Add support for "char"

Postgres offers a type "char" distinct from CHAR,
represented by one byte

Map this type in QValue, sqlserver also has char,
& on clickhouse we can represent it with FixedString(1)

flow/connectors/clickhouse/qvalue_convert.go

@@ -16,6 +16,7 @@ var clickhouseTypeToQValueKindMap = map[string]qvalue.QValueKind{
 	"CHAR":           qvalue.QValueKindString,
 	"TEXT":           qvalue.QValueKindString,
 	"String":         qvalue.QValueKindString,
+	"FixedString(1)": qvalue.QValueKindQChar,
 	"Bool":           qvalue.QValueKindBoolean,
 	"DateTime":       qvalue.QValueKindTimestamp,
 	"TIMESTAMP":      qvalue.QValueKindTimestamp,

flow/connectors/postgres/qvalue_convert.go

@@ -31,6 +31,8 @@ func postgresOIDToQValueKind(recvOID uint32) qvalue.QValueKind {
 		return qvalue.QValueKindFloat32
 	case pgtype.Float8OID:
 		return qvalue.QValueKindFloat64
+	case pgtype.QCharOID:
+		return qvalue.QValueKindQChar
 	case pgtype.TextOID, pgtype.VarcharOID, pgtype.BPCharOID:
 		return qvalue.QValueKindString
 	case pgtype.ByteaOID:
@@ -121,6 +123,8 @@ func qValueKindToPostgresType(colTypeStr string) string {
 		return "REAL"
 	case qvalue.QValueKindFloat64:
 		return "DOUBLE PRECISION"
+	case qvalue.QValueKindQChar:
+		return "\"char\""
 	case qvalue.QValueKindString:
 		return "TEXT"
 	case qvalue.QValueKindBytes:
@@ -262,6 +266,8 @@ func parseFieldFromQValueKind(qvalueKind qvalue.QValueKind, value interface{}) (
 	case qvalue.QValueKindFloat64:
 		floatVal := value.(float64)
 		val = qvalue.QValue{Kind: qvalue.QValueKindFloat64, Value: floatVal}
+	case qvalue.QValueKindQChar:
+		val = qvalue.QValue{Kind: qvalue.QValueKindQChar, Value: uint8(value.(rune))}
 	case qvalue.QValueKindString:
 		// handling all unsupported types with strings as well for now.
 		val = qvalue.QValue{Kind: qvalue.QValueKindString, Value: fmt.Sprint(value)}
@@ -501,10 +507,9 @@ func parseFieldFromQValueKind(qvalueKind qvalue.QValueKind, value interface{}) (
 		}
 	default:
 		textVal, ok := value.(string)
-		if !ok {
-			return qvalue.QValue{}, fmt.Errorf("failed to parse value %v into QValueKind %v", value, qvalueKind)
+		if ok {
+			val = qvalue.QValue{Kind: qvalue.QValueKindString, Value: textVal}
 		}
-		val = qvalue.QValue{Kind: qvalue.QValueKindString, Value: textVal}
 	}
 
 	// parsing into pgtype failed.

flow/connectors/postgres/schema_delta_test_constants.go

@@ -19,6 +19,7 @@ var AddAllColumnTypes = []string{
 	string(qvalue.QValueKindJSON),
 	string(qvalue.QValueKindNumeric),
 	string(qvalue.QValueKindString),
+	string(qvalue.QValueKindQChar),
 	string(qvalue.QValueKindTime),
 	string(qvalue.QValueKindTimestamp),
 	string(qvalue.QValueKindTimestampTZ),
@@ -93,21 +94,26 @@ var AddAllColumnTypesFields = []*protos.FieldDescription{
 	},
 	{
 		Name:         "c13",
-		Type:         string(qvalue.QValueKindTime),
+		Type:         string(qvalue.QValueKindQChar),
 		TypeModifier: -1,
 	},
 	{
 		Name:         "c14",
-		Type:         string(qvalue.QValueKindTimestamp),
+		Type:         string(qvalue.QValueKindTime),
 		TypeModifier: -1,
 	},
 	{
 		Name:         "c15",
-		Type:         string(qvalue.QValueKindTimestampTZ),
+		Type:         string(qvalue.QValueKindTimestamp),
 		TypeModifier: -1,
 	},
 	{
 		Name:         "c16",
+		Type:         string(qvalue.QValueKindTimestampTZ),
+		TypeModifier: -1,
+	},
+	{
+		Name:         "c17",
 		Type:         string(qvalue.QValueKindUUID),
 		TypeModifier: -1,
 	},

flow/connectors/snowflake/avro_file_writer_test.go

@@ -40,6 +40,8 @@ func createQValue(t *testing.T, kind qvalue.QValueKind, placeHolder int) qvalue.
 		value = big.NewRat(int64(placeHolder), 1)
 	case qvalue.QValueKindUUID:
 		value = uuid.New() // assuming you have the github.com/google/uuid package
+	case qvalue.QValueKindQChar:
+		value = uint8(48)
 	// case qvalue.QValueKindArray:
 	// 	value = []int{1, 2, 3} // placeholder array, replace with actual logic
 	// case qvalue.QValueKindStruct:
@@ -85,6 +87,7 @@ func generateRecords(
 		qvalue.QValueKindNumeric,
 		qvalue.QValueKindBytes,
 		qvalue.QValueKindUUID,
+		qvalue.QValueKindQChar,
 		// qvalue.QValueKindJSON,
 		qvalue.QValueKindBit,
 	}

