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planner: fix stack overflow caused by folding constant#10174

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qw4990 merged 6 commits intopingcap:masterfrom
qw4990:fix_10156
Apr 18, 2019
Merged

planner: fix stack overflow caused by folding constant#10174
qw4990 merged 6 commits intopingcap:masterfrom
qw4990:fix_10156

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@qw4990 qw4990 commented Apr 16, 2019

What problem does this PR solve?

Fix #10156.

What is changed and how it works?

When creating dummy function in foldConstant, use NewFunctionBase to avoid it fold it again.

Check List

Tests

  • Unit test

@qw4990 qw4990 added type/bugfix This PR fixes a bug. sig/planner SIG: Planner labels Apr 16, 2019
@qw4990 qw4990 requested review from alivxxx, eurekaka and winoros April 16, 2019 13:13
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codecov bot commented Apr 16, 2019 •
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Codecov Report

Merging #10174 into master will decrease coverage by 0.061%.
The diff coverage is 8%.

@@               Coverage Diff                @@
##             master     #10174        +/-   ##
================================================
- Coverage   77.9754%   77.9143%   -0.0611%     
================================================
  Files           407        405         -2     
  Lines         82635      82343       -292     
================================================
- Hits          64435      64157       -278     
- Misses        13424      13441        +17     
+ Partials       4776       4745        -31

shenli
shenli reviewed Apr 16, 2019
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Do we need to cherry-pick this to the release-2.1 branch?

Comment thread sessionctx/stmtctx/stmtctx.go
alivxxx
alivxxx reviewed Apr 17, 2019
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LGTM

@alivxxx alivxxx added the status/LGT1 Indicates that a PR has LGTM 1. label Apr 17, 2019
winoros
winoros reviewed Apr 17, 2019
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Why in #10156 , you said we can use ConstItem to fix it, but here just replace NewFunctionInternal by NewFunctionBase?

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qw4990 commented Apr 17, 2019

Why in #10156 , you said we can use ConstItem to fix it, but here just replace NewFunctionInternal by NewFunctionBase?

Because CorrelatedColumn.ConstItem() always returns true now, it's not correct.
In fact, we have to differentiate between planner-stage and execution-stage for it.

In planner-stage, for example when building scalar function, it should return false because its result depend on column data.
In execution-stage, for example when building range in some operators, since the outer row has been chosen, we can regard it as a const.

I will fix this problem in another PR.
So for this problem, I fix it by the way for simplicity.

@qw4990 qw4990 requested a review from zz-jason April 18, 2019 05:41
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qw4990 commented Apr 18, 2019

PTAL~

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LGTM

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zz-jason commented Apr 18, 2019

This bug is introduced in #7696
@qw4990 Please cherry pick this fix to the release 2.1 branch

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zz-jason commented Apr 18, 2019

/run-all-tests

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qw4990 commented Apr 18, 2019

/run-unit-test

@qw4990 qw4990 merged commit e13181f into pingcap:master Apr 18, 2019
qw4990 added a commit to qw4990/tidb that referenced this pull request Apr 18, 2019
@qw4990
planner: fix stack overflow caused by folding constant (pingcap#10174)
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@qw4990 qw4990 mentioned this pull request Apr 18, 2019
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@zz-jason zz-jason zz-jason approved these changes

@eurekaka eurekaka Awaiting requested review from eurekaka

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Stack overflow caused by checking constant wrongly

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