feat(mysql/connection-manager): do not execute SET time_zone query if keepDefaul…

…tTimezone config is true (#9358)

lib/dialects/mysql/connection-manager.js

@@ -124,13 +124,17 @@ class ConnectionManager extends AbstractConnectionManager {
       .tap (() => { debug('connection acquired'); })
       .tap (() => { debug('connection acquired'); })
       .then(connection => {
       .then(connection => {
         return new Utils.Promise((resolve, reject) => {
         return new Utils.Promise((resolve, reject) => {
-        // set timezone for this connection
-        // but named timezone are not directly supported in mysql, so get its offset first
-          let tzOffset = this.sequelize.options.timezone;
-          tzOffset = /\//.test(tzOffset) ? momentTz.tz(tzOffset).format('Z') : tzOffset;
-          connection.query(`SET time_zone = '${tzOffset}'`, err => {
-            if (err) { reject(err); } else { resolve(connection); }
-          });
+          if (!this.sequelize.config.keepDefaultTimezone) {
+            // set timezone for this connection
+            // but named timezone are not directly supported in mysql, so get its offset first
+            let tzOffset = this.sequelize.options.timezone;
+            tzOffset = /\//.test(tzOffset) ? momentTz.tz(tzOffset).format('Z') : tzOffset;
+            return connection.query(`SET time_zone = '${tzOffset}'`, err => {
+              if (err) { reject(err); } else { resolve(connection); }
+            });
+          }
+          // return connection without executing SET time_zone query
+          resolve(connection);
         });
         });
       })
       })
       .catch(err => {
       .catch(err => {

test/integration/dialects/mysql/connector-manager.test.js

@@ -150,5 +150,17 @@ if (dialect === 'mysql') {
           return cm.releaseConnection(connection);
           return cm.releaseConnection(connection);
         });
         });
     });
     });
+
+    it('should acquire a valid connection when keepDefaultTimezone is true', () => {
+      const sequelize = Support.createSequelizeInstance({keepDefaultTimezone: true, pool: {min: 1, max: 1, handleDisconnects: true, idle: 5000}});
+      const cm = sequelize.connectionManager;
+      return sequelize
+        .sync()
+        .then(() => cm.getConnection())
+        .then(connection => {
+          expect(cm.validate(connection)).to.be.ok;
+          return cm.releaseConnection(connection);
+        });
+    });
   });
   });
 }
 }