use schema instead of inferred result types

weed/command/sql.go

@@ -295,10 +295,9 @@ func runInteractiveShell(ctx *SQLContext) bool {
 			ctx.currentDatabase = dbName
 			// Also update the SQL engine's catalog current database
 			ctx.engine.GetCatalog().SetCurrentDatabase(dbName)
-				fmt.Printf("Database changed to: %s\n\n", dbName)
-				queryBuffer.Reset()
-				continue
-			}
+			fmt.Printf("Database changed to: %s\n\n", dbName)
+			queryBuffer.Reset()
+			continue
 		}
 
 		// Handle output format switching

weed/query/engine/hybrid_message_scanner.go

@@ -780,8 +780,10 @@ func (hms *HybridMessageScanner) convertJSONValueToSchemaValue(jsonValue interfa
 func (hms *HybridMessageScanner) ConvertToSQLResult(results []HybridScanResult, columns []string) *QueryResult {
 	if len(results) == 0 {
 		return &QueryResult{
-			Columns: columns,
-			Rows:    [][]sqltypes.Value{},
+			Columns:  columns,
+			Rows:     [][]sqltypes.Value{},
+			Database: hms.topic.Namespace,
+			Table:    hms.topic.Name,
 		}
 	}
 
@@ -824,8 +826,10 @@ func (hms *HybridMessageScanner) ConvertToSQLResult(results []HybridScanResult,
 	}
 
 	return &QueryResult{
-		Columns: columns,
-		Rows:    rows,
+		Columns:  columns,
+		Rows:     rows,
+		Database: hms.topic.Namespace,
+		Table:    hms.topic.Name,
 	}
 }
 

weed/query/engine/types.go

@@ -31,4 +31,7 @@ type QueryResult struct {
 	Rows          [][]sqltypes.Value  `json:"rows"`
 	Error         error               `json:"error,omitempty"`
 	ExecutionPlan *QueryExecutionPlan `json:"execution_plan,omitempty"`
+	// Schema information for type inference (optional)
+	Database string `json:"database,omitempty"`
+	Table    string `json:"table,omitempty"`
 }

weed/server/postgres/protocol.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 
 	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/pb/schema_pb"
 	"github.com/seaweedfs/seaweedfs/weed/query/engine"
 	"github.com/seaweedfs/seaweedfs/weed/query/sqltypes"
 	"github.com/seaweedfs/seaweedfs/weed/util/version"
@@ -202,7 +203,7 @@ func (s *PostgreSQLServer) handleSimpleQuery(session *PostgreSQLSession, query s
 		// Send results for this statement
 		if len(result.Columns) > 0 {
 			// Send row description
-			err = s.sendRowDescription(session, result.Columns, result.Rows)
+			err = s.sendRowDescription(session, result)
 			if err != nil {
 				return err
 			}
@@ -324,8 +325,12 @@ func (s *PostgreSQLServer) sendSystemQueryResult(session *PostgreSQLSession, res
 		sqlRows = append(sqlRows, sqlRow)
 	}
 
-	// Send row description
-	err := s.sendRowDescription(session, columns, sqlRows)
+	// Send row description (create a temporary QueryResult for consistency)
+	tempResult := &engine.QueryResult{
+		Columns: columns,
+		Rows:    sqlRows,
+	}
+	err := s.sendRowDescription(session, tempResult)
 	if err != nil {
 		return err
 	}
@@ -418,7 +423,11 @@ func (s *PostgreSQLServer) handleDescribe(session *PostgreSQLSession, msgBody []
 	glog.V(2).Infof("PostgreSQL Describe %c (ID: %d): %s", objectType, session.processID, objectName)
 
 	// For now, send empty row description
-	return s.sendRowDescription(session, []string{}, [][]sqltypes.Value{})
+	tempResult := &engine.QueryResult{
+		Columns: []string{},
+		Rows:    [][]sqltypes.Value{},
+	}
+	return s.sendRowDescription(session, tempResult)
 }
 
 // handleClose processes a Close message
@@ -509,13 +518,13 @@ func (s *PostgreSQLServer) sendReadyForQuery(session *PostgreSQLSession) error {
 }
 
 // sendRowDescription sends row description message
-func (s *PostgreSQLServer) sendRowDescription(session *PostgreSQLSession, columns []string, rows [][]sqltypes.Value) error {
+func (s *PostgreSQLServer) sendRowDescription(session *PostgreSQLSession, result *engine.QueryResult) error {
 	msg := make([]byte, 0)
 	msg = append(msg, PG_RESP_ROW_DESC)
 
 	// Calculate message length
 	length := 4 + 2 // length + field count
-	for _, col := range columns {
+	for _, col := range result.Columns {
 		length += len(col) + 1 + 4 + 2 + 4 + 2 + 4 + 2 // name + null + tableOID + attrNum + typeOID + typeSize + typeMod + format
 	}
 
@@ -525,11 +534,11 @@ func (s *PostgreSQLServer) sendRowDescription(session *PostgreSQLSession, column
 
 	// Field count
 	fieldCountBytes := make([]byte, 2)
-	binary.BigEndian.PutUint16(fieldCountBytes, uint16(len(columns)))
+	binary.BigEndian.PutUint16(fieldCountBytes, uint16(len(result.Columns)))
 	msg = append(msg, fieldCountBytes...)
 
