请教几个DB(or ODBC/JDBC)的问题

[fulpchcl]

1。像Oracle, DB2的比较成熟的DB是不是允许client cancel一个已经发出发出的request,比如说SELECT,UPDATE,DELETE,VALIDATE?
2。如果允许的话Cancle后DB的状态是什么？UPDATE/DELETE应该是roll back吧？那VALIDATE呢？INDEX是在cancel时还是回到VALIDATE前？
3。是不是允许resume cancelled statement，若允许从哪儿开始？是从头开始还是从cancelled的那点开始？比如说一个query要很长时间，会有1000rows返回，cancelled时search result里已经有了500，那resume时是接着做还是从头再来？SELECT好说，VALIDATE化的时间可能更多。
谢先:thanks:

 

[fulpchcl]

玩DB的人应该是蛮多的

没人知道吗？

 

[aruba]

I am trying to answer your questions below:
1. A DB query take effect only after you commit it. Before making commit you can fallback all operations you requested.
2. There is no cancel at query level. But you could cancel/stop a db session if you find a query takes too long to get a result.
3. Normally a DB system won't allow you to alter the physical table space directly and only in a cache. Only when you committed your query, the result in the cache will be written into the table space file.

 

[fulpchcl]

谢谢回复！

我的问题可真够菜鸟的。:blowzy: