sql: fix UPSERT RETURNING in presence of schema changes

[jordanlewis]

Fixes #29436.

Release note (bug fix): fix crash caused by certain kinds of UPSERT
RETURNING statements on tables with active schema changes.

[cockroach-teamcity]

This change is 

[vivekmenezes]

Reviewed 3 of 3 files at r1.
Reviewable status: complete! 0 of 0 LGTMs obtained

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pkg/sql/descriptor_mutation_test.go, line 191 at r2 (raw file):

	mTest.Exec(t, `UPSERT INTO t.test VALUES('a', 'bar')`)

	mTest.Exec(t, `UPSERT INTO t.test VALUES('foo') RETURNING k`)

Looks like you only need this statement in this test; right?

Also, could you add an INSERT statement as well. Thanks!

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pkg/sql/tablewriter_upsert.go, line 43 at r2 (raw file):

	// rowIdxToRetIdx maps the indices in the inserted rows
	// back to indices in rowTemplate. Contains -1 for indices in the inserted
	// rows that shouldn't be returned to the user - mutation columns.

how about creating

const dontReturnCol = -1

It will make this code more readable

[jordanlewis]

Thanks, will do. Also, this fix isn't complete, there's another bug lurking... will send another patch.

[jordanlewis]

Reviewable status: complete! 0 of 0 LGTMs obtained

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pkg/sql/descriptor_mutation_test.go, line 191 at r2 (raw file):

Previously, vivekmenezes wrote…

Looks like you only need this statement in this test; right?

Also, could you add an INSERT statement as well. Thanks!

Done.

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pkg/sql/tablewriter_upsert.go, line 43 at r2 (raw file):

Previously, vivekmenezes wrote…

how about creating

const dontReturnCol = -1

It will make this code more readable

Done.

[jordanlewis]

bors r+

[craig]

Build succeeded

• GitHub CI (Cockroach)