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From "Lars Volker (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-4167: Support insert plan hints for CREATE TABLE AS SELECT
Date Mon, 08 Jan 2018 14:04:10 GMT
Lars Volker has posted comments on this change. ( )

Change subject: IMPALA-4167: Support insert plan hints for CREATE TABLE AS SELECT

Patch Set 6:


Apologies for the delayed review. I had a few more questions. Let's discuss the parser changes
in person if you feel I misunderstood the approach.
Commit Message:
PS6, Line 19: more
add "more memory efficient"? That makes it more obvious why it is more efficient to do additional
work (sorting).
PS6, Line 27: Add exchange node before insert even in case of unpartitioned tables.
I don't think this is true, is it? For unpartitioned tables, what would the shuffle / exchange
do? Instead "shuffle" forces an exchange, "noshuffle" prevents adding one, and leaving it
out results in the planner making a cost-based decision (
PS6, Line 35: was moved from tbl_def_without_col_defs to statement rules.
Mention how you tested it in the commit message.
File fe/src/main/cup/sql-parser.cup:
PS6, Line 1055: plan_hints:hints
Does opt_plan_hints not work here?
File fe/src/main/java/org/apache/impala/analysis/
PS6, Line 69:    * Helper class for parsing.
Is this class still needed or a left-over from earlier patch-sets? Can you expand the class
comment to explain why we need it and what it does?
File fe/src/test/java/org/apache/impala/analysis/
PS6, Line 1701: Multiple non-conflicting
Can you add one that has multiple distinct hints, like shuffle, clustered?
File testdata/workloads/functional-planner/queries/PlannerTest/ddl.test:
PS6, Line 233: shuffle
Is that true? Without specifying a hint there should be cases where the cost based heuristic
decides against adding an exchange node.
At first I didn't understand what this one does (I saw that insert.test:574 has the same).
On my machine this exchange collects all rows at the coordinator. Maybe you want to add that
in a comment?

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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I8d74bca999da8ae1bb89427c70841f33e3c56ab0
Gerrit-Change-Number: 8400
Gerrit-PatchSet: 6
Gerrit-Owner: Csaba Ringhofer <>
Gerrit-Reviewer: Csaba Ringhofer <>
Gerrit-Reviewer: Gabor Kaszab <>
Gerrit-Reviewer: Lars Volker <>
Gerrit-Comment-Date: Mon, 08 Jan 2018 14:04:10 +0000
Gerrit-HasComments: Yes

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