flow/connectors/sql/query_executor.go

@@ -308,6 +308,9 @@ func (g *GenericSQLQueryExecutor) CheckNull(ctx context.Context, schema string,
 }
 
 func toQValue(kind qvalue.QValueKind, val interface{}) (qvalue.QValue, error) {
+	if val == nil {
+		return qvalue.QValue{Kind: kind, Value: nil}, nil
+	}
 	switch kind {
 	case qvalue.QValueKindInt32:
 		if v, ok := val.(*sql.NullInt32); ok {
@@ -341,6 +344,10 @@ func toQValue(kind qvalue.QValueKind, val interface{}) (qvalue.QValue, error) {
 				return qvalue.QValue{Kind: qvalue.QValueKindFloat64, Value: nil}, nil
 			}
 		}
+	case qvalue.QValueKindQChar:
+		if v, ok := val.(uint8); ok {
+			return qvalue.QValue{Kind: qvalue.QValueKindQChar, Value: v}, nil
+		}
 	case qvalue.QValueKindString:
 		if v, ok := val.(*sql.NullString); ok {
 			if v.Valid {

flow/connectors/sqlserver/qvalue_convert.go

@@ -10,6 +10,7 @@ var qValueKindToSQLServerTypeMap = map[qvalue.QValueKind]string{
 	qvalue.QValueKindFloat32:     "REAL",
 	qvalue.QValueKindFloat64:     "FLOAT",
 	qvalue.QValueKindNumeric:     "DECIMAL(38, 9)",
+	qvalue.QValueKindQChar:       "CHAR",
 	qvalue.QValueKindString:      "NTEXT",
 	qvalue.QValueKindJSON:        "NTEXT", // SQL Server doesn't have a native JSON type
 	qvalue.QValueKindTimestamp:   "DATETIME2",
@@ -51,7 +52,7 @@ var sqlServerTypeToQValueKindMap = map[string]qvalue.QValueKind{
 	"UNIQUEIDENTIFIER": qvalue.QValueKindUUID,
 	"SMALLINT":         qvalue.QValueKindInt32,
 	"TINYINT":          qvalue.QValueKindInt32,
-	"CHAR":             qvalue.QValueKindString,
+	"CHAR":             qvalue.QValueKindQChar,
 	"VARCHAR":          qvalue.QValueKindString,
 	"NCHAR":            qvalue.QValueKindString,
 	"NVARCHAR":         qvalue.QValueKindString,

flow/model/qvalue/avro_converter.go

@@ -64,7 +64,7 @@ func GetAvroSchemaFromQValueKind(kind QValueKind, targetDWH QDWHType, precision
 	}
 
 	switch kind {
-	case QValueKindString:
+	case QValueKindString, QValueKindQChar:
 		return "string", nil
 	case QValueKindUUID:
 		return AvroSchemaLogical{
@@ -287,7 +287,8 @@ func (c *QValueAvroConverter) ToAvroValue() (interface{}, error) {
 			return goavro.Union("int.date", t), nil
 		}
 		return t, nil
-
+	case QValueKindQChar:
+		return c.processNullableUnion("string", string(c.Value.Value.(uint8)))
 	case QValueKindString, QValueKindCIDR, QValueKindINET, QValueKindMacaddr:
 		if c.TargetDWH == QDWHTypeSnowflake && c.Value.Value != nil &&
 			(len(c.Value.Value.(string)) > 15*1024*1024) {

flow/model/qvalue/kind.go

@@ -17,6 +17,7 @@ const (
 	QValueKindInt64       QValueKind = "int64"
 	QValueKindBoolean     QValueKind = "bool"
 	QValueKindStruct      QValueKind = "struct"
+	QValueKindQChar       QValueKind = "qchar"
 	QValueKindString      QValueKind = "string"
 	QValueKindTimestamp   QValueKind = "timestamp"
 	QValueKindTimestampTZ QValueKind = "timestamptz"
@@ -63,6 +64,7 @@ var QValueKindToSnowflakeTypeMap = map[QValueKind]string{
 	QValueKindFloat32:     "FLOAT",
 	QValueKindFloat64:     "FLOAT",
 	QValueKindNumeric:     "NUMBER(38, 9)",
+	QValueKindQChar:       "CHAR",
 	QValueKindString:      "STRING",
 	QValueKindJSON:        "VARIANT",
 	QValueKindTimestamp:   "TIMESTAMP_NTZ",
@@ -101,6 +103,7 @@ var QValueKindToClickhouseTypeMap = map[QValueKind]string{
 	QValueKindFloat32:     "Float32",
 	QValueKindFloat64:     "Float64",
 	QValueKindNumeric:     "Decimal128(9)",
+	QValueKindQChar:       "FixedString(1)",
 	QValueKindString:      "String",
 	QValueKindJSON:        "String",
 	QValueKindTimestamp:   "DateTime64(6)",