Merge pull request #16443 from Botik/sequelize-indexes

[sequelize] add where option to DefineIndexesOptions for v4

types/sequelize/index.d.ts

@@ -4792,6 +4792,11 @@ declare namespace sequelize {
          */
         operator?: string;
 
+        /**
+         * Condition for partioal index
+         */
+        where?: WhereOptions;
+
     }
 
     /**

types/sequelize/sequelize-tests.ts

@@ -1290,7 +1290,10 @@ s.define( 'UserWithUniqueUsername', {
             name : 'user_and_email_index',
             unique : true,
             method : 'BTREE',
-            fields : ['user_id', { attribute : 'email', collate : 'en_US', order : 'DESC', length : 5 }]
+            fields : ['user_id', { attribute : 'email', collate : 'en_US', order : 'DESC', length : 5 }],
+            where : {
+                user_id : { $not: null }
+            }
         },
         {
             fields: ['data'],