Merge pull request #156979 from cockroachdb/blathers/backport-release-25.4-156962

release-25.4: colexec: fix projections with constant NULL values

Author: mgartner

pkg/sql/colexec/colbuilder/execplan.go

@@ -2828,11 +2828,16 @@ func planProjectionExpr(
 		resultIdx = len(typs)
 		// The projection result will be outputted to a new column which is
 		// appended to the input batch.
-		// TODO(#127814): We may need to handle the case when the left is DNull.
-		op, err = colexecprojconst.GetProjectionLConstOperator(
-			allocator, typs, left.ResolvedType(), outputType, projOp, input,
-			rightIdx, lConstArg, resultIdx, evalCtx, binOp, cmpExpr, calledOnNullInput,
-		)
+		if !calledOnNullInput && (left == tree.DNull || right == tree.DNull) {
+			// If the left or right is NULL and the operator is not called on
+			// NULL, simply project NULL.
+			op = colexecbase.NewConstNullOp(allocator, outputType, input, resultIdx)
+		} else {
+			op, err = colexecprojconst.GetProjectionLConstOperator(
+				allocator, typs, left.ResolvedType(), outputType, projOp, input,
+				rightIdx, lConstArg, resultIdx, evalCtx, binOp, cmpExpr, calledOnNullInput,
+			)
+		}
 	} else {
 		var leftIdx int
 		input, leftIdx, typs, err = planProjectionOperators(

pkg/sql/logictest/testdata/logic_test/vectorize

@@ -1343,3 +1343,26 @@ statement ok
 RESET vectorize
 
 subtest end
+
+# Regression test for #152771. Gracefully plan operators that cannot handle NULL
+# inputs.
+statement ok
+CREATE TABLE t152771 (i INT)
+
+statement ok
+INSERT INTO t152771 VALUES (0)
+
+statement ok
+SET plan_cache_mode = force_generic_plan
+
+statement ok
+PREPARE p(INT, INT, INT, INT) AS UPDATE t152771 SET i=($1-$2)+($3-$4)
+
+statement ok
+EXECUTE p(NULL, 3, 33, NULL)
+
+statement ok
+DEALLOCATE p
+
+statement ok
+RESET plan_cache_mode