diff --git a/migrator/migrator.go b/migrator/migrator.go
index eafe7bb29..376145998 100644
--- a/migrator/migrator.go
+++ b/migrator/migrator.go
@@ -445,7 +445,7 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 		}
 	}
 
-	if !isSameType {
+	if !isSameType && fullDataType != "mediumtext" && fullDataType != "longtext" {
 		// check size
 		if length, ok := columnType.Length(); length != int64(field.Size) {
 			if length > 0 && field.Size > 0 {
@@ -477,14 +477,6 @@ func (m Migrator) MigrateColumn(value interface{}, field *schema.Field, columnTy
 		}
 	}
 
-	// check unique
-	if unique, ok := columnType.Unique(); ok && unique != field.Unique {
-		// not primary key
-		if !field.PrimaryKey {
-			alterColumn = true
-		}
-	}
-
 	// check default value
 	if !field.PrimaryKey {
 		currentDefaultNotNull := field.HasDefaultValue && !strings.EqualFold(field.DefaultValue, "NULL")