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From "Marcel Kornacker (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-1286: Extract common conjuncts from disjunctions.
Date Sat, 29 Oct 2016 02:43:27 GMT
Marcel Kornacker has posted comments on this change.

Change subject: IMPALA-1286: Extract common conjuncts from disjunctions.
......................................................................


Patch Set 1:

(3 comments)

http://gerrit.cloudera.org:8080/#/c/4877/1/fe/src/main/java/org/apache/impala/rewrite/ExtractCommonConjunctRule.java
File fe/src/main/java/org/apache/impala/rewrite/ExtractCommonConjunctRule.java:

Line 37: public class ExtractCommonConjunctRule implements ExprRewriteRule {
where is this being applied?


http://gerrit.cloudera.org:8080/#/c/4877/1/testdata/workloads/functional-planner/queries/PlannerTest/tpch-all.test
File testdata/workloads/functional-planner/queries/PlannerTest/tpch-all.test:

Line 3384:       p_brand = 'Brand#12'
> I'm not really sure how this patch handles a bushy predicate. Do we flatten
i agree, i think we need normalization as a separate transformation step. this will be a prerequisite
for other transformations as well, and having to bake normalization into every single transformation
rule doesn't make sense.


Line 3393:       p_brand = 'Brand#23'
additional idea for transformation rule: derive additional, non-essential disjunctive scan
predicates if the selectivity of the base predicates is sufficiently small (for '=', say).

in the example: brand = 12 or brand = 23 or brand = 34 as an extra scan predicate for 'parts',
if 'brand' has a sufficiently high cardinality.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I3cf9b950afaa3fd753d1b09ba5e540b5258940ad
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Bharath Vissapragada <bharathv@cloudera.com>
Gerrit-Reviewer: Marcel Kornacker <marcel@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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