Oracle Database Tips by Donald Burleson

The schema OUTLN owns the package OUTLN_PKG that is used to manage stored outlines and their outline categories. The database administrator should change the password for the OUTLN schema just as for the SYS and SYSTEM schemas. OUTLINEs are not available in the STANDARD release of Oracle only in the ENTERPRISE release.

The "c0800050.sql" upgrade script from 8.0.5 to 8.1.x also creates the schema OUTLN.

The package outln_pkg is created by script "dbmsol.sql" in the  $ORACLE_HOME/rdbms/admin directory. The "dbmsol.sql" script is called from  "catproc.sql". The file "prvtol.plb" creates the body of "outln_pkg"; it is also called from catproc.

There are other tables (base tables), indexes, grants, and synonyms related to this package created during the install process by the SQL.BSQ script. 

After carefully tuning an application, you might want to ensure that the optimizer generates the same execution plan whenever the same SQL statements  are executed. This is accomplished via OUTLINEs. OUTLINEs can be generated in either the rule or cost based optimizer. Plan stability allows you to maintain the same execution plans for the same SQL statements, regardless of changes to the database such as re-analyzing tables, adding or deleting data, modifying a table's columns, constraints, or indexes, changing the system configuration, or even upgrading to a new version of the optimizer. 

The CREATE OUTLINE statement creates a stored outline, which contains a set of attributes that the optimizer uses to create an execution plan. Stored outlines can also be created automatically by setting the system parameter CREATE_STORED_OUTLINES to TRUE. 

The system parameter USE_STORED_OUTLINES can be set to TRUE, FALSE, or a  category name to indicate whether to make use of existing stored outlines for queries that are being executed. The OUTLN_PKG package provides procedures used for managing stored outlines.