MySQL 9.5 Reference Manual Including MySQL NDB Cluster 9.5
      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.