xvi
Parallel DML Tips..................................................................................................................... 21-87
Incremental Data Loading in Parallel.................................................................................... 21-90
Using Hints with Cost-Based Optimization ......................................................................... 21-92
FIRST_ROWS(n) Hint .............................................................................................................. 21-93
Enabling Dynamic Statistic Sampling.................................................................................... 21-93
22 Query Rewrite
Overview of Query Rewrite............................................................................................................ 22-2
Cost-Based Rewrite..................................................................................................................... 22-3
When Does Oracle Rewrite a Query? ...................................................................................... 22-4
Enabling Query Rewrite.................................................................................................................. 22-7
Initialization Parameters for Query Rewrite .......................................................................... 22-8
Controlling Query Rewrite........................................................................................................ 22-8
Privileges for Enabling Query Rewrite.................................................................................... 22-9
Accuracy of Query Rewrite..................................................................................................... 22-10
How Oracle Rewrites Queries...................................................................................................... 22-11
Text Match Rewrite Methods.................................................................................................. 22-12
General Query Rewrite Methods............................................................................................ 22-13
When are Constraints and Dimensions Needed?................................................................ 22-14
Special Cases for Query Rewrite ................................................................................................. 22-45
Query Rewrite Using Partially Stale Materialized Views................................................... 22-45
Query Rewrite Using Complex Materialized Views........................................................... 22-49
Query Rewrite Using Nested Materialized Views............................................................... 22-50
Query Rewrite When Using GROUP BY Extensions .......................................................... 22-51
Did Query Rewrite Occur?............................................................................................................ 22-56
Explain Plan............................................................................................................................... 22-56
DBMS_MVIEW.EXPLAIN_REWRITE Procedure ............................................................... 22-57
Design Considerations for Improving Query Rewrite Capabilities..................................... 22-63
Query Rewrite Considerations: Constraints......................................................................... 22-63
Query Rewrite Considerations: Dimensions........................................................................ 22-63
Query Rewrite Considerations: Outer Joins ......................................................................... 22-63
Query Rewrite Considerations: Text Match ......................................................................... 22-63
Query Rewrite Considerations: Aggregates......................................................................... 22-64
Query Rewrite Considerations: Grouping Conditions ....................................................... 22-64
Query Rewrite Considerations: Expression Matching........................................................ 22-64