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From "Alex Behm (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4303: Do not reset() qualifier of union operands.
Date Thu, 01 Dec 2016 06:56:53 GMT
Alex Behm has posted comments on this change.

Change subject: IMPALA-4303: Do not reset() qualifier of union operands.
......................................................................


Patch Set 1:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/4963/1/fe/src/main/java/org/apache/impala/analysis/UnionStmt.java
File fe/src/main/java/org/apache/impala/analysis/UnionStmt.java:

Line 56:    * Contains a query statement and the all/distinct qualifier
> adapt or remove that last sentence, which is redundant anyway.
Done


Line 61:     // distinct propagation and unnesting that are needed after rewriting Subqueries.
> i don't understand the semantics of UnionStmt.reset() anymore. if we're try
Your summary seems correct to me. UnionStmt.reset() undoes all analysis state, except unnesting
and distinct propagation.

There is no need to preserve distinctOperands_ and allOperands_ because operands_ also contains
those after analysis.

A saner version of reset() would of course undo all changes made in analyze(). Unfortunately,
that is rather difficult because analyze() does in-place modifications to the operands and
even nested operands_ lists during unnesting, and also overwrites the original operands_.

Added comment to reset().


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Gerrit-MessageType: comment
Gerrit-Change-Id: I157bb0f08c4a94fd779487d7c23edd64a537a1f6
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Marcel Kornacker <marcel@cloudera.com>
Gerrit-HasComments: Yes

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