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release-24.1: execbuilder: only apply implicit for-update locking to mutation input #121391

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merged 1 commit into from
Apr 24, 2024
Merged

release-24.1: execbuilder: only apply implicit for-update locking to mutation input #121391

merged 1 commit into from
Apr 24, 2024

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@blathers-crl blathers-crl bot commented Mar 29, 2024 •
edited by michae2

Backport 1/1 commits from #121333 on behalf of @michae2.

/cc @cockroachdb/release

In shouldApplyImplicitLockingToMutationInput we match only certain plan shapes of UPDATE and UPSERT, to make certain that implicit for-update locking will not be a pessimization. Then in buildMutationInput we were enabling implicit for-update locking for all operations underneath the input of the mutation.

This was causing subqueries in projections to also have implicit for-update locking, for example in queries like:

UPDATE ab SET b = (SELECT sum(c) FROM c) WHERE a = 1;

In order to restrict implicit for-update locking to the mutation target table, this commit changes shouldApplyImplicitLockingToMutationInput to return the TableID of the input scan. We now only apply implicit for-update locking to these tables.

Fixes: #121322

Release note (bug fix): Fix a bug where UPDATE and UPSERT queries with a subquery were sometimes inappropriately using implicit FOR-UPDATE locking within the subquery. This bug has existing since implicit FOR-UPDATE locking was introduced in 20.1.0.

Release justification: fix for a serious contention issue discovered on the DRT cluster.

@blathers-crl blathers-crl bot requested a review from a team as a code owner March 29, 2024 21:57
@blathers-crl blathers-crl bot force-pushed the blathers/backport-release-24.1-121333 branch from c8c2a7c to 21b3b94 Compare March 29, 2024 21:57
@blathers-crl blathers-crl bot requested review from yuzefovich and removed request for a team March 29, 2024 21:57
@blathers-crl blathers-crl bot added blathers-backport This is a backport that Blathers created automatically. O-robot Originated from a bot. labels Mar 29, 2024
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blathers-crl bot commented Mar 29, 2024 •
edited by michae2

Thanks for opening a backport.

Please check the backport criteria before merging:

  • Backports should only be created for serious
    issues     or test-only changes.
  • Backports should not break backwards-compatibility.
  • Backports should change as little code as possible.
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    here).
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    TL. For more information as to how that review should be conducted, please consult the backport
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  • There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
  • The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
  • New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters. State changes must be further protected such that nodes running old binaries will not be negatively impacted by the new state (with a mixed version test added).
  • The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.
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Also, please add a brief release justification to the body of your PR to justify this
backport.

@blathers-crl blathers-crl bot requested review from mgartner and michae2 March 29, 2024 21:57
@blathers-crl blathers-crl bot added the backport Label PR's that are backports to older release branches label Mar 29, 2024
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@michae2 michae2 force-pushed the blathers/backport-release-24.1-121333 branch 2 times, most recently from 60c0c51 to 5a909aa Compare April 3, 2024 01:08
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michae2 commented Apr 3, 2024

The failure is an unrelated flake. I believe this is RFAL.

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michae2 commented Apr 8, 2024

Gentle ping 🙂

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michae2 commented Apr 12, 2024

Friendly ping @mgartner @yuzefovich

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Reviewed 3 of 5 files at r1, 2 of 2 files at r2, all commit messages.
Reviewable status: :shipit: complete! 0 of 0 LGTMs obtained (waiting on @mgartner and @michae2)

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:lgtm:

Reviewed 3 of 5 files at r1, 2 of 2 files at r2, all commit messages.
Reviewable status: :shipit: complete! 1 of 0 LGTMs obtained (waiting on @michae2)

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Sorry for the delay!

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michae2 commented Apr 23, 2024

Sorry for the delay!

No worries!

@michae2 michae2 force-pushed the blathers/backport-release-24.1-121333 branch from 5a909aa to 4355650 Compare April 23, 2024 21:20
@michae2
execbuilder: only apply implicit for-update locking to mutation input
34e94c1 
In `shouldApplyImplicitLockingToMutationInput` we match only certain
plan shapes of UPDATE and UPSERT, to make certain that implicit
for-update locking will not be a pessimization. Then in
`buildMutationInput` we were enabling implicit for-update locking for
_all_ operations underneath the input of the mutation.

This was causing subqueries in projections to also have implicit
for-update locking, for example in queries like:

```sql
UPDATE ab SET b = (SELECT sum(c) FROM c) WHERE a = 1;
```

In order to restrict implicit for-update locking to the mutation target
table, this commit changes `shouldApplyImplicitLockingToMutationInput`
to return the TableID of the input scan. We now only apply implicit
for-update locking to these tables.

Fixes: #121322

Release note (bug fix): Fix a bug where UPDATE and UPSERT queries with a
subquery were sometimes inappropriately using implicit FOR-UPDATE
locking within the subquery. This bug has existing since implicit
FOR-UPDATE locking was introduced in 20.1.0.
@michae2 michae2 force-pushed the blathers/backport-release-24.1-121333 branch from 4355650 to 34e94c1 Compare April 24, 2024 06:21
@michae2 michae2 merged commit 0561286 into release-24.1 Apr 24, 2024
19 of 20 checks passed
@michae2 michae2 deleted the blathers/backport-release-24.1-121333 branch April 24, 2024 15:29
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@michae2 michae2 michae2 approved these changes

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