RDBMS store their meta-data (like name of tables, column data-types etc) in:
- System database
- System schema
- Catalog
- Directory
You can query the metadata tables to discover information about the objects in db
Different RDBMS use different names for their metadata store:
- DB2 uses:
1. catalog : Information about Tables and Permissions
2. directory : Information about Control data, Recovery data
- MySQL uses: Have read-only tables in each schema
1. Information_Schema :
2. MySQL:
3. Performance_Schema:
4. sys:
- PostgreSQL uses
1. System Catalog: Schema with tables and views about all other data in database
Other meta-data:
Configuration files: contains information of DBMS you specify during the DBMS
installation in (.conf, .nfg, .ini) extension files. They contain configuration
parameters like port number, connection time-out, memory allocation, maximum
packet size etc
- DB2 has SQLDBCONF file
- MySQL has my.ini, my.cnf files
- PostgreSQL has postgresql.conf file