opt: wrap virtual computed column projections in a cast

[mgartner]

sql/logictest: remove assignment cast TODO

This commit removes a TODO that was partially addressed by #82022.

Informs #73743

Release note: None

sql/types: fix T.Identical

This commit fixes a bug in types.T.Identical which caused it to return
false for collated string types with a different string-representation
of locales that represents the same locale logically. For example,
collated string types with locales en_US and en_us would not be
identical, even though these are both valid representations of the same
locale.

There is no release note because this has not caused any known bugs.

Release note: None

opt: wrap virtual computed column projections in a cast

optbuilder wraps an assignment cast around a virtual computed column
expression when writing to the table if the expression does not have the
same type as the virtual column. This matches the behavior of all writes
to columns of expressions that don't match the target column type.

However, the same cast was not applied to the projection of the virtual
column expression when reading from the table. This cast is necessary in
order to produce the correct value of the column - the projection must
produce the same value that would have been written to the table if the
column was a stored computed column. This commit corrects optbuilder so
that the cast is correctly added to the projection.

Note that this commit adds a standard cast, not an assignment cast, as a
temporary workaround until #81698 is addressed. This is because an
assignment cast can fail in cases when a regular cast will not. Because
we don't validate that all existing rows can successfully produce a new
virtual column expression during a backfill, adding an assignment cast
to the projection of the virtual column could cause future reads to
error. Once #81698 is addressed, we can change these casts to assignment
casts so that they directly match the values that would be written to
the same column if it were stored.

Fixes #91817
Informs #81698

Release note (bug fix): A bug has been fixed that could produce incorrect
values for virtual computed columns in rare cases. The bug only
presented when the virtual column expression's type did not match the
type of the virtual column.

[cockroach-teamcity]

This change is 

[mgartner]

Hold off on reviewing - looks like this regressed some query plans. I'll see if there's a way to fix that.

[yuzefovich]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @DrewKimball, @mgartner, and @msirek)

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-- commits line 6 at r1:
Probably #73743.

[mgartner]

This should be ready for a look now.

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @DrewKimball, @msirek, and @yuzefovich)

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-- commits line 6 at r1:

Previously, yuzefovich (Yahor Yuzefovich) wrote…

Probably #73743.

Fixed, thanks.

[msirek]

Reviewed 1 of 1 files at r1, 6 of 6 files at r3, 2 of 2 files at r4, 7 of 8 files at r5, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @DrewKimball, @mgartner, and @yuzefovich)

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-- commits line 34 at r5:
nit: "the correct the value" --> "the correct value"

[msirek]

Is the fix for #73743 coming in a separate PR?

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @DrewKimball, @mgartner, and @yuzefovich)

[DrewKimball]

Reviewed 1 of 1 files at r1, 6 of 6 files at r3, 2 of 2 files at r4, 8 of 8 files at r5, all commit messages.
Reviewable status: complete! 2 of 0 LGTMs obtained (waiting on @mgartner and @yuzefovich)

[mgartner]

Is the fix for #73743 coming in a separate PR?

I have no plans to fix that one at the moment. I would like to address #81698 soon, though - it can cause lots of problems.

Reviewable status: complete! 0 of 0 LGTMs obtained (and 2 stale) (waiting on @yuzefovich)

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-- commits line 34 at r5:

Previously, msirek (Mark Sirek) wrote…

nit: "the correct the value" --> "the correct value"

Done.

[mgartner]

TFTRs!

bors r+

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)

[mgartner]

blathers backport 23.1

[blathers-crl]

Based on the specified backports for this PR, I applied new labels to the following linked issue(s). Please adjust the labels as needed to match the branches actually affected by the issue(s), including adding any known older branches.

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Issue #91817: branch-release-23.1.

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[blathers-crl]

Encountered an error creating backports. Some common things that can go wrong:

1. The backport branch might have already existed.
2. There was a merge conflict.
3. The backport branch contained merge commits.

You might need to create your backport manually using the backport tool.

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error creating merge commit from ab5e955 to blathers/backport-release-23.1-105736: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 23.1 failed. See errors above.

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