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Re: how to convert "select * from test with(nolock)" to mysql
Posted by: Roland Bouman
Date: April 10, 2006 05:21PM

Ok, from what I read in the ms sql (2000) manual (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnanchor/html/sqlserver2000.asp):

WITH(NOLOCK):
"Do not issue shared locks and do not honor exclusive locks. When this option is in effect, it is possible to read an uncommitted transaction or a set of pages that are rolled back in the middle of a read. Dirty reads are possible. Only applies to the SELECT statement."

would be functionally equivalent to first setting the isolation level (http://dev.mysql.com/doc/refman/5.0/en/innodb-transaction-isolation.html) to read uncommitted:

set transaction isolation level READ UNCOMMITTED;

"READ UNCOMMITTED
SELECT statements are performed in a non-locking fashion, but a possible earlier version of a record might be used. Thus, using this isolation level, such reads are not consistent. This is also called a “dirty read.” Otherwise, this isolation level works like READ COMMITTED. "

and then executing the select. After that, you can of course reset the isolation level.

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Re: how to convert "select * from test with(nolock)" to mysql
April 10, 2006 05:21PM


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