Wrong Parallel Query Result (Doc ID 1345433.1)

Last updated on FEBRUARY 02, 2017

Applies to:

Oracle Server - Enterprise Edition - Version 11.1.0.6 to 11.2.0.2 [Release 11.1 to 11.2]
Information in this document applies to any platform.

Symptoms

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.

Cause

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