Heap - optimized bulkload operations with concurrent scan , under these isolation levels : snapshot , read uncommitted , and read committed using row versioning Hobt . bulk _ operation下列隔离级别下的优化堆大容量加载操作与并发扫描:快照、未提交读和使用行版本控制的已提交读。
In order to set read committed snapshot on or off , there must be no active connections to the database except for the connection executing the alter database command 为了将read _ committed _ snapshot设置为on或off ,不应存在任何活动的数据库连接,执行alter database命令的连接除外。
For example , if a transaction changed from read committed to serializable , the shared locks acquired after the change are now held until the end of the transaction 例如,如果某个事务从read committed更改为serializable ,则在该事务结束前,更改后所获取的共享锁将一直处于保留状态。
When the read committed snapshot database option is set off , which is the default setting , read committed isolation behaves as it did in earlier versions of sql server 将read _ commited _ snapshot数据库选项设置为off (默认设置)时,已提交读隔离的行为与在sql server的早期版本中相同。
Because shared locks are held to the end of a transaction instead of being released at the end of each statement , concurrency is lower than the default read committed isolation level 由于共享锁一直保持到事务结束,而不是在每个语句结束时释放,所以并发级别低于默认的read committed隔离级别。