Remove extra prepare in stdlib

conn.go

@@ -580,14 +580,19 @@ func (c *Conn) getRows(sql string, args []interface{}) *connRows {
 	return r
 }
 
+// QueryResultFormats controls the result format (text=0, binary=1) of a query by result column position.
 type QueryResultFormats []int16
 
+// QueryResultFormatsByOID controls the result format (text=0, binary=1) of a query by the result column OID.
+type QueryResultFormatsByOID map[pgtype.OID]int16
+
 // Query executes sql with args. If there is an error the returned Rows will be returned in an error state. So it is
 // allowed to ignore the error returned from Query and handle it in Rows.
 func (c *Conn) Query(ctx context.Context, sql string, args ...interface{}) (Rows, error) {
 	// rows = c.getRows(sql, args)
 
 	var resultFormats QueryResultFormats
+	var resultFormatsByOID QueryResultFormatsByOID
 
 optionLoop:
 	for len(args) > 0 {
@@ -595,6 +600,9 @@ optionLoop:
 		case QueryResultFormats:
 			resultFormats = arg
 			args = args[1:]
+		case QueryResultFormatsByOID:
+			resultFormatsByOID = arg
+			args = args[1:]
 		default:
 			break optionLoop
 		}
@@ -655,6 +663,13 @@ optionLoop:
 		}
 	}
 
+	if resultFormatsByOID != nil {
+		resultFormats = make([]int16, len(ps.FieldDescriptions))
+		for i := range resultFormats {
+			resultFormats[i] = resultFormatsByOID[ps.FieldDescriptions[i].DataType]
+		}
+	}
+
 	if resultFormats == nil {
 		resultFormats = make([]int16, len(ps.FieldDescriptions))
 		for i := range resultFormats {