You can roll back的意思|示意

When you no longer need the ability to roll back the broker, you can delete the broker's system database, unless it is still required for user data.

如果您不再需要回滚代理的功能，那么可以在系统数据库不储存用户数据时删除它。

You can save the current state of the file before the user changes it and then roll back to that at a later point.

你可以在用户改变文件之前保存当前的状态，之后可以进行恢复。

If desired, you can roll back to the prior state simply by clicking a button.

如果需要的话，您只需单击按钮就可以回滚到先前的状态。

By establishing a transaction, you can execute a series of such calls while retaining the ability to roll them back.

借由建立交易，您可执行一系列这种呼叫却仍能保留将其复原的能力。

If a critical resource is unavailable or some other condition prevents the entire transaction from being completed, you can roll back the transaction instead of committing it.

若一个重要的资源已不适用或某些其他的情况造成整个交易不能完成，您可复原此交易而不用认可它。

Permitting nesting leads to situations where the internal transactions succeed, but the parent can still fail — so how do you roll back previously committed children?

允许嵌套会导致内部事务成功，但父事务仍旧可以失败的情况——那么您如何回滚先前提交了的子事务呢？