Re: using DBI for mutual exclusion across multiple servers

On Thu, Mar 11, 2010 at 1:57 PM, Jonathan Swartz <[email protected]> wrote:

> Ok. Sounds like this is more expensive than I expected (at least in
> Oracle's case).
>
> Does it save any cost that the update is a "dummy" update, "update id = 1
> where id = 1"? That is, I'm only using the update to reserve the row, not
> actually changing any data.
>
>
That is database and database version dependent.

The best way to discover the answer to this would be to
run a trace of the operations. In the case of Oracle that
would be a 10046 trace. I don't know about others.

Is this being done on an Oracle database?

If so a much better way IMO would be to use the DBMS_LOCK
package that is part of the database.

The package has the advantage of automatically releasing a lock
when the session ends.


Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
Oracle Blog: http://jkstill.blogspot.com
Home Page: http://jaredstill.com