colexec: reject CASE operator with Bytes output type

pkg/sql/colexec/execplan.go

@@ -1193,7 +1193,15 @@ func planProjectionOperators(
 		buffer := NewBufferOp(input)
 		caseOps := make([]Operator, len(t.Whens))
 		caseOutputType := typeconv.FromColumnType(t.ResolvedType())
-		if caseOutputType == coltypes.Unhandled {
+		switch caseOutputType {
+		case coltypes.Bytes:
+			// Currently, there is a contradiction between the way CASE operator
+			// works (which populates its output in arbitrary order) and the flat
+			// bytes implementation of Bytes type (which prohibits sets in arbitrary
+			// order), so we reject such scenario to fall back to row-by-row engine.
+			return nil, resultIdx, ct, internalMemUsed, errors.Newf(
+				"unsupported type %s in CASE operator", t.ResolvedType().String())
+		case coltypes.Unhandled:
 			return nil, resultIdx, ct, internalMemUsed, errors.Newf(
 				"unsupported type %s", t.ResolvedType().String())
 		}

pkg/sql/logictest/testdata/logic_test/vectorize

@@ -1083,3 +1083,13 @@ CREATE TABLE t44304(c0 INT); INSERT INTO t44304 VALUES (0)
 query I
 SELECT * FROM t44304 WHERE CASE WHEN t44304.c0 > 0 THEN NULL END
 ----
+
+# Regression test for CASE operator and flat bytes.
+statement ok
+CREATE TABLE t44624(c0 STRING, c1 BOOL); INSERT INTO t44624(rowid, c0, c1) VALUES (0, '', true), (1, '', NULL)
+
+query TB
+SELECT * FROM t44624 ORDER BY CASE WHEN c1 IS NULL THEN c0 WHEN true THEN c0 END
+----
+·  true
+·  NULL