外文翻译--关于数据库死锁的知识

外文翻译

About the database of the knowledge of the deadlock Database itself provides lock management mechanism, but from a hand, database is the client applications "puppet", this is mainly because the client to the server has complete control of the gain of locks ability. The client in enquiries in the request and the way to query processing tend to have direct control, so, if we application design reasonable enough, then appear database is normal phenomenon dead lock.

Below are listed some easy to have locked application examples:

A, the client cancel inquires no roll back after practice.

Most of the application is inquires often happens homework. However, users through the front desk the client application inquires the backend database, sometimes will cancel inquires for any variety of reasons. If the user to open the window after mouth query, because users find reflect crash or slow compelled to cancel the query. But, when the client when cancel inquires, if not add rollback transaction statement, then at this time, because the user has to the server sends the inquiry's request, so, the backend database involved in the table, all have been added L locked. So even if the user cancel after inquires, all in the affairs for the locks within will remain. At this point, if other users need to check on the table or the user to open the window through input inquires to query conditions to improve the system response speed occurs when the jam phenomenon.

Second, the client not to get all the results of my query.

Usually, the user will be sent to the server after queries, foreground application must be done at once extraction all the results do. If the application did not extract all the results trip, it produces a problem. For as long as the application did not withdraw promptly all the results, the lock may stay at table and block other users. Since the application has been submitted to the server will SQ statements, the application must be extracted all results do. If the application does not follow the principle words (such as because at that time and no oversight configuration), can't fundamentally solve congestion.

Three, inquires the execution time too long.

Some inquires a relatively long time will cost. As for the query design is not reasonable or query design to watch and record it is, will make inquires the execution time lengthen. If sometimes need to Update on users record or Delete operation, if the line is involved in it, you will get a lot of lock. These locks whether finally upgrade to watch the lock, can block other inquiries.

So often, don't take long time running decision support search and online transaction processing inquires the mixed together.

When database meet blocked, often need to check the application submitted to the SQL statement itself, and check and connection management, all the results do processing and other relevant application behavior. Usually, the lock for to avoid the conflict in the jam, the author has the following Suggestions.

Suggest a: after the completion of the extraction of all query results do.