Craft CMS with Google Cloud SQL as backend database
Craft currently won't operate properly if you have GTID enabled because GTID enforces that every table involved in a SQL statements in one transaction have to utilize the same storage engine.

While virtually all of Craft's tables use InnoDB as the storage engine, the craft_searchindex table is still on MyISAM, because InnoDB didn't add full-text support until MySQL 5.6 and Craft still supports back to MySQL 5.1.

If you're running MySQL 5.6+ (which you should be because I don't believe GTID was introduced until 5.6), then you can manually change the storage engine of the craft_searchindex table from MyISAM to InnoDB and you shouldn't run into any issues.