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From "Tim Armstrong (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4864 Speed up single slot predicates with dictionaries
Date Tue, 06 Jun 2017 22:58:07 GMT
Tim Armstrong has posted comments on this change.

Change subject: IMPALA-4864 Speed up single slot predicates with dictionaries
......................................................................


Patch Set 16:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/6726/16/be/src/exec/parquet-column-readers.cc
File be/src/exec/parquet-column-readers.cc:

Line 420:               LIKELY(dictionary_results_.num_bits() > 0)) {
> Not liking this branch, but it is unavoidable without pre-computation overh
I think the predicate evaluation on 40,000 values is probably cheap enough to just do it.
In most cases we would have to evaluate the predicates anyway when processing the dictionary-encoded
pages.

I don't think I fully understand the inexpensive predicate check that you're envisioning.
Does it really need to be done per-row instead of per-batch (like the IS_DICT_ENCODED branch).


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Gerrit-MessageType: comment
Gerrit-Change-Id: I65981c89e5292086809ec1268f5a273f4c1fe054
Gerrit-PatchSet: 16
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Zach Amsden <zamsden@cloudera.com>
Gerrit-Reviewer: Joe McDonnell <joemcdonnell@cloudera.com>
Gerrit-Reviewer: Marcel Kornacker <marcel@cloudera.com>
Gerrit-Reviewer: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Zach Amsden <zamsden@cloudera.com>
Gerrit-HasComments: Yes

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