未授权读取 也称为读未提交(Read Uncommitted):允许脏读取,但不允许更新丢失。如果一个事务已经开始写数据,则另外一个数据则不允许同时进行写操作,但允许其他事务读此行数...
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会发生不可重读、幻像读和读未提交数据。
An unrepeatable read, phantom read, and reads of uncommitted data can occur.
将分割镜像初始化为快照时,将执行崩溃恢复,回滚所有未提交的事务,并使数据库可以被所有读或写操作访问。
The initialization of the split mirror as snapshot performs a crash recovery, rolls back all uncommitted transactions, and makes the database available for any read or write operation.
例如,如果一个成员正在更新一行数据,那么另一个成员就不能以未提交读(uncommitted read)以外的任何隔离级别读取这一行。
For example, if one member is updating a row, it would not be proper for another member to read the row with any other isolation level than uncommitted read.
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