handle nulls during cast for like op for ch (#8846)

* handle nulls during cast for like op for ch

* test

* comment

* comment

Author: pjain1

runtime/drivers/olap.go

@@ -304,9 +304,12 @@ func (d Dialect) SupportsILike() bool {
 	return d != DialectDruid && d != DialectPinot && d != DialectStarRocks
 }
 
-// RequiresCastForLike returns true if the dialect requires an expression used in a LIKE or ILIKE condition to explicitly be cast to type TEXT.
-func (d Dialect) RequiresCastForLike() bool {
-	return d == DialectClickHouse
+// GetCastExprForLike returns the cast expression for use in a LIKE or ILIKE condition, or an empty string if no cast is necessary.
+func (d Dialect) GetCastExprForLike() string {
+	if d == DialectClickHouse {
+		return "::Nullable(TEXT)"
+	}
+	return ""
 }
 
 func (d Dialect) SupportsRegexMatch() bool {

runtime/metricsview/astexpr.go

@@ -405,9 +405,7 @@ func (b *sqlExprBuilder) writeILikeCondition(left, right *Expression, leftOverri
 			}
 		}
 
-		if b.ast.Dialect.RequiresCastForLike() {
-			b.writeString("::TEXT")
-		}
+		b.writeString(b.ast.Dialect.GetCastExprForLike())
 
 		if not {
 			b.writeString(" NOT ILIKE ")
@@ -420,9 +418,7 @@ func (b *sqlExprBuilder) writeILikeCondition(left, right *Expression, leftOverri
 			return err
 		}
 
-		if b.ast.Dialect.RequiresCastForLike() {
-			b.writeString("::TEXT")
-		}
+		b.writeString(b.ast.Dialect.GetCastExprForLike())
 	} else if b.ast.Dialect.SupportsRegexMatch() {
 		if not {
 			b.writeString(" NOT ")
@@ -475,9 +471,7 @@ func (b *sqlExprBuilder) writeILikeCondition(left, right *Expression, leftOverri
 				return err
 			}
 		}
-		if b.ast.Dialect.RequiresCastForLike() {
-			b.writeString("::TEXT")
-		}
+		b.writeString(b.ast.Dialect.GetCastExprForLike())
 		b.writeByte(')')
 
 		if not {
@@ -491,9 +485,7 @@ func (b *sqlExprBuilder) writeILikeCondition(left, right *Expression, leftOverri
 		if err != nil {
 			return err
 		}
-		if b.ast.Dialect.RequiresCastForLike() {
-			b.writeString("::TEXT")
-		}
+		b.writeString(b.ast.Dialect.GetCastExprForLike())
 		b.writeByte(')')
 	}
 

runtime/queries/metricsview_aggregation_test.go

@@ -63,6 +63,7 @@ func TestMetricViewAggregationAgainstClickHouse(t *testing.T) {
 	t.Run("testMetricsViewsAggregation_comparison_with_offset_and_limit_and_delta", func(t *testing.T) {
 		testMetricsViewsAggregation_comparison_with_offset_and_limit_and_delta(t, rt, instanceID)
 	})
+	t.Run("testMetricsViewsAggregation_like_nullable", func(t *testing.T) { testMetricsViewsAggregation_like_nullable(t, rt, instanceID) })
 }
 
 func TestMetricViewAggregationAgainstStarRocks(t *testing.T) {
@@ -4959,6 +4960,61 @@ func testMetricsViewAggregation_percent_of_totals_with_limit(t *testing.T, rt *r
 	require.Equal(t, "news.google.com,256.00,0.23", fieldsToString2digits(rows[i], "domain", "total_records", "total_records__pt"))
 }
 
+func testMetricsViewsAggregation_like_nullable(t *testing.T, rt *runtime.Runtime, instanceID string) {
+	// Test LIKE on a Nullable(String) column
+	q := &queries.MetricsViewAggregation{
+		MetricsViewName: "ad_bids_nullable_metrics",
+		Dimensions: []*runtimev1.MetricsViewAggregationDimension{
+			{
+				Name: "publisher",
+			},
+		},
+		Measures: []*runtimev1.MetricsViewAggregationMeasure{
+			{
+				Name: "total_records",
+			},
+		},
+		Where: expressionpb.Like(
+			expressionpb.Identifier("publisher"),
+			expressionpb.Value(structpb.NewStringValue("%oo%")),
+		),
+		Sort: []*runtimev1.MetricsViewAggregationSort{
+			{
+				Name: "publisher",
+			},
+		},
+		SecurityClaims: testClaims(),
+	}
+	err := q.Resolve(context.Background(), rt, instanceID, 0)
+	require.NoError(t, err)
+	require.NotEmpty(t, q.Result)
+
+	rows := q.Result.Data
+	require.Len(t, rows, 3)
+	require.Equal(t, "Facebook,19341", fieldsToString(rows[0], "publisher", "total_records"))
+	require.Equal(t, "Google,18763", fieldsToString(rows[1], "publisher", "total_records"))
+	require.Equal(t, "Yahoo,18593", fieldsToString(rows[2], "publisher", "total_records"))
+
+	// Test NOT LIKE with nullable column — should include NULL publisher rows
+	q.Where = expressionpb.NotLike(
+		expressionpb.Identifier("publisher"),
+		expressionpb.Value(structpb.NewStringValue("%oo%")),
+	)
+	err = q.Resolve(context.Background(), rt, instanceID, 0)
+	require.NoError(t, err)
+	require.NotEmpty(t, q.Result)
+
+	rows = q.Result.Data
+	require.GreaterOrEqual(t, len(rows), 2)
+	// Should contain Microsoft and null publishers
+	publishers := make(map[string]bool)
+	for _, row := range rows {
+		publishers[fieldsToString(row, "publisher")] = true
+	}
+	require.True(t, publishers["Microsoft"])
+	require.True(t, publishers["null"])
+}
+
 func fieldsToString2digits(row *structpb.Struct, args ...string) string {
 	s := make([]string, 0, len(args))
 	for _, arg := range args {

runtime/testruntime/testdata/ad_bids_clickhouse/dashboards/ad_bids_nullable_metrics.yaml

@@ -0,0 +1,9 @@
+type: metrics_view
+model: ad_bids_nullable
+timeseries: timestamp
+dimensions:
+  - column: publisher
+  - column: domain
+measures:
+  - name: total_records
+    expression: COUNT(*)

runtime/testruntime/testdata/ad_bids_clickhouse/models/ad_bids_nullable.sql

@@ -0,0 +1,5 @@
+SELECT
+    toNullable(publisher) AS publisher,
+    toNullable(domain) AS domain,
+    timestamp
+FROM {{ ref "ad_bids_source" }}