问题
I know the default TRANSACTION ISOLATION LEVEL in SQL Server is "read committed". If I want to change it to "READ UNCOMMITTED", how may i make this configuration change?
note: I cannot use SET TRANSACTION ISOLATION LEVEL, which only apply in the current session. I cannot add NOLOCK in the queries because there are thousands of queries involved.
Thanks
Thanks for your answer. We are ok with reading dirty rows. Update is not a problem in our case as well. but, I really want to change this default config of isolation level. Please kindly help.
I cannot "SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED". I must make the global change.
We have carefully reviewed both snapshot isolation level. They cannot be used in our situation.
回答1:
I really do not think you should set that at a global level. You should be setting this pretty carefully because you can end up with a lot of different problems:
- Lost Updates
- Non repeatable reads
- Dirty reads
- Phantom reads
There is no way to set this at a database or a server level - it can only be set at a connection level.
The best you can do at a database level is to set the ALLOW_SNAPSHOT_ISOLATION or READ_COMMITTED_SNAPSHOT properties. Read more here:
http://msdn.microsoft.com/en-us/library/tcbchxcb%28VS.80%29.aspx
回答2:
What about:
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
It will only apply to the current transaction.
来源：https://stackoverflow.com/questions/1670673/how-may-i-change-the-default-transaction-isolation-level-in-sql-server-2005