Exclusive Modes由于行级锁只是一个属性,所以队列的使用方式并不那么简单。当一个事务要去修改某行数据时,按照以下步骤执行:1.如果xmax和hint bits标明当前行被不兼容的模式锁定,那么该事务就会申请一个要修改的元组的重量级锁(元组锁,和row-level lock不一样)。2.如果有必要,请求xmax字段记录事务的ID锁(之前介绍...
* Decode the locktag back to the original values, to avoid sending lots of empty bytes with every message. See lock.h to check how a locktag is defined for LOCKTAG_RELATION */ LogAccessExclusiveLock(locktag->locktag_field1, locktag->locktag_field2); } return LOCKACQUIRE_OK; } 1. ...