Backport: Add option to restart identity when truncate (#6417)

Issue #5356

  - update query interface with option restartIdentity
  - add test for option restartIdentity
  - update documentation for option restartIdentity with truncate
  - add restartIdentity entry in changelog

changelog.md

+# Future
+- [ADDED] `restartIdentity` option for truncate in postgres [#5356](https://github.com/sequelize/sequelize/issues/5356)
+
 # 3.23.5
 - [FIXED] Fixed an issue where custom-named model fields break when offsetting, ordering, and including hasMany simultaneously. [#5985](https://github.com/sequelize/sequelize/issues/5985)
 - [FIXED] Don't remove includes from count queries and unify findAndCount and count queries. [#6123](https://github.com/sequelize/sequelize/issues/6123)

docs/api/model.md

@@ -725,6 +725,7 @@ Delete multiple instances, or set their deletedAt timestamp to the current time
 | [options.force=false] | Boolean | Delete instead of setting deletedAt to current timestamp (only applicable if `paranoid` is enabled) |
 | [options.truncate=false] | Boolean | If set to true, dialects that support it will use TRUNCATE instead of DELETE FROM. If a table is truncated the where and limit options are ignored |
 | [options.cascade=false] | Boolean | Only used in conjunction with TRUNCATE. Truncates all tables that have foreign-key references to the named table, or to any tables added to the group due to CASCADE. |
+| [options.restartIdentity=false] | Boolean | Only used in conjunction with TRUNCATE. Automatically restart sequences owned by columns of the truncated table. Postgres only. |
 | [options.transaction] | Transaction | Transaction to run query under |
 | [options.logging=false] | Function | A function that gets executed while running the query to log the sql. |
 | [options.benchmark=false] | Boolean | Print query execution time in milliseconds when logging SQL. |

lib/dialects/postgres/query-generator.js

@@ -350,6 +350,10 @@ var QueryGenerator = {
         query += ' CASCADE';
       }
 
+      if (options.restartIdentity) {
+        query += ' RESTART IDENTITY';
+      }
+
       return query;
     }
 

lib/model.js

@@ -2240,6 +2240,7 @@ Model.prototype.truncate = function(options) {
  * @param  {Boolean}      [options.force=false]           Delete instead of setting deletedAt to current timestamp (only applicable if `paranoid` is enabled)
  * @param  {Boolean}      [options.truncate=false]        If set to true, dialects that support it will use TRUNCATE instead of DELETE FROM. If a table is truncated the where and limit options are ignored
  * @param  {Boolean}      [options.cascade=false]         Only used in conjunction with TRUNCATE. Truncates  all tables that have foreign-key references to the named table, or to any tables added to the group due to CASCADE.
+ * @param  {Boolean}      [options.restartIdentity=false] Only used in conjunction with TRUNCATE. Automatically restart sequences owned by columns of the truncated table.
  * @param  {Transaction}  [options.transaction] Transaction to run query under
  * @param  {Function}     [options.logging=false]         A function that gets executed while running the query to log the sql.
  * @param  {Boolean}      [options.benchmark=false]       Pass query execution time in milliseconds as second argument to logging function (options.logging).
@@ -2262,7 +2263,8 @@ Model.prototype.destroy = function(options) {
     hooks: true,
     individualHooks: false,
     force: false,
-    cascade: false
+    cascade: false,
+    restartIdentity: false
   });
 
   options.type = QueryTypes.BULKDELETE;

test/unit/sql/delete.test.js

@@ -43,6 +43,33 @@ suite(Support.getTestDialectTeaser('SQL'), function() {
       });
     });
 
+    suite('truncate with cascade and restartIdentity', function () {
+      var options = {
+        table: User.getTableName(),
+        where: {},
+        truncate: true,
+        cascade: true,
+        restartIdentity: true,
+        limit: 10
+      };
+
+      test(util.inspect(options, {depth: 2}), function () {
+        return expectsql(
+          sql.deleteQuery(
+            options.table,
+            options.where,
+            options,
+            User
+          ), {
+            postgres: 'TRUNCATE "public"."test_users" CASCADE RESTART IDENTITY',
+            mssql:    'TRUNCATE TABLE [public].[test_users]',
+            mysql:    'TRUNCATE `public.test_users`',
+            sqlite:   'DELETE FROM `public.test_users`'
+          }
+        );
+      });
+    });
+
     suite('delete without limit', function () {
       var options = {
         table: User.getTableName(),