Temporarily patch converters to fix support for LowCardinality strings

pkg/converters/converters.go

@@ -31,6 +31,7 @@ var matchRegexes = map[string]*regexp.Regexp{
 	"FixedString()":             regexp.MustCompile(`^Nullable\(FixedString\(.*\)\)`),
 	"IP":                        regexp.MustCompile(`^IPv[4,6]`),
 	"LowCardinality()":          regexp.MustCompile(`^LowCardinality\(([^)]*)\)`),
+	"LowCardinality(Nullable)":  regexp.MustCompile(`^LowCardinality\(Nullable([^)]*)\)`),
 	"Map()":                     regexp.MustCompile(`^Map\(.*\)`),
 	"Nested()":                  regexp.MustCompile(`^Nested\(.*\)`),
 	"Nullable(Date)":            regexp.MustCompile(`^Nullable\(Date\(?`),
@@ -258,6 +259,17 @@ var Converters = map[string]Converter{
 		matchRegex: matchRegexes["Point"],
 		scanType:   reflect.TypeOf((*interface{})(nil)).Elem(),
 	},
+	// // This is a temporary solution to handle LowCardinality types.
+	// // We'll need to add support for LowCardinality types to `sqlutil` package.
+	"LowCardinality(String)": {
+		fieldType: data.FieldTypeString,
+		scanType:  reflect.PointerTo(reflect.TypeOf("")),
+	},
+	"LowCardinality(Nullable(String))": {
+		fieldType:  data.FieldTypeNullableString,
+		matchRegex: matchRegexes["LowCardinality(Nullable)"],
+		scanType:   reflect.PointerTo(reflect.PointerTo(reflect.TypeOf(""))),
+	},
 }
 
 var ClickhouseConverters = ClickHouseConverters()

pkg/plugin/driver_test.go

@@ -958,6 +958,18 @@ func TestLowCardinalityString(t *testing.T) {
 	}
 }
 
+func TestLowCardinalityNullableString(t *testing.T) {
+	for name, protocol := range Protocols {
+		t.Run(fmt.Sprintf("using %s", name), func(t *testing.T) {
+			conn, close := setupTest(t, "col1 LowCardinality(Nullable(String))", protocol, nil)
+			defer close(t)
+			val := "53"
+			insertData(t, conn, val)
+			checkRows(t, conn, 1, &val)
+		})
+	}
+}
+
 func TestConvertDate32(t *testing.T) {
 	conn := setupConnection(t, clickhouse_sql.Native, nil)
 	canTest, err := plugin.CheckMinServerVersion(conn, 22, 3, 0)