feat(postgres): drop indices concurrently in Postgres (#13903)

[feature] Drop indices concurrently in Postgres
This is a follow up to the feature request.
On `removeIndex` it now extends the `options` object
to take in a new attribute, `concurrently`, which
will ensure that the the SQL statement being run
includes `DROP INDEX CONCURRENTLY`...

Having this is nice so developers can use the ORM settings
when dropping an index, safely, instead of having to write
raw SQL.

`concurrently` is a supported attribute on addIndex

lib/dialects/abstract/query-interface.js

@@ -640,12 +640,13 @@ class QueryInterface {
    * @param {string} tableName                    Table name to drop index from
    * @param {string|string[]} indexNameOrAttributes  Index name or list of attributes that in the index
    * @param {object} [options]                    Query options
+   * @param {boolean} [options.concurrently]      Pass CONCURRENTLY so other operations run while the index is created
    *
    * @returns {Promise}
    */
   async removeIndex(tableName, indexNameOrAttributes, options) {
     options = options || {};
-    const sql = this.queryGenerator.removeIndexQuery(tableName, indexNameOrAttributes);
+    const sql = this.queryGenerator.removeIndexQuery(tableName, indexNameOrAttributes, options);
     return await this.sequelize.query(sql, options);
   }
 

lib/dialects/mssql/connection-manager.js

@@ -163,7 +163,7 @@ class ConnectionManager extends AbstractConnectionManager {
   }
 
   validate(connection) {
-    return connection && (connection.loggedIn || (connection.state.name === "LoggedIn"));
+    return connection && (connection.loggedIn || connection.state.name === 'LoggedIn');
   }
 }
 

lib/dialects/postgres/query-generator.js

@@ -412,14 +412,18 @@ class PostgresQueryGenerator extends AbstractQueryGenerator {
     ].join(' ');
   }
 
-  removeIndexQuery(tableName, indexNameOrAttributes) {
+  removeIndexQuery(tableName, indexNameOrAttributes, options) {
     let indexName = indexNameOrAttributes;
 
     if (typeof indexName !== 'string') {
       indexName = Utils.underscore(`${tableName}_${indexNameOrAttributes.join('_')}`);
     }
 
-    return `DROP INDEX IF EXISTS ${this.quoteIdentifiers(indexName)}`;
+    return [
+      'DROP INDEX',
+      options && options.concurrently && 'CONCURRENTLY',
+      `IF EXISTS ${this.quoteIdentifiers(indexName)}`
+    ].filter(Boolean).join(' ');
   }
 
   addLimitAndOffset(options) {

test/unit/dialects/postgres/query-generator.test.js

@@ -1101,9 +1101,15 @@ if (dialect.startsWith('postgres')) {
         }, {
           arguments: ['User', ['foo', 'bar']],
           expectation: 'DROP INDEX IF EXISTS "user_foo_bar"'
+        }, {
+          arguments: ['User', ['foo', 'bar'], { concurrently: true }],
+          expectation: 'DROP INDEX CONCURRENTLY IF EXISTS "user_foo_bar"'
         }, {
           arguments: ['User', 'mySchema.user_foo_bar'],
           expectation: 'DROP INDEX IF EXISTS "mySchema"."user_foo_bar"'
+        }, {
+          arguments: ['User', 'mySchema.user_foo_bar', { concurrently: true }],
+          expectation: 'DROP INDEX CONCURRENTLY IF EXISTS "mySchema"."user_foo_bar"'
         },
 
         // Variants when quoteIdentifiers is false
@@ -1119,6 +1125,10 @@ if (dialect.startsWith('postgres')) {
           arguments: ['User', 'mySchema.user_foo_bar'],
           expectation: 'DROP INDEX IF EXISTS mySchema.user_foo_bar',
           context: { options: { quoteIdentifiers: false } }
+        }, {
+          arguments: ['User', 'mySchema.user_foo_bar', { concurrently: true }],
+          expectation: 'DROP INDEX CONCURRENTLY IF EXISTS mySchema.user_foo_bar',
+          context: { options: { quoteIdentifiers: false } }
         }
       ],