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executor: refineArgs() bug fix when compare int with very small decimal #23694

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merged 3 commits into from
Mar 30, 2021
Merged

executor: refineArgs() bug fix when compare int with very small decimal #23694

merged 3 commits into from
Mar 30, 2021

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guo-shaoge
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@guo-shaoge guo-shaoge commented Mar 30, 2021 •
edited by XuHuaiyu
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Signed-off-by: guo-shaoge shaoge1994@163.com

What problem does this PR solve?

Issue Number:
close #23623
close #23684

Problem Summary: In the following case, output of select stmt should be 2, but current result is 3.

Why: c1 is nullable, so we cannot assuse all value in c1 will be greater than the result of subquery, which is less than int32_min. Because result of null > xxx is NULL

drop table if exists t1;
create table t1(c1 int);
insert into t1 values(-2147483648), (-2147483648), (null);
select count(*) from t1 where c1 > (select sum(c1) from t1);

What is changed and how it works?

What's Changed: when refineArgs(), should check if column is nullable. If is nullable, we should not try to optimize compare expression.

Related changes

  • Need to cherry-pick to the release branch

Check List

Tests

  • Integration test

Side effects

  • Performance regression
    • Consumes more CPU: may cause performance regression compared when compare int_column with const if int_column is nullable.

Release note

  • fix bug when compare int_column with constant value

@guo-shaoge
executor: refineArgs() bug fix when compare int with very small decimal
f31bf4e 
Signed-off-by: guo-shaoge <shaoge1994@163.com>
@guo-shaoge
fix case
f2154b3 
Signed-off-by: guo-shaoge <shaoge1994@163.com>
@guo-shaoge
Merge branch 'master' of https://github.com/pingcap/tidb into issue-2…
a2d8a15 
…3623_refine_arg_bug

Signed-off-by: guo-shaoge <shaoge1994@163.com>
@guo-shaoge guo-shaoge requested a review from a team as a code owner March 30, 2021 10:52
@guo-shaoge guo-shaoge requested review from wshwsh12 and removed request for a team March 30, 2021 10:52
@ti-chi-bot ti-chi-bot added the size/S Denotes a PR that changes 10-29 lines, ignoring generated files. label Mar 30, 2021
@zz-jason zz-jason added the priority/release-blocker This issue blocks a release. Please solve it ASAP. label Mar 30, 2021
XuHuaiyu
XuHuaiyu reviewed Mar 30, 2021
View reviewed changes
expression/builtin_compare.go Outdated
// Why check not null flag
// eg: int_col > const_val(which is less than min_int32)
// If int_col got null, compare result cannot be true
if arg0IsInt && !arg0IsCon && !arg1IsInt && arg1IsCon && mysql.HasNotNullFlag(arg0Type.Flag) {
arg1, isExceptional = RefineComparedConstant(ctx, *arg0Type, arg1, c.op)
finalArg1 = arg1
if isExceptional && arg1.GetType().EvalType() == types.ETInt {
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If arg1 == false, can we ignore the not-null flag ?

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@guo-shaoge guo-shaoge Mar 30, 2021 •
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select xxx where (col_int > (select sum(xx) xx) ) is null;

So need to distinguish null or false of GT expr.

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CI needs to be fixed.

@ichn-hu ichn-hu mentioned this pull request Mar 30, 2021
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@guo-shaoge guo-shaoge requested a review from a team as a code owner March 30, 2021 12:23
@guo-shaoge guo-shaoge requested review from eurekaka and removed request for a team March 30, 2021 12:23
@ti-chi-bot ti-chi-bot added size/M Denotes a PR that changes 30-99 lines, ignoring generated files. and removed size/S Denotes a PR that changes 10-29 lines, ignoring generated files. labels Mar 30, 2021
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/run-all-tests

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/run-all-tests

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/lgtm

@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Mar 30, 2021
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[REVIEW NOTIFICATION]

This pull request has been approved by:

  • XuHuaiyu
  • lzmhhh123

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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@ti-chi-bot ti-chi-bot added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Mar 30, 2021
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/merge

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This pull request has been accepted and is ready to merge.

Commit hash: a2d8a15

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Mar 30, 2021
@ti-chi-bot ti-chi-bot merged commit 3ed4a23 into pingcap:master Mar 30, 2021
ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 30, 2021
@guo-shaoge @ti-srebot
cherry pick pingcap#23694 to release-4.0
131c784 
Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
@ti-srebot ti-srebot mentioned this pull request Mar 30, 2021
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cherry pick to release-4.0 in PR #23705

ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 30, 2021
@guo-shaoge @ti-srebot
cherry pick pingcap#23694 to release-5.0
241cec9 
Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
@ti-srebot ti-srebot mentioned this pull request Mar 30, 2021
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cherry pick to release-5.0 in PR #23706

@guo-shaoge guo-shaoge deleted the issue-23623_refine_arg_bug branch March 30, 2021 15:01
ti-chi-bot pushed a commit that referenced this pull request Mar 31, 2021
@ti-srebot
executor: refineArgs() bug fix when compare int with very small decim…
d114bb4 
…al (#23694) (#23706)
ti-chi-bot pushed a commit that referenced this pull request May 10, 2021
@ti-srebot
executor: refineArgs() bug fix when compare int with very small decim…
b118f70 
…al (#23694) (#23705)
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@XuHuaiyu XuHuaiyu XuHuaiyu left review comments

@lzmhhh123 lzmhhh123 lzmhhh123 approved these changes

@wshwsh12 wshwsh12 Awaiting requested review from wshwsh12

@eurekaka eurekaka Awaiting requested review from eurekaka

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executor: wrong results from subquery wrong result when including subquery
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