Sql server nolock
You can use WITH (NOLOCK) when you are very sure that it’s okay to read uncommitted data otherwise never use WITH (NOLOCK). If you do have code in your application that processes queues and relies on locking to correctly process them, you’re better off using locking hints in that code, and using an optimistic isolation level for the rest of.
#Sql server nolock install
You can use WITH (NOLOCK) for reporting database where data are already written and committed. But in reasonably new versions of SQL Server, tempdb’s setup is part of the install process, and the wacky trace flags you used to have to turn on are the default behavior.
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To SELECT the data WITH (NOLOCK) never requires any lock on the table and it never generates a DEAD LOCK.īut like big banking or finance transaction system, we should not use WITH (NOLOCK) otherwise you may get invalid data which are yet not committed. You should decide whether you want a DEAD LOCK or you want a Wrong Value information. We should consider INSERT, UPDATE and DELETE as a high priority transaction and SELECT as a low priority. WITH (NOLOCK) not only returns wrong values, it also returns phantom records and duplicates. If there are locks on the table, it may make the query faster, but there is a reason locks were invented in the first place. If there are no write locks on a table, it does not make any difference. It is a common misconception that WITH (NOLOCK) always makes the queries run faster.
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READ UNCOMMITED isolation level is equivalent to WITH (NOLOCK). When you are selecting data with this option, that means you are selecting uncommitted data which are yet not permanent and there are still chances to roll back that data.
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Today morning, I got one question from one of my Facebook followers and he raised one question about the use of the TABLE WITH (NOLOCK) of the SQL Server.Įven in our team, what I have found is that some of junior developer every time use WITH (NOLOCK) for all the tables, which is wrong and force me to share the truth about TABLE WITH (NOLOCK) of SQL Server.