MySQL 8.4 Reference Manual Including MySQL NDB Cluster 8.4
The SCHEMATA_EXTENSIONS table
augments the SCHEMATA table with
information about schema options.
The SCHEMATA_EXTENSIONS table has
these columns:
CATALOG_NAME
The name of the catalog to which the schema belongs. This
value is always def.
SCHEMA_NAME
The name of the schema.
OPTIONS
The options for the schema. If the schema is read only, the
value contains READ ONLY=1. If the schema
is not read only, no READ ONLY option
appears.
mysql>ALTER SCHEMA mydb READ ONLY = 1;mysql>SELECT * FROM INFORMATION_SCHEMA.SCHEMATA_EXTENSIONSWHERE 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_EXTENSIONSWHERE SCHEMA_NAME = 'mydb';+--------------+-------------+---------+ | CATALOG_NAME | SCHEMA_NAME | OPTIONS | +--------------+-------------+---------+ | def | mydb | | +--------------+-------------+---------+
SCHEMATA_EXTENSIONS is a
nonstandard INFORMATION_SCHEMA table.