Comments on: A gotcha with parallel index builds, parallel degree and query plans http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/?utm_source=rss&utm_medium=rss&utm_campaign=a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans Oracle, Exadata, Performance, Troubleshooting - Mobile Life and Productivity. Wed, 08 Feb 2012 08:03:50 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Sue W - DBA in Hawaii http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-7847 Sue W - DBA in Hawaii Wed, 03 Aug 2011 23:05:27 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-7847 be sure it's after the first command, e.g. CREATE /*+ parallel 3 */ TABLE/INDEX be sure it’s after the first command, e.g. CREATE /*+ parallel 3 */ TABLE/INDEX

]]> By: Sue W - DBA in Hawaii http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-7846 Sue W - DBA in Hawaii Wed, 03 Aug 2011 23:03:50 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-7846 Use of /*+ parallel */ will use parallel cpu engines without changing the object (parallel) degree value (as observed in dba_tables or dba_indexes). Use of /*+ parallel */ will use parallel cpu engines without changing the object (parallel) degree value (as observed in dba_tables or dba_indexes).

]]> By: oracle tom http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-6694 oracle tom Tue, 22 Mar 2011 07:53:15 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-6694 for my reorg / ilm job i just save all table and index parallel degrees to a table and reset them after the reorg job is done. for my reorg / ilm job i just save all table and index parallel degrees to a table and reset them after the reorg job is done.

]]> By: Index rebuilds in parallel change the parallel DEGREE « DBA n00b http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-3979 Index rebuilds in parallel change the parallel DEGREE « DBA n00b Thu, 04 Mar 2010 20:11:59 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-3979 [...] 4, 2010 by tylerv As many of the comments to this handy article say, we got stung by this one today.  Definitely check out the article.  After a large data [...] [...] 4, 2010 by tylerv As many of the comments to this handy article say, we got stung by this one today.  Definitely check out the article.  After a large data [...]

]]> By: Parallel Reasoning « Charles Hooper's Oracle Notes http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-3868 Parallel Reasoning « Charles Hooper's Oracle Notes Wed, 17 Feb 2010 06:04:17 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-3868 [...] A Gotcha with Parallel Index Builds, Parallel Degree and Query Plans I haven’t enabled parallelism for my table! How can Oracle go parallel without my consent?  Parallel index (re)build will persistently set the index parallel degree in data dictionary to the value used during build! [...] [...] A Gotcha with Parallel Index Builds, Parallel Degree and Query Plans I haven’t enabled parallelism for my table! How can Oracle go parallel without my consent?  Parallel index (re)build will persistently set the index parallel degree in data dictionary to the value used during build! [...]

]]> By: Tanel Poder http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-1459 Tanel Poder Mon, 27 Apr 2009 19:23:26 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-1459 Did you gather optimizer stats on the table and index using dbms_stats? which command exactly did you use? Did you gather optimizer stats on the table and index using dbms_stats? which command exactly did you use?

]]> By: kwanyoung oh http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-1457 kwanyoung oh Mon, 27 Apr 2009 17:37:46 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-1457 Hi, I ran the scripts up there. But I found one strange thing in the execution plan. How come we have a lot different value in the Estimated rows and actual rows? SQL> set linesize 132 SQL> select /*+ gather_plan_statistics */ sum(object_id) from t1 where object_id > 60000; SUM(OBJECT_ID) -------------- 65869754 SQL> @x PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------------------------------------------------------ SQL_ID 6tk45guj3gkcg, child number 0 ------------------------------------- select /*+ gather_plan_statistics */ sum(object_id) from t1 where object_id > 60000 Plan hash value: 2596547647 ------------------------------------------------------------------------------------------------ | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | ------------------------------------------------------------------------------------------------ | 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.01 | 3 | | 2 | PX COORDINATOR | | 1 | | 4 |00:00:00.01 | 3 | PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------------------------------------------------------ | 3 | PX SEND QC (RANDOM) | :TQ10000 | 0 | 1 | 0 |00:00:00.01 | 0 | | 4 | SORT AGGREGATE | | 0 | 1 | 0 |00:00:00.01 | 0 | | 5 | PX BLOCK ITERATOR | | 0 | 19660 | 0 |00:00:00.01 | 0 | |* 6 | INDEX FAST FULL SCAN| I1 | 0 | 19660 | 0 |00:00:00.01 | 0 | ------------------------------------------------------------------------------------------------ Predicate Information (identified by operation id): --------------------------------------------------- 6 - access(:Z>=:Z AND :Z60000) PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------------------------------------------------------ 23 rows selected. Hi,

I ran the scripts up there.
But I found one strange thing in the execution plan.

How come we have a lot different value in the Estimated rows and actual rows?

SQL> set linesize 132
SQL> select /*+ gather_plan_statistics */ sum(object_id) from t1 where object_id > 60000;

SUM(OBJECT_ID)
————–
65869754

SQL> @x

PLAN_TABLE_OUTPUT
————————————————————————————————————————————
SQL_ID 6tk45guj3gkcg, child number 0
————————————-
select /*+ gather_plan_statistics */ sum(object_id) from t1 where object_id > 60000

Plan hash value: 2596547647

————————————————————————————————
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers |
————————————————————————————————
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.01 | 3 |
| 2 | PX COORDINATOR | | 1 | | 4 |00:00:00.01 | 3 |

PLAN_TABLE_OUTPUT
————————————————————————————————————————————
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 0 | 1 | 0 |00:00:00.01 | 0 |
| 4 | SORT AGGREGATE | | 0 | 1 | 0 |00:00:00.01 | 0 |
| 5 | PX BLOCK ITERATOR | | 0 | 19660 | 0 |00:00:00.01 | 0 |
|* 6 | INDEX FAST FULL SCAN| I1 | 0 | 19660 | 0 |00:00:00.01 | 0 |
————————————————————————————————

Predicate Information (identified by operation id):
—————————————————

6 – access(:Z>=:Z AND :Z60000)

PLAN_TABLE_OUTPUT
————————————————————————————————————————————

23 rows selected.

]]> By: Avi http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-79 Avi Tue, 16 Dec 2008 09:03:13 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-79 Hi, How value for DEFAULT is being calculated, can you please tell me? Hi,
How value for DEFAULT is being calculated, can you please tell me?

]]> By: Paul Leland http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-78 Paul Leland Mon, 25 Aug 2008 18:50:50 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-78 We seem to be hit by the same problem. Suddenly everything is ending with ORA-04031:Unable To allocate shared memory (“large pool”,”Unknown object”,”Large Pool”,”PX msg Pool”). We seem to be hit by the same problem. Suddenly everything is ending with ORA-04031:Unable To allocate shared memory (“large pool”,”Unknown object”,”Large Pool”,”PX msg Pool”).

]]> By: Paul Leland http://blog.tanelpoder.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/comment-page-1/#comment-77 Paul Leland Mon, 25 Aug 2008 18:50:02 +0000 http://tanelpoder.wordpress.com/2007/06/23/a-gotcha-with-parallel-index-builds-parallel-degree-and-query-plans/#comment-77 We seem to be hit by the same problem. Suddenly everything is ending with "Unable To allocate shared memory (“large pool”,”Unknown object”,”Large Pool”,”PX msg Pool”). We seem to be hit by the same problem. Suddenly everything is ending with “Unable To allocate shared memory (“large pool”,”Unknown object”,”Large Pool”,”PX msg Pool”).

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