IT Database Administration Section 04

The Oracle 9i Data Dictionary  A set of tables and views owned by SYS and accessible using SQL  Can be queried in identical fashion to user tables  Base tables have names like tab$, obj$, etc

The Oracle 9i Data Dictionary  The Data Dictionary contains  Usernames and their rights and privileges  Information on space allocation and usage  Details of database structure  Auditing information  Relational table structure and contents  Special monitoring and performance tables  Full details of all stored (server-side) code

The Oracle 9i Data Dictionary  The Data Dictionary should never be directly updated using SQL  Should be changed only using DDL statements  The Oracle Data Dictionary grows each release

Data Dictionary Construction  The base dictionary tables are built during database creation  Difficult to read and direct use of them is unsupported  Change in structure each release

Data Dictionary Construction  The views are built by running the scripts catalog and catproc  Catalog builds views that refer to nonprocedural objects  Example: user_tables  Catproc builds the views to support procedural objects  Example: user_triggers

Data Dictionary Construction  Many additional supplied scripts can be used to extend the dictionary support for more specialized activity  Found in Oracle_Home\rdbms\admin folder

Standard Types of Dictionary Views  user_% views  Refer to the user’s own environment and give concise information  Return a subset of the all_% views  Some have additional alternative public synonyms for ease of use

Standard Types of Dictionary Views  all_% views  Refer to the user’s own environment and resources, plus show details of objects to which they have access

Standard Types of Dictionary Views  dba_% views  Accessible only to DBAs or users granted Oracle Catalog roles

The Dynamic Performance Views (v$ views)  Used by DBAs to monitor performance  Owned by SYS  Built on the x$ dictionary base tables  Names begin with v_$  Some useful views:  v$parameterv$sga  v$sqlv$sqltext  v$sessionv$filestat  v$rowcachev$rollstat

Questions?