Never seen this line in an execution plan before
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Date: Wed, 12 Aug 2020 23:03:25 +0000
Message-ID: <BY5PR08MB6294E4CCE98DA1D8EDD9A512FE420_at_BY5PR08MB6294.namprd08.prod.outlook.com>
A fellow DBA asked me to take a look at this. He had increased the number of hash partitions in a table in our performance testing environment. The plan changed and performance got much, much worse (all in cpu usage).
Date: Wed, 12 Aug 2020 23:03:25 +0000
Message-ID: <BY5PR08MB6294E4CCE98DA1D8EDD9A512FE420_at_BY5PR08MB6294.namprd08.prod.outlook.com>
A fellow DBA asked me to take a look at this. He had increased the number of hash partitions in a table in our performance testing environment. The plan changed and performance got much, much worse (all in cpu usage).
What is weird is that the only thing in the plan that changed was the line PARTITION REFERENCE ITERATOR became PARTITION REFERENCE AND. I’ve never heard of PARTITION REFERENCE AND. Googling and searching Metalink did not produce any hits. We have a ticket open with Oracle but they aren’t answering the question of what the significance is of that difference so I thought I’d throw it out to the collective wisdom of the freelisters. Anyone know what this line means?
Oracle 12.2.0.1
RH Linux 6.10
Here are the old and new plans:
Pred Op Par. #Sib Query Block ms spent in Consistent Rowsource Real #rows Est. rows Opt. Card. Current Physical Physical Memory Workarea Optimizer
#Col ID ID ling Row Source name this operation gets starts returned total misestimate gets read blks write blks used (MB) Passes Cost
----- ----- ----- ----- ------------------------------------------------------------------------ -------------------- -------------- ---------- ---------- ----------- ------------- --------------- ---------- ---------- ---------- ------------- ------------- ----------- 0 SELECT STATEMENT >>> Plan totals >>> 202 F 1 0 1 FILTER SEL$1 2 1 1 INLIST ITERATOR 3 2 1 PARTITION REFERENCE ITERATOR 202 4 3 1 TABLE ACCESS BY LOCAL INDEX ROWID BATCHED [ORDER_ACTIVITY] SEL$1 202 A#1 5 4 1 INDEX RANGE SCAN [ORDER_STRATEGY_ORDER_ACTIVI_FK] SEL$1 58 6 1 2 SORT AGGREGATE SEL$2 7 6 1 PARTITION REFERENCE SINGLE 7 F 8 7 1 TABLE ACCESS BY LOCAL INDEX ROWID BATCHED [ORDER_ACTIVITY] SEL$2 7 A#1 9 8 1 INDEX RANGE SCAN [ORDER_STRATEGY_ORDER_ACTIVI_FK] SEL$2 4 Pred Op Par. #Sib Query Block ms spent in Consistent Rowsource Real #rows Est. rows Opt. Card. Current Physical Physical Memory Workarea Optimizer
#Col ID ID ling Row Source name this operation gets starts returned total misestimate gets read blks write blks used (MB) Passes Cost
----- ----- ----- ----- ------------------------------------------------------------------------ -------------------- -------------- ---------- ---------- ----------- ------------- --------------- ---------- ---------- ---------- ------------- ------------- ----------- 0 SELECT STATEMENT >>> Plan totals >>> 364 F 1 0 1 FILTER SEL$1 2 1 1 INLIST ITERATOR 3 2 1 PARTITION REFERENCE AND 364 4 3 1 TABLE ACCESS BY LOCAL INDEX ROWID BATCHED [ORDER_ACTIVITY] SEL$1 364 A#1 5 4 1 INDEX RANGE SCAN [ORDER_STRATEGY_ORDER_ACTIVI_FK] SEL$1 103 6 1 2 SORT AGGREGATE SEL$2 7 6 1 PARTITION REFERENCE SINGLE 7 F 8 7 1 TABLE ACCESS BY LOCAL INDEX ROWID BATCHED [ORDER_ACTIVITY] SEL$2 7 A#1 9 8 1 INDEX RANGE SCAN [ORDER_STRATEGY_ORDER_ACTIVI_FK] SEL$2 4
Predicate information and outline hints are identical between the 2 plans.
Thank you!
Jay Miller
-- http://www.freelists.org/webpage/oracle-lReceived on Thu Aug 13 2020 - 01:03:25 CEST