MySQL 8.4 Release Notes
28.3.32 INFORMATION_SCHEMA SCHEMATA_EXTENSIONS 表
The SCHEMATA_EXTENSIONS table augments the SCHEMATA table with information about schema options.
The SCHEMATA_EXTENSIONS table has these columns:
-
CATALOG_NAMEThe name of the catalog to which the schema belongs. This value is always
def. -
SCHEMA_NAMEThe name of the schema.
-
OPTIONSThe options for the schema. If the schema is read only, the value contains
READ ONLY=1. If the schema is not read only, noREAD ONLYoption appears.
mysql> ALTER SCHEMA mydb READ ONLY = 1;
mysql> SELECT * FROM INFORMATION_SCHEMA.SCHEMATA_EXTENSIONS
WHERE SCHEMA_NAME = 'mydb';
+--------------+-------------+-------------+
| CATALOG_NAME | SCHEMA_NAME | OPTIONS |
+--------------+-------------+-------------+
| def | mydb | READ ONLY=1 |
+--------------+-------------+-------------+
mysql> ALTER SCHEMA mydb READ ONLY = 0;
mysql> SELECT * FROM INFORMATION_SCHEMA.SCHEMATA_EXTENSIONS
WHERE SCHEMA_NAME = 'mydb';
+--------------+-------------+---------+
| CATALOG_NAME | SCHEMA_NAME | OPTIONS |
+--------------+-------------+---------+
| def | mydb | |
+--------------+-------------+---------+-
SCHEMATA_EXTENSIONSis a nonstandardINFORMATION_SCHEMAtable.