1 files changed, 4 insertions, 13 deletions
diff --git a/activerecord/lib/active_record/schema_migration.rb b/activerecord/lib/active_record/schema_migration.rb
index ee4c71f304..b6cb233e03 100644
--- a/activerecord/lib/active_record/schema_migration.rb
+++ b/activerecord/lib/active_record/schema_migration.rb
@@ -16,31 +16,22 @@ module ActiveRecord
         "#{table_name_prefix}#{ActiveRecord::Base.schema_migrations_table_name}#{table_name_suffix}"
       end
 
-      def index_name
-        "#{table_name_prefix}unique_#{ActiveRecord::Base.schema_migrations_table_name}#{table_name_suffix}"
-      end
-
       def table_exists?
         ActiveSupport::Deprecation.silence { connection.table_exists?(table_name) }
       end
 
-      def create_table(limit=nil)
+      def create_table
         unless table_exists?
-          version_options = {null: false}
-          version_options[:limit] = limit if limit
+          version_options = connection.internal_string_options_for_primary_key
 
           connection.create_table(table_name, id: false) do |t|
-            t.column :version, :string, version_options
-            t.index  :version, unique: true, name: index_name
+            t.string :version, version_options
           end
         end
       end
 
       def drop_table
-        if table_exists?
-          connection.remove_index table_name, name: index_name
-          connection.drop_table(table_name)
-        end
+        connection.drop_table table_name, if_exists: true
       end
 
       def normalize_migration_number(number)