Shulou(Shulou.com)05/31 Report--

How to analyze the Sql server lock, I believe that many inexperienced people are at a loss about it. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

There are two ways to classify locks.

(1) from the point of view of database system, locks can be divided into the following three types:

Exclusive lock (Exclusive Lock) the resource locked by an exclusive lock is only allowed by the program that performs the locking operation, and any other operation on it will not be accepted. SQL Server automatically uses exclusive locks when you execute a data update command, that is, the INSERT, UPDATE, or DELETE command. However, an exclusive lock cannot be added to an object when there are other locks on it. The exclusive lock cannot be released until the end of the transaction.

Shared lock (Shared Lock) A resource locked by a shared lock can be read by other users, but other users cannot modify it. When the SELECT command is executed, the SQL Server usually locks the object with a shared lock. Usually, after a data page with a shared lock is read, the shared lock is released immediately.

Update locks (Update Lock) update locks are set up to prevent deadlocks. When SQL Server is ready to update the data, it first makes an update lock on the data object so that the data cannot be modified but can be read. When SQL Server determines that it wants to update the data, it automatically changes the update lock to an exclusive lock. However, when there is another lock on the object, it cannot be updated to lock it.

(2) from the programmer's point of view, locks are divided into the following two types:

Optimistic lock (Optimistic Lock) optimistic lock assumes that when processing data, you can lock the record directly without doing anything in the application's code, that is, relying entirely on the database to manage the lock. In general, SQL Server automatically locks tables that are updated within the scope of a transaction when a transaction is executed.

Pessimistic lock (Pessimistic Lock) pessimistic lock is not interested in the automatic management of database system, so programmers need to directly manage the locking processing on data or objects, and be responsible for acquiring, sharing and relinquishing any locks on the data being used.

After reading the above, have you mastered how to analyze the Sql server lock? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.