expression: use the correct type when eval decimal and float session var #51395

Rustin170506 · 2024-02-28T08:55:54Z

What problem does this PR solve?

Issue Number: close #43527

Problem Summary:

What changed and how does it work?

create table test (a datetime, b bigint, c decimal(10, 2), d float);
insert into test values('2010-10-10 10:10:10', 100, 100.01, 100);
SELECT @total := @total + c FROM (SELECT c FROM test) AS temp, (SELECT @total := 200) AS T1;

In the SQL, @total type is int64, but when we do eval decimal we will directly convert it as decimal then we will get a panic because there is no x for int value.
GetMysqlDecimal:

func (d *Datum) GetMysqlDecimal() *MyDecimal {
	return d.x.(*MyDecimal)
}

ToDecimal:

func (d *Datum) ToDecimal(ctx Context) (*MyDecimal, error) {
	switch d.Kind() {
	case KindMysqlTime:
		return d.GetMysqlTime().ToNumber(), nil
	case KindMysqlDuration:
		return d.GetMysqlDuration().ToNumber(), nil
	default:
		return ConvertDatumToDecimal(ctx, *d)
	}
}

So we have to try to convert it explicitly.

Same for the float value eval process. We also need to convert it.

Because #8412 disabled the vectorized execution of get or set variable, so we don't really execute that code right now. But I also updated it.

Check List

Tests

Unit test
Integration test
Manual test (add detailed scripts or steps below)
No need to test
- I checked and no code files have been changed.

Side effects

Performance regression: Consumes more CPU
Performance regression: Consumes more Memory
Breaking backward compatibility

Documentation

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

Fixed an issue that TiDB could not correctly convert the type of a session variable
修复 TiDB 无法正确转换表达式中系统变量类型的问题

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

Rustin170506

🔢 Self-check

cc: @time-and-fate

Thanks for your help!

Rustin170506 · 2024-02-28T09:16:58Z

/retest

codecov · 2024-02-28T09:19:21Z

Codecov Report

Merging #51395 (a3484a5) into master (c23f0c9) will increase coverage by 2.4235%.
Report is 23 commits behind head on master.
The diff coverage is 20.0000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #51395        +/-   ##
================================================
+ Coverage   70.6663%   73.0898%   +2.4235%     
================================================
  Files          1461       1462         +1     
  Lines        434876     442198      +7322     
================================================
+ Hits         307311     323202     +15891     
+ Misses       108307      99059      -9248     
- Partials      19258      19937       +679

Flag	Coverage Δ
integration	`49.3792% <20.0000%> (?)`
unit	`70.6050% <20.0000%> (+0.1424%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	`53.9957% <ø> (ø)`
parser	`∅ <ø> (∅)`
br	`51.2558% <ø> (+5.3537%)`	⬆️

Rustin170506 · 2024-02-28T09:38:49Z

/retest

elsa0520

LGTM

XuHuaiyu · 2024-02-29T02:16:34Z

pkg/expression/builtin_other.go

@@ -1052,7 +1052,11 @@ func (b *builtinGetRealVarSig) evalReal(ctx EvalContext, row chunk.Row) (float64
 	}
 	varName = strings.ToLower(varName)
 	if v, ok := sessionVars.GetUserVarVal(varName); ok {
-		return v.GetFloat64(), false, nil


What about the implementation of (b *builtinGetRealVarSig) vecEvalReal

Because this PR: #8412

There is no way to vectorized eval real. But I guess it makes sense to update it as well.

Yes, please. Much appreciated.

Let's talk about enabling vectorization for get/set var function in the future.

zanmato1984

Is there any case we can add into this UT:

tidb/pkg/expression/builtin_other_test.go

Line 118 in 27ce02a

func TestGetVar(t *testing.T) {

.
As well as https://github.com/pingcap/tidb/blob/27ce02afd2e3d312b2bb92e20489cefce000e320/pkg/expression/builtin_other_vec_test.go , assuming you are going to add vectorized version of builtinGetRealVarSig.

zanmato1984 · 2024-02-29T03:38:03Z

pkg/expression/builtin_other.go

@@ -1052,7 +1052,11 @@ func (b *builtinGetRealVarSig) evalReal(ctx EvalContext, row chunk.Row) (float64
 	}
 	varName = strings.ToLower(varName)
 	if v, ok := sessionVars.GetUserVarVal(varName); ok {
-		return v.GetFloat64(), false, nil


Signed-off-by: hi-rustin <rustin.liu@gmail.com>

Rustin170506

🔢 Self-check

zanmato1984

LGTM

elsa0520

LGTM

ti-chi-bot · 2024-02-29T09:34:22Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, elsa0520, zanmato1984

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ti-chi-bot · 2024-02-29T09:34:26Z

[LGTM Timeline notifier]

Timeline:

2024-02-28 09:20:18.283019794 +0000 UTC m=+1040107.030642913: ☑️ agreed by AilinKid.
2024-02-28 10:00:50.671372065 +0000 UTC m=+1042539.418995171: ☑️ agreed by elsa0520.
2024-02-29 03:41:45.72004397 +0000 UTC m=+1106194.467667080: ✖️🔁 reset by zanmato1984.
2024-02-29 09:18:32.645908407 +0000 UTC m=+1126401.393531518: ☑️ agreed by zanmato1984.
2024-02-29 09:34:25.804268372 +0000 UTC m=+1127354.551891483: ☑️ agreed by elsa0520.

ti-chi-bot · 2024-05-21T00:09:19Z

In response to a cherrypick label: new pull request created to branch release-7.5: #53415.

Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>

…var (#51395) (#53415) close #43527

Rustin170506 added 2 commits February 28, 2024 16:30

expression: use the correct type when eval decimal system var

d7d734b

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

expression: use the correct type when eval float system var

c73ae0a

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

ti-chi-bot bot added do-not-merge/needs-triage-completed release-note Denotes a PR that will be considered when it comes time to generate release notes. size/S Denotes a PR that changes 10-29 lines, ignoring generated files. labels Feb 28, 2024

Rustin170506 changed the title ~~expression: use the correct type when eval decimal system var~~ expression: use the correct type when eval decimal and float session var Feb 28, 2024

ti-chi-bot bot removed the do-not-merge/needs-triage-completed label Feb 28, 2024

Rustin170506 added sig/planner SIG: Planner component/expression labels Feb 28, 2024

fix: build

fa83014

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

ti-chi-bot 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 Feb 28, 2024

Rustin170506 commented Feb 28, 2024

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Rustin170506 requested review from AilinKid and elsa0520 February 28, 2024 09:02

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fix: vec and add more tests

a3484a5

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

Rustin170506 commented Feb 29, 2024

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zanmato1984 approved these changes Feb 29, 2024

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ti-chi-bot bot merged commit 38ab23b into pingcap:master Feb 29, 2024
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ti-chi-bot added the needs-cherry-pick-release-7.5 Should cherry pick this PR to release-7.5 branch. label May 21, 2024

ti-chi-bot pushed a commit to ti-chi-bot/tidb that referenced this pull request May 21, 2024

This is an automated cherry-pick of pingcap#51395

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Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>

ti-chi-bot mentioned this pull request May 21, 2024

expression: use the correct type when eval decimal and float session var (#51395) #53415

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expression: use the correct type when eval decimal and float session …

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…var (#51395) (#53415) close #43527

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expression: use the correct type when eval decimal and float session var #51395

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Rustin170506 commented Feb 28, 2024 • edited Loading

What problem does this PR solve?

What changed and how does it work?

Check List

Release note

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[LGTM Timeline notifier]

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