Wrong Parallel Query Result
Last updated on FEBRUARY 02, 2017
Applies to:Oracle Server - Enterprise Edition - Version 220.127.116.11 to 18.104.22.168 [Release 11.1 to 11.2]
Information in this document applies to any platform.
A query without any hints returns 919,312 rows. However, when a parallel hint is added, the query returns a lesser number of rows. Serial execution returns the correct number of rows.
When setting these hidden parameters, then wrong numbers are reporting as well:
alter session set "_optimizer_eliminate_filtering_join"=false; -- 200824 rows
alter session set "_bloom_filter_enabled" = false; -- 114930 rows
Basically, the parallel statement might return wrong results when joining views containing
order by or group by on the join columns.
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