[HIVE-20285] Outer joins are underestimated

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Statistics
• Assignee: Unassigned
• Reporter: Zoltan Haindrich
• Created: 01/Aug/18 06:34
• Updated: 01/Aug/18 06:34

Description

It seems X LEFT OUTER JOIN Y is sometimes estimated to have fewer rows than X.

in ql/src/test/results/clientpositive/llap/auto_join29.q.out:

 SELECT * FROM src src1 LEFT OUTER JOIN src src2 ON (src1.key = src2.key AND src1.key < 10 AND src2.key 
> 10) LEFT OUTER JOIN src src3 ON (src2.key = src3.key AND src3.key < 10) SORT BY src1.key, src1.value, 
src2.key, src2.value, src3.key, src3.value