[jira] [Created] (HIVE-6614) Vectorized aggregates computed on map side diffe (hash mode) from values computed on reduce side (streaming mode)

["Remus Rusanu (JIRA)" <ji...@apache.org>]

Remus Rusanu created HIVE-6614:
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             Summary: Vectorized aggregates computed on map side diffe (hash mode) from values computed on reduce side (streaming mode)
                 Key: HIVE-6614
                 URL: https://issues.apache.org/jira/browse/HIVE-6614
             Project: Hive
          Issue Type: Bug
            Reporter: Remus Rusanu
            Assignee: Remus Rusanu
            Priority: Critical


HIVE-6222 allows vectorized aggregates to operate on streaming mode, ie. flush after each key change and let the shuffle+reduce side to compute the final aggregate values. An error in patch .2 for HIVE-6222 shows that when the queries run in streaming mode, there are rounding diffs for some agg functions (VAR and friends). These occurred for non-decimal types, like ctinyint:

{code}
select csmallint, VAR_POP(ctinyint) from alltypesorc where csmallint = -75 group by csmallint;
{code}

This produces  107.55555555555556 vs. 107.55555555555554.






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