planner: fix the row count for index join use the PK in inner side by Reminiscent · Pull Request #65190 · pingcap/tidb

Reminiscent · 2025-12-23T09:23:25Z

What problem does this PR solve?

Issue Number: close #65183

Problem Summary:
fix the row count for index join use the PK in inner side

What changed and how does it work?

Use the same way in the buildIndexJoinInner2IndexScan function(

tidb/pkg/planner/core/exhaust_physical_plans.go

Lines 918 to 927 in 0f706ff

    
           maxOneRow := false 
        
           if indexJoinResult.chosenPath.Index.Unique && indexJoinResult.usedColsLen == len(indexJoinResult.chosenPath.FullIdxCols) { 
        
           	l := len(indexJoinResult.chosenAccess) 
        
           	if l == 0 { 
        
           		maxOneRow = true 
        
           	} else { 
        
           		sf, ok := indexJoinResult.chosenAccess[l-1].(*expression.ScalarFunction) 
        
           		maxOneRow = ok && (sf.FuncName.L == ast.EQ) 
        
           	} 
        
           }

) which use to handle the unique index. It is very similar here. Check whether we use the full columns in the PK

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.

None

tiprow · 2025-12-23T09:23:47Z

Hi @Reminiscent. Thanks for your PR.

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Reminiscent · 2025-12-23T09:26:20Z

/ok-to-test

Reminiscent · 2025-12-23T09:29:00Z

@qw4990 @AilinKid PTAL

codecov · 2025-12-23T09:56:45Z

Codecov Report

❌ Patch coverage is 90.62500% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.6569%. Comparing base (4746c8d) to head (9cce572).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #65190        +/-   ##
================================================
- Coverage   77.8537%   77.6569%   -0.1968%     
================================================
  Files          1978       1902        -76     
  Lines        542181     529860     -12321     
================================================
- Hits         422108     411473     -10635     
+ Misses       118413     118381        -32     
+ Partials       1660          6      -1654

Flag	Coverage Δ
integration	`41.5483% <75.0000%> (-6.6416%)`	⬇️
unit	`76.7753% <90.6250%> (+0.3092%)`	⬆️

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

Components	Coverage Δ
dumpling	`56.7974% <ø> (ø)`
parser	`∅ <ø> (∅)`
br	`48.8378% <ø> (-12.2928%)`	⬇️

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Reminiscent · 2025-12-24T06:03:30Z

/retest-required

hawkingrei · 2026-01-04T03:03:33Z

/retest

qw4990 · 2026-01-13T08:01:39Z

pkg/planner/core/exhaust_physical_plans.go

+		maxOneRow := false
+		if indexJoinResult.chosenPath.Index.Unique && indexJoinResult.usedColsLen == len(indexJoinResult.chosenPath.FullIdxCols) {
+			l := len(indexJoinResult.chosenAccess)
+			if l == 0 {
+				maxOneRow = true
+			} else {
+				sf, ok := indexJoinResult.chosenAccess[l-1].(*expression.ScalarFunction)
+				maxOneRow = ok && (sf.FuncName.L == ast.EQ)
+			}
+		}


Could we wrap this part of code as a separate function? Then we can avoid some duplicated code.

AilinKid · 2026-01-14T05:41:30Z

pkg/planner/core/index_join_path.go

+	indexJoinResult *indexJoinPathResult) (rangeInfo string, maxOneRow bool) {
+	rangeInfo = indexJoinPathRangeInfo(sctx, outerJoinKeys, indexJoinResult)
+	maxOneRow = false
+	if indexJoinResult.chosenPath.Index.Unique && indexJoinResult.usedColsLen == len(indexJoinResult.chosenPath.FullIdxCols) {


AilinKid · 2026-01-14T05:42:55Z

/review

ti-chi-bot · 2026-01-14T05:42:58Z

[LGTM Timeline notifier]

Timeline:

2026-01-13 10:21:09.924639201 +0000 UTC m=+352913.986504113: ☑️ agreed by qw4990.
2026-01-14 05:42:57.324982429 +0000 UTC m=+422621.386847364: ☑️ agreed by AilinKid.

