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https://issues.apache.org/jira/browse/IMPALA-6590?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17765334#comment-17765334
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ASF subversion and git services commented on IMPALA-6590:
---------------------------------------------------------
Commit 130a55e5269ea023b43ef2c0b495989cb0759800 in impala's branch
refs/heads/master from Abhishek Rawat
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=130a55e52 ]
IMPALA-11284: Do non-optional rewrites for || and Between predicate
IMPALA-6590 disabled expression rewrites for ValuesStmt. However,
CompoundVerticalBarExpr (||) cannot be executed directly without
rewrite. This is because it could either be an OR operation with boolean
arguments or CONCAT function call with string arguments.
Backend cannot evaluate a BetweenPredicate and relies on rewriting
BetweenPredicate into a conjunctive or disjunctive CompoundPredicate.
This patch enables non-optional expression rewrites for ValuesStmt with
CompoundVerticalBarExpr or BetweenPredicate.
Testing:
- Extended ExprRewriterTest and Planner test to have values clause
with || and Between predicate
Change-Id: I99b8b33bf6468d12b9e26f0a6e744feb7072619c
Reviewed-on: http://gerrit.cloudera.org:8080/18581
Reviewed-by: Michael Smith <[email protected]>
Reviewed-by: Daniel Becker <[email protected]>
Tested-by: Riza Suminto <[email protected]>
> Disable expr rewrites and codegen for VALUES() statements
> ---------------------------------------------------------
>
> Key: IMPALA-6590
> URL: https://issues.apache.org/jira/browse/IMPALA-6590
> Project: IMPALA
> Issue Type: Bug
> Components: Frontend
> Affects Versions: Impala 2.8.0, Impala 2.9.0, Impala 2.10.0, Impala 2.11.0
> Reporter: Alexander Behm
> Assignee: Wenzhe Zhou
> Priority: Major
> Labels: perf, planner, ramp-up, regression
> Fix For: Impala 4.1.0
>
>
> The analysis of statements with big VALUES clauses like INSERT INTO <tbl>
> VALUES is slow due to expression rewrites like constant folding. The
> performance of such statements has regressed since the introduction of expr
> rewrites and constant folding in IMPALA-1788.
> We should skip expr rewrites for VALUES altogether since it mostly provides
> no benefit but can have a large overhead due to evaluation of expressions in
> the backend (constant folding). These expressions are ultimately evaluated
> and materialized in the backend anyway, so there's no point in folding them
> during analysis.
> Similarly, there is no point in doing codegen for these exprs in the backend
> union node.
> *Workaround*
> {code}
> SET ENABLE_EXPR_REWRITES=FALSE;
> SET DISABLE_CODEGEN=TRUE;
> {code}
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