add pointers on how to implement map[string]string

ch/chschema/column.go

@@ -204,8 +204,7 @@ func (c *UUIDColumn) ReadFrom(rd *chproto.Reader, numRow int) error {
 	c.AllocForReading(numRow)
 
 	for i := range c.Column {
-		err := rd.UUID(c.Column[i][:])
+		if err := rd.UUID(c.Column[i][:]); err != nil {
-		if err != nil {
 			return err
 		}
 	}
@@ -557,3 +556,41 @@ func (c BFloat16HistColumn) WriteTo(wr *chproto.Writer) error {
 	}
 	return nil
 }
+
+//------------------------------------------------------------------------------
+
+type MapStringStringColumn struct {
+	ColumnOf[map[string]string]
+}
+
+var _ Columnar = (*MapStringStringColumn)(nil)
+
+func NewMapStringStringColumn() Columnar {
+	return new(MapStringStringColumn)
+}
+
+func (c MapStringStringColumn) Type() reflect.Type {
+	return mapStringStringType
+}
+
+func (c *MapStringStringColumn) ReadFrom(rd *chproto.Reader, numRow int) error {
+	c.AllocForReading(numRow)
+
+	for i := range c.Column {
+		// TODO: implement
+		if err := rd.UUID(c.Column[i][:]); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (c MapStringStringColumn) WriteTo(wr *chproto.Writer) error {
+	for i := range c.Column {
+		v := c.Column[i]
+		// TODO: implement
+		wr.Write(v)
+	}
+	return nil
+}

ch/chschema/types.go

@@ -36,6 +36,8 @@ var (
 
 	sliceUint64Type  = reflect.TypeOf((*[]uint64)(nil)).Elem()
 	sliceFloat32Type = reflect.TypeOf((*[]float32)(nil)).Elem()
+
+	mapStringStringType = reflect.TypeOf((*map[string]string)(nil)).Elem()
 )
 
 var chTypes = [...]string{
@@ -177,6 +179,9 @@ func ColumnFactory(chType string, typ reflect.Type) NewColumnFunc {
 	case "Array(Array(Bool))":
 		return NewArrayArrayStringColumn
 
+	case "Map(String, String)":
+		return NewMapStringStringColumn
+
 	case chtype.Any:
 		return nil
 	}

ch/db_test.go

@@ -322,6 +322,7 @@ func TestClickhouse(t *testing.T) {
 
 	tests := []func(ctx context.Context, t *testing.T, db *ch.DB){
 		testWhereBytes,
+		testMapStringString,
 	}
 	for _, fn := range tests {
 		t.Run(funcName(fn), func(t *testing.T) {
@@ -352,6 +353,10 @@ func testWhereBytes(ctx context.Context, t *testing.T, db *ch.DB) {
 	require.Equal(t, data.Bytes, got.Bytes)
 }
 
+func testMapStringString(ctx context.Context, t *testing.T, db *ch.DB) {
+	// TODO: add test
+}
+
 type Event struct {
 	ch.CHModel `ch:"goch_events,partition:toYYYYMM(created_at)"`