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Database Objects (cont)

Consider what information the RDBMS needs about relations:
  • name, owner, primary key of each relation
  • name, data type, constraints for each attribute
  • authorisation for operations on each relation
Similarly for other DBMS objects (e.g. views, functions, triggers, ...)

This information is stored in the system catalog tables

Most DBMSs implement their own internal catalog structure

Standard for catalogs in SQL:2003: INFORMATION_SCHEMA

(implemented in PostgreSQL as a set of views on the catalog, Ch.34)