As for the concurrent control techniques the prototype system implements the method of pessimistic locking with accordance to the features of the graphic objects that CAD systems operate on.

A pessimistic locking strategy assumes that the probability is high that another user will try to modify the same row in a table that you are changing.

悲观锁定策略的前提是，另一个用户很可能试图修改您正在修改的某个表行。

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However, this should be evaluated on a case by case basis& there are situations where pessimistic locking is necessary.

但是，在实际使用中应根据具体情况进行分析，有时也需要悲观锁定方案。

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The advantage of pessimistic locking is that it is guaranteed that changes are made consistently and safely.

悲观锁定的优点就是能够保证实现一致且安全的更改。

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Pessimistic locking, where a record is locked while it is edited.

悲观的锁定，在编辑记录时将其锁定。

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The main problem with a pessimistic locking approach is that transactions have to wait for each other.

悲观锁定方法的主要问题是事务之间必须互相等待。

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Fixed FOR UPDATE statements not generated for pessimistic locking

修复了不会生成悲观锁定的FOR UPDATE语句

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Certain critical updates should always be done with pessimistic locking.

进行特定的关键性更新时，应始终使用悲观锁定方式。

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Note that applications that do not use this programming model are not considered optimistic locking applications, and they will continue to work as before.

注意，未使用这种编程模型的应用程序被认为是非乐观锁定应用程序，它们将按照以前的方式工作。

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Instead, we recommend the use of an optimistic locking strategy, delegating responsibility for concurrency control to appropriate application logic.

我们建议采用乐观锁定策略，将并发控制的责任委派给相应的应用程序逻辑。

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For instance, if the application uses pessimistic locking, don't change the application during the migration to use optimistic locking.

例如，如果应用程序使用悲观锁定，则在迁移过程中不要将应用程序更改为使用乐观锁定。

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Note that without DDL changes, optimistic locking applications may get more false negatives than with DDL changes.

注意，在不进行DDL修改的情况下，乐观锁定应用程序可能会产生更多的漏判（false negative）。

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If the workload is a read mostly workload, then solutions like caching with optimistic locking work well.

如果工作负荷主要是读取，那么诸如使用最优锁定进行缓存的解决方案可以很有效。

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There are other possible optimistic locking strategies and detailed design work is needed to devise suitable concurrency schemes.

另外，还需要一些其他可能的乐观锁定策略和详细设计，以制定合适的并发方案。

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Optimistic locking, where a record is locked only when changes are committed to the database.

乐观的锁定，只当数据库发生更改时锁定记录。

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In this case, there may need to be some application restructuring, or optimistic locking may need to be used instead.

这时，可能需要修改应用程序，或使用乐观锁定方式。

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This represents a simplified form of what the database world calls optimistic locking.

这是数据库调用乐观（optimistic）锁的简单方式。

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Applications using this programming model will benefit from the enhanced optimistic locking feature.

使用这种编程模型的应用程序将从增强的乐观锁定特性中获益。

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The workmen even made me two little chairs and a table ， and a lock for the door ， so that no rats could get in.

工匠甚至还给我做了两个小椅子和一张桌子，一把门锁，这样老鼠就进不去了。

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When using UR in application A1 on selecting multiple rows, there will be an IN ( intent none) table lock on the accessed table.

在应用程序A1中使用UR来选择多行时，所访问的表中将有一个IN（intent none）表锁定。

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Enterprise Manager might display TM for any table lock, rather than indicate the mode of table lock ( such as RS or SRX).

每种锁类型或锁模式后面的圆括号里面的缩写，被用在企业管理器的锁监控器软件上。

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