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AskSQLTeam
Ask SQLTeam Question
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 Posted - 2001-06-04 : 00:55:20
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Laura writes "Hi!
We are working with locks and transactions to allow users to access and update data at the same time. We have two problems:
1) When many users are accessing or updating data, at several times, we experience “dirty reads”.
We don’t set any ISOLATION LEVEL. We think that the default set is READ COMMITTED and SQL assume this option if we don’t set it.
We create a trace with SQL Server Profile to obtain a detailed profile of server events and view that appear sentences like “SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED” at several times.
We don’t type this sentence in our application, and we don’t know if SQL automatically sets the isolation level, or other sentence (in our application) can be executing this SET, or exist a SQL’s parameter that SET the isolation level for ALL sessions.
The effect in our application is that "disapear" records that had been committed (We saw in de trace).We don't know why is it!!!
2) By another, we read that the transaction isolation level allows to set the isolation level for all transaction during a session. But, what is a SQL session? We think that session is a connection. If it’s right, if an application fault in a terminal, the others continue working without problems. However, when this occurs, we lost ALL transaction since this point, like a session was a DATABASE.
Thanks!
Laura" |
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Transaction Isolation Level