Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

release-22.2: opt: fix hoist of ANY comparison with tuples #98769

Merged
merged 1 commit into from
Mar 17, 2023

Conversation

mgartner
Copy link
Collaborator

@mgartner mgartner commented Mar 16, 2023

Backport 1/1 commits from #98700.

/cc @cockroachdb/release


opt: fix hoist of ANY comparison with tuples

Prior to this commit, when hoisting Any expressions like
<left> = ANY (SELECT <right> ...), we constructed
(IsNot <left|right> Null) expressions which are equivalent to
<left|right> IS DISTINCT FROM NULL. As discovered in #46675, these
expressions have different behavior than <left> IS NOT NULL when
<left> is a tuple. As a result, the hoisting transformations could
construct invalid plans that cause incorrect results. This commit fixes
the issue by using IsTupleNotNull expressions when <left> and
` are tupleq.

Fixes #98691

Release note (bug fix): A bug has been fixes that caused incorrect
results of ANY comparisons of tuples. For example, an expression like
(x, y) = ANY (SELECT a, b FROM t WHERE ...) could return true
instead of the correct result of NULL when x and y were NULL, or
a and b were NULL. This could only occur if the subquery was
correlated, i.e., it references columns from the outer part of the
query. This bug was present since the cost-based optimizer was
introduced in version 2.1.

Release justification: Fixes a minor bug.

Prior to this commit, when hoisting Any expressions like
`<left> = ANY (SELECT <right> ...)`, we constructed
`(IsNot <left|right> Null)` expressions which are equivalent to
`<left|right> IS DISTINCT FROM NULL`. As discovered in cockroachdb#46675, these
expressions have different behavior than `<left> IS NOT NULL` when
`<left>` is a tuple. As a result, the hoisting transformations could
construct invalid plans that cause incorrect results. This commit fixes
the issue by using `IsTupleNotNull` expressions when `<left>` and
`<right> are tupleq.

Fixes cockroachdb#98691

Release note (bug fix): A bug has been fixes that caused incorrect
results of ANY comparisons of tuples. For example, an expression like
`(x, y) = ANY (SELECT a, b FROM t WHERE ...)` could return `true`
instead of the correct result of `NULL` when `x` and `y` were `NULL`, or
`a` and `b` were `NULL`. This could only occur if the subquery was
correlated, i.e., it references columns from the outer part of the
query. This bug was present since the cost-based optimizer was
introduced in version 2.1.
@mgartner mgartner requested a review from DrewKimball March 16, 2023 14:19
@mgartner mgartner requested a review from a team as a code owner March 16, 2023 14:19
@blathers-crl
Copy link

blathers-crl bot commented Mar 16, 2023

Thanks for opening a backport.

Please check the backport criteria before merging:

  • Patches should only be created for serious issues or test-only changes.
  • Patches should not break backwards-compatibility.
  • Patches should change as little code as possible.
  • Patches should not change on-disk formats or node communication protocols.
  • Patches should not add new functionality.
  • Patches must not add, edit, or otherwise modify cluster versions; or add version gates.
If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.
  • 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.
  • The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

  • What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
  • Will this work in a cluster of mixed patch versions? Did we test that?
  • If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

@cockroach-teamcity
Copy link
Member

This change is Reviewable

Copy link
Collaborator

@DrewKimball DrewKimball left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

:lgtm:

Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: :shipit: complete! 1 of 0 LGTMs obtained (waiting on @mgartner)

@mgartner mgartner merged commit 73df0dc into cockroachdb:release-22.2 Mar 17, 2023
@mgartner mgartner deleted the backport22.2-98700 branch March 17, 2023 19:39
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

3 participants