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executor: fix wrong result of delete multiple tables using left join #33055

Merged
merged 8 commits into from
Mar 16, 2022
Merged

executor: fix wrong result of delete multiple tables using left join #33055

merged 8 commits into from
Mar 16, 2022

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guo-shaoge
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@guo-shaoge guo-shaoge commented Mar 14, 2022 •
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Signed-off-by: guo-shaoge shaoge1994@163.com

What problem does this PR solve?

Issue Number: close #31321

Problem Summary:
delete from t1, t2 using t1 left join t2 on t1.c1 = t2.c1;

row of t1: (1)
row of t2: (2)
The join result will be (1, null). 1 in t1 is matched, and no row in t2 is matched. So row in t1 should be deleted, while no row in t2 should be deleted.

But the original implementation didn't check if the row in t2 is matched or not, just delete it directly, which cause the wrong result.

What is changed and how it works?

If a row is not matched in outer join, the rowid of the join result will be NULL, we use this to decide if we can delete row.

Check List

Tests

  • Unit test
  • Integration test
  • Manual test (add detailed scripts or steps below)
  • No code

Side effects

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

Documentation

  • Affects user behaviors
  • Contains syntax changes
  • Contains variable changes
  • Contains experimental features
  • Changes MySQL compatibility

Release note

executor: fix wrong result of delete multiple tables using left join

@guo-shaoge
executor: fix wrong result of delete multiple tables using left join
d5f648f 
Signed-off-by: guo-shaoge <shaoge1994@163.com>
@guo-shaoge
fix case
e6809cc 
Signed-off-by: guo-shaoge <shaoge1994@163.com>
@guo-shaoge
fix comment
1835aad 
Signed-off-by: guo-shaoge <shaoge1994@163.com>
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ti-chi-bot commented Mar 14, 2022 •
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[REVIEW NOTIFICATION]

This pull request has been approved by:

  • winoros
  • wshwsh12

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@ti-chi-bot ti-chi-bot added release-note Denotes a PR that will be considered when it comes time to generate release notes. needs-cherry-pick-4.0 needs-cherry-pick-release-5.0 needs-cherry-pick-release-5.1 needs-cherry-pick-release-5.2 needs-cherry-pick-release-5.3 Type: Need cherry pick to release-5.3 needs-cherry-pick-release-5.4 Should cherry pick this PR to release-5.4 branch. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Mar 14, 2022
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/cc @wshwsh12

@guo-shaoge guo-shaoge requested a review from ekexium March 15, 2022 06:54
winoros
winoros reviewed Mar 15, 2022
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I just raise a question.

In the case you mentioned, the t2's columns are filled with NULL. How did we get its row id value so that unwanted deletion happened?

@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Mar 15, 2022
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guo-shaoge commented Mar 15, 2022 •
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I just raise a question.

In the case you mentioned, the t2's columns are filled with NULL. How did we get its row id value?

As we discussed, the rowid is NULL, but it's value is zero, So the row whose primary key is zero will be deleted.

wshwsh12
wshwsh12 approved these changes Mar 16, 2022
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LGTM

@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 16, 2022
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/merge

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

Commit hash: e92141e

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Mar 16, 2022
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sre-bot commented Mar 16, 2022

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/3956c7d920d6638ecc7d1197fb1dda00d339bec2

@ti-chi-bot ti-chi-bot merged commit 2dd0074 into pingcap:master Mar 16, 2022
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ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 16, 2022
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cherry pick pingcap#33055 to release-4.0
aacab7e 
Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
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cherry pick to release-4.0 in PR #33118

ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 16, 2022
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cherry pick pingcap#33055 to release-5.0
7c5efff 
Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
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cherry pick to release-5.0 in PR #33119

ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 16, 2022
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cherry pick pingcap#33055 to release-5.1
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cherry pick to release-5.1 in PR #33120

ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 16, 2022
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cherry pick pingcap#33055 to release-5.2
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cherry pick to release-5.2 in PR #33121

ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 16, 2022
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cherry pick pingcap#33055 to release-5.3
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cherry pick to release-5.3 in PR #33122

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ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Mar 16, 2022
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cherry pick pingcap#33055 to release-5.4
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cherry pick to release-5.4 in PR #33123

ti-chi-bot pushed a commit that referenced this pull request Apr 14, 2022
@ti-srebot
executor: fix wrong result of delete multiple tables using left join (#…
8e57dd5 
…33055) (#33121)

close #31321
ti-chi-bot pushed a commit that referenced this pull request Apr 26, 2022
@ti-srebot
executor: fix wrong result of delete multiple tables using left join (#…
9dd93df 
…33055) (#33123)

close #31321
ti-chi-bot pushed a commit that referenced this pull request Jun 15, 2022
@ti-srebot
executor: fix wrong result of delete multiple tables using left join (#…
8ac447e 
…33055) (#33122)

close #31321
ti-chi-bot pushed a commit that referenced this pull request Jun 23, 2022
@ti-srebot
executor: fix wrong result of delete multiple tables using left join (#…
5701597 
…33055) (#33120)

close #31321
ti-chi-bot pushed a commit that referenced this pull request Jul 5, 2022
@ti-srebot
executor: fix wrong result of delete multiple tables using left join (#…
1baedb9 
…33055) (#33119)

close #31321
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@wshwsh12 wshwsh12 wshwsh12 approved these changes

@winoros winoros winoros approved these changes

@ekexium ekexium Awaiting requested review from ekexium

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Delete using outer join can mistakenly delete the row whose handle=0
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