AilinKid · 2026-01-14T05:45:09Z

/retest-required

Reminiscent · 2026-01-14T09:06:38Z

/retest

ti-chi-bot · 2026-01-14T09:56:35Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, qw4990

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Reminiscent · 2026-01-15T01:39:37Z

/retest

hawkingrei · 2026-01-15T02:52:32Z

/retest

Reminiscent · 2026-01-15T03:56:10Z

/retest

Reminiscent · 2026-01-15T08:23:09Z

/retest

Reminiscent · 2026-01-15T09:51:12Z

/retest

ti-chi-bot · 2026-01-16T02:19:05Z

@Reminiscent: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-br-integration-test	`a3ed703`	link	true	`/test pull-br-integration-test`
pull-lightning-integration-test	`a3ed703`	link	true	`/test pull-lightning-integration-test`

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Reminiscent · 2026-01-16T02:58:02Z

/test mysql-test

tiprow · 2026-01-16T03:03:28Z

@Reminiscent: The specified target(s) for /test were not found.
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/test mysql-test

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…ingcap#65190) close pingcap#65183

Reminiscent · 2026-01-23T04:23:39Z

/cherrypick release-8.5

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

ti-chi-bot · 2026-01-23T04:24:28Z

@Reminiscent: new pull request created to branch release-8.5: #65745.
But this PR has conflicts, please resolve them!

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In response to this:

/cherrypick release-8.5

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ti-chi-bot bot added release-note-none Denotes a PR that doesn't merit a release note. do-not-merge/needs-tests-checked size/L Denotes a PR that changes 100-499 lines, ignoring generated files. sig/planner SIG: Planner and removed do-not-merge/needs-tests-checked labels Dec 23, 2025

ti-chi-bot bot added the ok-to-test Indicates a PR is ready to be tested. label Dec 23, 2025

Reminiscent marked this pull request as draft December 23, 2025 09:30

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Reminiscent marked this pull request as ready for review December 23, 2025 09:30

ti-chi-bot bot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Dec 23, 2025

qw4990 reviewed Jan 13, 2026

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ti-chi-bot bot added size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. and removed size/L Denotes a PR that changes 100-499 lines, ignoring generated files. labels Jan 14, 2026

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Reminiscent force-pushed the indexjoin_inner_row_size branch from a3ed703 to e60bf2e Compare January 14, 2026 09:56

ti-chi-bot bot added approved size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. labels Jan 14, 2026

Reminiscent force-pushed the indexjoin_inner_row_size branch from e60bf2e to 938a0db Compare January 14, 2026 09:58

ti-chi-bot bot added size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. and removed size/L Denotes a PR that changes 100-499 lines, ignoring generated files. labels Jan 15, 2026

Reminiscent added 5 commits January 16, 2026 10:14

planner: fix the row count for index join use the PK in inner side

4f28c40

remove the necessary change and update the comments

8da2395

address comments

6fcb11e

fix ut

639aad5

fix ut

9cce572

Reminiscent force-pushed the indexjoin_inner_row_size branch from c44d22c to 9cce572 Compare January 16, 2026 02:16

ti-chi-bot bot merged commit f8627fd into pingcap:master Jan 16, 2026
30 of 31 checks passed

Reminiscent deleted the indexjoin_inner_row_size branch January 16, 2026 03:36

hawkingrei pushed a commit to hawkingrei/tidb that referenced this pull request Jan 19, 2026

planner: fix the row count for index join use the PK in inner side (p…

9d1aeaa

…ingcap#65190) close pingcap#65183

ti-chi-bot pushed a commit to ti-chi-bot/tidb that referenced this pull request Jan 23, 2026

This is an automated cherry-pick of pingcap#65190

6b84d4c

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

ti-chi-bot mentioned this pull request Jan 23, 2026

planner: fix the row count for index join use the PK in inner side (#65190) #65745

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13 tasks

	maxOneRow := false
	if indexJoinResult.chosenPath.Index.Unique && indexJoinResult.usedColsLen == len(indexJoinResult.chosenPath.FullIdxCols) {
	l := len(indexJoinResult.chosenAccess)
	if l == 0 {
	maxOneRow = true
	} else {
	sf, ok := indexJoinResult.chosenAccess[l-1].(*expression.ScalarFunction)
	maxOneRow = ok && (sf.FuncName.L == ast.EQ)
	}
	}

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