Re: 9.2 - Parallel Query Not Working
- From: "Greg Rahn" <greg@xxxxxxxxxxxxxxxxxx>
- To: tony.adolph.dba@xxxxxxxxx
- Date: Thu, 27 Mar 2008 15:03:02 -0700
On Thu, Mar 27, 2008 at 1:51 PM, Tony Adolph <tony.adolph.dba@xxxxxxxxx> wrote:
> You'll only get parallel table access for full table scans, .i.e. the
> table is not accessed via index lookup.
If you are saying that only FTS run in parallel, and not index access,
that is not a correct statement. Index access can be parallelized.
Here is a execution plan where the table is accessed via index lookup
(rowids gotten from the index scan). Both the index and table access
are parallel.
SELECT * FROM FACT_TABLE
WHERE KEY_FACT_ID>=69329730003700001 AND
KEY_FACT_ID"<=69329730003700010
-----------------------------------------------------------------------------------------
| Id | Operation | Name | TQ
|IN-OUT| PQ Distrib |
-----------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | |
| |
| 1 | PX COORDINATOR | | |
| |
| 2 | PX SEND QC (RANDOM) | :TQ10000 | Q1,00 |
P->S | QC (RAND) |
| 3 | PX PARTITION HASH ALL | | Q1,00 |
PCWC | |
| 4 | TABLE ACCESS BY LOCAL INDEX ROWID| FACT_TABLE | Q1,00 |
PCWP | |
| 5 | INDEX RANGE SCAN | FACT_PK | Q1,00 |
PCWP | |
-----------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
5 - access("KEY_FACT_ID">=69329730003700001 AND
"KEY_FACT_ID"<=69329730003700010)
--
Regards,
Greg Rahn
http://structureddata.org
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