Merge #40610

40610: exec: explicitly check for nulls in selBoolOp r=yuzefovich a=yuzefovich

Previously, we would copy the bool vector from boolVecToSelOp directly.
However, we also need to look at the null values so that nulls are
treated as false. Now this is fixed.

Release note: None

Co-authored-by: Yahor Yuzefovich <yahor@cockroachlabs.com>

pkg/sql/exec/bool_vec_to_sel.go

@@ -123,6 +123,35 @@ func (d selBoolOp) Init() {
 
 func (d selBoolOp) Next(ctx context.Context) coldata.Batch {
 	batch := d.input.Next(ctx)
-	d.boolVecToSelOp.outputCol = batch.ColVec(d.colIdx).Bool()
+	inputCol := batch.ColVec(d.colIdx)
+	d.boolVecToSelOp.outputCol = inputCol.Bool()
+	if inputCol.MaybeHasNulls() {
+		// If the input column has null values, we need to explicitly set the
+		// values of the output column that correspond to those null values to
+		// false. For example, doing the comparison 'NULL < 0' will put true into
+		// the boolean Vec (because NULLs are smaller than any integer) but will
+		// also set the null. In the code above, we only copied the values' vector,
+		// so we need to adjust it.
+		// TODO(yuzefovich): think through this case more, possibly clean this up.
+		outputCol := d.boolVecToSelOp.outputCol
+		n := batch.Length()
+		sel := batch.Selection()
+		nulls := inputCol.Nulls()
+		if sel != nil {
+			sel = sel[:n]
+			for _, i := range sel {
+				if nulls.NullAt(i) {
+					outputCol[i] = false
+				}
+			}
+		} else {
+			outputCol = outputCol[0:n]
+			for i := range outputCol {
+				if nulls.NullAt(uint16(i)) {
+					outputCol[i] = false
+				}
+			}
+		}
+	}
 	return batch
 }

pkg/sql/logictest/testdata/logic_test/vectorize

@@ -835,3 +835,14 @@ SELECT * FROM t40372_1 NATURAL JOIN t40372_2
 1  1  1  1
 2  2  2  2
 3  3  3  3
+
+# Test that comparison against a null value selects the value out.
+statement ok
+CREATE TABLE tnull(a INT, b INT)
+
+statement ok
+INSERT INTO tnull VALUES(NULL, 238)
+
+query I rowsort
+SELECT a FROM tnull WHERE (a<=b OR a>=b)
+----