diff --git a/dialect_postgres.go b/dialect_postgres.go
index 18cbe028..09ac5961 100644
--- a/dialect_postgres.go
+++ b/dialect_postgres.go
@@ -45,6 +45,10 @@ func (postgres) DataTypeOf(field *StructField) string {
 		case reflect.Float32, reflect.Float64:
 			sqlType = "numeric"
 		case reflect.String:
+			if _, ok := field.TagSettings["SIZE"]; !ok {
+				size = 0 // if SIZE haven't been set, use `text` as the default type, as there are no performance different
+			}
+
 			if size > 0 && size < 65532 {
 				sqlType = fmt.Sprintf("varchar(%d)", size)
 			} else {