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From "Mostafa Mokhtar (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4787: Optimize APPX MEDIAN() memory usage
Date Sun, 19 Feb 2017 04:51:09 GMT
Mostafa Mokhtar has posted comments on this change.

Change subject: IMPALA-4787: Optimize APPX_MEDIAN() memory usage
......................................................................


Patch Set 2:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/6025/2/be/src/exprs/aggregate-functions-ir.cc
File be/src/exprs/aggregate-functions-ir.cc:

PS2, Line 1024: new_size 
> 2x works for me but:
With 10x adding a couple of more rows to the table the memory requirements for a query can
go from 3GB to 30GB, which might not be acceptable. 
Hash table used for joins behave similarly, they start small and double in size as need be.

If the goal is to improve performance of APPEX_MEDIAN then we should be looking at more than
just the memory curve.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I99adaad574d4fb0a3cf38c6cbad8b2a23df12968
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Taras Bobrovytsky <tbobrovytsky@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Jim Apple <jbapple-impala@apache.org>
Gerrit-Reviewer: Marcel Kornacker <marcel@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Mostafa Mokhtar <mmokhtar@cloudera.com>
Gerrit-Reviewer: Taras Bobrovytsky <tbobrovytsky@cloudera.com>
Gerrit-HasComments: Yes

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