Overview
INFORMATION_SCHEMA provides access to system metadata, such as the name of a database or table, the data type of a column, etc. GreptimeDB also provides some custom INFORMATION_SCHEMA tables to query metadata about the GreptimeDB system itself, cluster information, and runtime telemetry for example.
Many INFORMATION_SCHEMA tables have a corresponding SHOW command. The benefit of querying INFORMATION_SCHEMA is that it is possible to join between tables.
There is still lots of work to do for INFORMATION_SCHEMA. The tracking issue for INFORMATION_SCHEMA.
Tables for MySQL compatibility
| Table Name | Description |
|---|---|
CHARACTER_SETS | provides information about available character sets. |
CHECK_CONSTRAINTS | Not implemented. Returns zero rows. |
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. Returns zero rows. |
COLUMN_STATISTICS | Not supported. |
ENGINES | Provides a list of supported storage engines. |
EVENTS | Not implemented. Returns zero rows. |
FILES | Not implemented. Returns zero rows. |
GLOBAL_STATUS | Not implemented. Returns zero rows. |
GLOBAL_VARIABLES | Not supported. |
KEY_COLUMN_USAGE | Describes the key constraints of the columns, such as the primary key, and time index constraint. |
OPTIMIZER_TRACE | Not implemented. Returns zero rows. |
PARAMETERS | Not implemented. Returns zero rows. |
PARTITIONS | Provides a list of table partitions. |
PLUGINS | Not supported. |
PROCESSLIST | Not supported. |
PROFILING | Not implemented. Returns zero rows. |
REFERENTIAL_CONSTRAINTS | Not implemented. Returns zero rows. |
ROUTINES | Not implemented. Returns zero rows. |
SCHEMATA | Provides similar information to SHOW DATABASES. |
SCHEMA_PRIVILEGES | Not implemented. Returns zero rows. |
SESSION_STATUS | Not implemented. Returns zero rows. |
SESSION_VARIABLES | Not supported. |
STATISTICS | Not supported. |
TABLES | Provides a list of tables that the current user has visibility of. Similar to SHOW TABLES. |
TABLESPACES | Not supported. |
TABLE_PRIVILEGES | Not implemented. Returns zero rows. |
TRIGGERS | Not implemented. Returns zero rows. |
USER_ATTRIBUTES | Not supported. |
USER_PRIVILEGES | Not supported. |
VARIABLES_INFO | Not supported. |
VIEWS | Not supported. |
Tables that GreptimeDB provides
| Table Name | Description |
|---|---|
BUILD_INFO | Provides the system build info. |
GREPTIME_REGION_PEERS | Provides details about where regions are stored. |
RUNTIME_METRICS | Provides the system runtime metrics. |