CLUSTER_SYSTEMINFO | Provides details about kernel parameter configuration for servers in the cluster. This table is not applicable to TiDB Cloud. |
DATA_LOCK_WAITS | Provides the lock-waiting information on the TiKV server. |
DDL_JOBS | Provides similar output to ADMIN SHOW DDL JOBS |
DEADLOCKS | Provides the information of several deadlock errors that have recently occurred. |
INSPECTION_RESULT | Triggers internal diagnostics checks. This table is not applicable to TiDB Cloud. |
INSPECTION_RULES | A list of internal diagnostic checks performed. This table is not applicable to TiDB Cloud. |
INSPECTION_SUMMARY | A summarized report of important monitoring metrics. This table is not applicable to TiDB Cloud. |
MEMORY_USAGE | The memory usage of the current TiDB instance. |
MEMORY_USAGE_OPS_HISTORY | The history of memory-related operations and the execution basis of the current TiDB instance. |
METRICS_SUMMARY | A summary of metrics extracted from Prometheus. This table is not applicable to TiDB Cloud. |
METRICS_SUMMARY_BY_LABEL | See METRICS_SUMMARY table. This table is not applicable to TiDB Cloud. |
METRICS_TABLES | Provides the PromQL definitions for tables in METRICS_SCHEMA. This table is not applicable to TiDB Cloud. |
PLACEMENT_POLICIES | Provides information on all placement policies. This table is not available on TiDB Cloud Serverless clusters. |
SEQUENCES | The TiDB implementation of sequences is based on MariaDB. |
SLOW_QUERY | Provides information on slow queries on the current TiDB server. This table is not available on TiDB Cloud Serverless clusters. |
STATEMENTS_SUMMARY | Similar to performance_schema statement summary in MySQL. This table is not available on TiDB Cloud Serverless clusters. |
STATEMENTS_SUMMARY_HISTORY | Similar to performance_schema statement summary history in MySQL. This table is not available on TiDB Cloud Serverless clusters. |
TABLE_STORAGE_STATS | Provides details about table sizes in storage. |
TIDB_HOT_REGIONS | Provides statistics about which regions are hot. |
TIDB_HOT_REGIONS_HISTORY | Provides history statistics about which Regions are hot. |
TIDB_INDEXES | Provides index information about TiDB tables. |
TIDB_SERVERS_INFO | Provides a list of TiDB servers (namely, tidb-server component) |
TIDB_TRX | Provides the information of the transactions that are being executed on the TiDB node. |
TIFLASH_REPLICA | Provides details about TiFlash replicas. |
TIKV_REGION_PEERS | Provides details about where regions are stored. |
TIKV_REGION_STATUS | Provides statistics about regions. |
TIKV_STORE_STATUS | Provides basic information about TiKV servers. |