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Some Guy wrote:
<blockquote
cite="mid:B4BDFF69-FD97-4CFE-A96D-385068DBFF7B@heroicefforts.net"
type="cite">
<div>All that should be required is to define a version or timestamp
property for the entity in question. Hbn will constrain against that
field when it performs the update. If the db returns 0 updated rows,
then Hbn will throw the stale exception. <br>
</div>
</blockquote>
That's what I thought and did, but wasn't that simple. I think it's
because our persistence approach isn't too friendly with EJB.<br>
<blockquote
cite="mid:B4BDFF69-FD97-4CFE-A96D-385068DBFF7B@heroicefforts.net"
type="cite">
<div><br>
</div>
<div>I recall there's a way to pessimistically lock using db locks
(select for update, etc.), but I assume that's only valid for the
duration of your transaction. I never had call to use it.</div>
<div><br>
</div>
<div>If you use timestamps, make sure your db columns have
millisecond resolution.</div>
<div><br>
On Nov 12, 2009, at 10:18 PM, Mark Proctor <<a moz-do-not-send="true"
href="mailto:mproctor@codehaus.org">mproctor@codehaus.org</a>>
wrote:<br>
<br>
</div>
<blockquote type="cite">
<div>Michael Neale wrote:
<blockquote
cite="mid:50F08D8B-BF74-473E-98A5-FF24DB084FFA@gmail.com" type="cite">
<pre wrap="">I am not aware of peasimistic locking use being very common. When
people want it, it's generally cause the GUI suggests it (eg bob wants
to view a file, but Alice has it locked)
</pre>
</blockquote>
With optimistic locking we can just submit our update and it fails if
something else updted the recorded in the mean time - doing a counter
comparison. With pessemistic we have to download the record first,
compare them, and then upload. As what we are comparing in a binary
blob, we want to avoid pulling that from the db.<br>
<br>
Mark<br>
<blockquote
cite="mid:50F08D8B-BF74-473E-98A5-FF24DB084FFA@gmail.com" type="cite">
<pre wrap="">Sent from my phone.
On 13/11/2009, at 10:27 AM, Salaboy <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E" href="mailto:salaboy@gmail.com"><</a><a
moz-do-not-send="true" href="mailto:salaboy@gmail.com">salaboy@gmail.com</a>> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I suppose that the versión field its being used. So, the default must
be optimistic
- Ing. Mauricio Salatino -
On Nov 12, 2009, at 9:43 PM, Michael Neale <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E" href="mailto:michael.neale@gmail.com"><</a><a
moz-do-not-send="true" href="mailto:michael.neale@gmail.com">michael.neale@gmail.com</a>>
wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I thought optimistic locking was the default ? Or do you mean you
know
how to switch, just that it doesn't work?
Sent from my phone.
On 13/11/2009, at 8:16 AM, Salaboy <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E" href="mailto:salaboy@gmail.com"><</a><a
moz-do-not-send="true" href="mailto:salaboy@gmail.com">salaboy@gmail.com</a>> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I Will take a look on that
Sent from my iPhone
On Nov 12, 2009, at 7:33 PM, Mark Proctor <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E" href="mailto:mproctor@codehaus.org"><</a><a
moz-do-not-send="true" href="mailto:mproctor@codehaus.org">mproctor@codehaus.org</a>>
wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Any hibernate guru's out there? Currently the persistence stuff
uses
pessematic locking, which is slow, in theory we should be using
optimistic locking, but I couldn't get it to work. Anyone want to
give
that a go?
Mark
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