 	// Field descriptions
-	for i, col := range columns {
+	for i, col := range result.Columns {
 		// Field name
 		msg = append(msg, []byte(col)...)
 		msg = append(msg, 0) // null terminator
@@ -544,8 +553,8 @@ func (s *PostgreSQLServer) sendRowDescription(session *PostgreSQLSession, column
 		binary.BigEndian.PutUint16(attrNum, uint16(i+1))
 		msg = append(msg, attrNum...)
 
-		// Type OID (determine from data)
-		typeOID := s.getPostgreSQLType(columns, rows, i)
+		// Type OID (determine from schema if available, fallback to data inference)
+		typeOID := s.getPostgreSQLTypeFromSchema(result, col, i)
 		typeOIDBytes := make([]byte, 4)
 		binary.BigEndian.PutUint32(typeOIDBytes, typeOID)
 		msg = append(msg, typeOIDBytes...)
@@ -722,8 +731,75 @@ func (s *PostgreSQLServer) getCommandTag(query string, rowCount int) string {
 	return "SELECT 0"
 }
 
-// getPostgreSQLType determines PostgreSQL type OID from data
-func (s *PostgreSQLServer) getPostgreSQLType(columns []string, rows [][]sqltypes.Value, colIndex int) uint32 {
+// getPostgreSQLTypeFromSchema determines PostgreSQL type OID from schema information first, fallback to data
+func (s *PostgreSQLServer) getPostgreSQLTypeFromSchema(result *engine.QueryResult, columnName string, colIndex int) uint32 {
+	// Try to get type from schema if database and table are available
+	if result.Database != "" && result.Table != "" {
+		if tableInfo, err := s.sqlEngine.GetCatalog().GetTableInfo(result.Database, result.Table); err == nil {
+			if tableInfo.Schema != nil && tableInfo.Schema.RecordType != nil {
+				// Look for the field in the schema
+				for _, field := range tableInfo.Schema.RecordType.Fields {
+					if field.Name == columnName {
+						return s.mapSchemaTypeToPostgreSQL(field.Type)
+					}
+				}
+			}
+		}
+	}
+
+	// Handle system columns
+	switch columnName {
+	case "_timestamp_ns":
+		return PG_TYPE_INT8 // PostgreSQL BIGINT for nanosecond timestamps
+	case "_key":
+		return PG_TYPE_BYTEA // PostgreSQL BYTEA for binary keys
+	case "_source":
+		return PG_TYPE_TEXT // PostgreSQL TEXT for source information
+	}
+
+	// Fallback to data-based inference if schema is not available
+	return s.getPostgreSQLTypeFromData(result.Columns, result.Rows, colIndex)
+}
+
+// mapSchemaTypeToPostgreSQL maps SeaweedFS schema types to PostgreSQL type OIDs
+func (s *PostgreSQLServer) mapSchemaTypeToPostgreSQL(fieldType *schema_pb.Type) uint32 {
+	if fieldType == nil {
+		return PG_TYPE_TEXT
+	}
+
+	switch kind := fieldType.Kind.(type) {
+	case *schema_pb.Type_ScalarType:
+		switch kind.ScalarType {
+		case schema_pb.ScalarType_BOOL:
+			return PG_TYPE_BOOL
+		case schema_pb.ScalarType_INT32:
+			return PG_TYPE_INT4
+		case schema_pb.ScalarType_INT64:
+			return PG_TYPE_INT8
+		case schema_pb.ScalarType_FLOAT:
+			return PG_TYPE_FLOAT4
+		case schema_pb.ScalarType_DOUBLE:
+			return PG_TYPE_FLOAT8
+		case schema_pb.ScalarType_BYTES:
+			return PG_TYPE_BYTEA
+		case schema_pb.ScalarType_STRING:
+			return PG_TYPE_TEXT
+		default:
+			return PG_TYPE_TEXT
+		}
+	case *schema_pb.Type_ListType:
+		// For list types, we'll represent them as JSON text
+		return PG_TYPE_JSONB
+	case *schema_pb.Type_RecordType:
+		// For nested record types, we'll represent them as JSON text
+		return PG_TYPE_JSONB
+	default:
+		return PG_TYPE_TEXT
+	}
+}
+
+// getPostgreSQLTypeFromData determines PostgreSQL type OID from data (legacy fallback method)
+func (s *PostgreSQLServer) getPostgreSQLTypeFromData(columns []string, rows [][]sqltypes.Value, colIndex int) uint32 {
 	if len(rows) == 0 || colIndex >= len(rows[0]) {
 		return PG_TYPE_TEXT // Default to text
 	}

weed/server/postgres/server.go

@@ -65,13 +65,16 @@ const (
 
 	// PostgreSQL data types
 	PG_TYPE_BOOL      = 16
+	PG_TYPE_BYTEA     = 17
 	PG_TYPE_INT8      = 20
 	PG_TYPE_INT4      = 23
 	PG_TYPE_TEXT      = 25
+	PG_TYPE_FLOAT4    = 700
 	PG_TYPE_FLOAT8    = 701
 	PG_TYPE_VARCHAR   = 1043
 	PG_TYPE_TIMESTAMP = 1114
 	PG_TYPE_JSON      = 114
+	PG_TYPE_JSONB     = 3802
 
 	// Default values
 	DEFAULT_POSTGRES_PORT = 5432