sridhar bamandlapally, 27.01.2012 05:31:
SQL> explain plan for select * from hr.emp ; Explained. PLAN -------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 7444K| 944M| 16077 (4)| 00:03:13 | | 1 | TABLE ACCESS FULL| EMP | 7444K| 944M| 16077 (4)| 00:03:13 | -------------------------------------------------------------------------- *WITH PARALLEL Option* SQL> explain plan for select /*+parallel(emp,4)*/ * from hr.emp ; Explained. PLAN --------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 7444K| 944M| 4442 (3)| 00:00:54 | | 1 | PX COORDINATOR | | | | | | | 2 | PX SEND QC (RANDOM)| :TQ10000 | 7444K| 944M| 4442 (3)| 00:00:54 | | 3 | PX BLOCK ITERATOR | | 7444K| 944M| 4442 (3)| 00:00:54 | | 4 | TABLE ACCESS FULL| EMP | 7444K| 944M| 4442 (3)| 00:00:54 | --------------------------------------------------------------------------------- In the above plan ( WITH PARALLEL Option ) 1. "Cost" has been nearly reduced to 1/4th 2. "CPU" has been reduced 3. "Time" has been nearly reduced to 1/3rd
I have *never* seen the "time" column in the explain plan output come anywhere near the actual execution time in Oracle. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
