colexec: disallow planning CASE operators with unknown WHEN type

[asubiotto]

Release note (bug fix): When vectorize=experimental_on, CASE operators with an
unknown WHEN type fall back to row execution.

Fixes #44726

[cockroach-teamcity]

This change is 

[yuzefovich]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @asubiotto)

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pkg/sql/colexec/execplan.go, line 1247 at r1 (raw file):

			whenResolvedType := whenTyped.ResolvedType()
			// TODO(asubiotto): Can we just plan these as bools?
			if whenTyped.ResolvedType() == types.Unknown {

Maybe the check here should be tighter? Like convert the resolved type into coltypes.T, and if it coltypes.Unhandled, then bail? Or are the only two options here are types.Bool and types.Unknown?

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pkg/sql/colexec/execplan.go, line 1253 at r1 (raw file):

			var whenInternalMemUsed, thenInternalMemUsed int
			caseOps[i], resultIdx, ct, whenInternalMemUsed, err = planTypedMaybeNullProjectionOperators(
				ctx, evalCtx, whenTyped, whenResolvedType, []types.T{*whenResolvedType}, buffer, acc,

I think ct should be passed in and not []types.T{*whenResolvedType}.

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pkg/sql/logictest/testdata/logic_test/vectorize, line 1099 at r1 (raw file):

# Regression test for 44726 (unknown WHEN expression type).
statement ok
CREATE TABLE t44726(c0 INT); INSERT INTO t44726(c0) VALUES (0);

[nit]: unnecessary semicolons.

[asubiotto]

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

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pkg/sql/colexec/execplan.go, line 1253 at r1 (raw file):

Previously, yuzefovich wrote…

I think ct should be passed in and not []types.T{*whenResolvedType}.

This is something I don't understand, why ct? Isn't that the output type of the CASE operator?

[yuzefovich]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @asubiotto)

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pkg/sql/colexec/execplan.go, line 1253 at r1 (raw file):

Previously, asubiotto (Alfonso Subiotto Marqués) wrote…

This is something I don't understand, why ct? Isn't that the output type of the CASE operator?

Updated ct will be the output of the projection operator (and the passed-in ct is the schema of the input to the projection operator).

[asubiotto]

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

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pkg/sql/colexec/execplan.go, line 1247 at r1 (raw file):

Previously, yuzefovich wrote…

Maybe the check here should be tighter? Like convert the resolved type into coltypes.T, and if it coltypes.Unhandled, then bail? Or are the only two options here are types.Bool and types.Unknown?

Done.

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pkg/sql/colexec/execplan.go, line 1253 at r1 (raw file):

Previously, yuzefovich wrote…

Updated ct will be the output of the projection operator (and the passed-in ct is the schema of the input to the projection operator).

I'm still not sure why ct needs to contain the output type of the WHEN clause though. Asking you "offline" to try understand this better. Updated this line as well.

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pkg/sql/logictest/testdata/logic_test/vectorize, line 1099 at r1 (raw file):

Previously, yuzefovich wrote…

[nit]: unnecessary semicolons.

Done.

[yuzefovich]

The release note is not entirely correct - this could occur with auto setting as well since CASE operator is streaming, so this fix will also need to be backported.

Reviewed 2 of 2 files at r2.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @asubiotto and @yuzefovich)

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pkg/sql/colexec/execplan.go, line 1302 at r2 (raw file):

			if whenColType == coltypes.Unhandled {
				return nil, resultIdx, ct, internalMemUsed, errors.Newf(
					"unsupported type %s in CASE WHEN expression", whenTyped.ResolvedType().String())

s/whenTyped.ResolvedType()/whenResolvedType/g (super nit).

[asubiotto]

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

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pkg/sql/colexec/execplan.go, line 1253 at r1 (raw file):

Previously, asubiotto (Alfonso Subiotto Marqués) wrote…

I'm still not sure why ct needs to contain the output type of the WHEN clause though. Asking you "offline" to try understand this better. Updated this line as well.

Thanks for the clarification!

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pkg/sql/colexec/execplan.go, line 1302 at r2 (raw file):

Previously, yuzefovich wrote…

s/whenTyped.ResolvedType()/whenResolvedType/g (super nit).

Done.

[asubiotto]

bors r=yuzefovich

[craig]

Build succeeded

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