Rickard,
Can you explain what you mean by the situation where an update to the
cache arrives after a write resulting in a rollback - which TXN rollsback?
Does this mean that I need to construct a TXN that includes the cache
notify?
Peter Booth
----- Original Message -----
From: "Rickard �berg" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, August 02, 2000 2:09 AM
Subject: Re: optimistic locking and deadlock (was EBs are slow)
[snip much of text ....]
No, the update notifications to the caches to drop stale data can be
sent asynchronously. If the notification comes before an access is made,
then all is fine. If not (and which is the problem you are referring
to), there can be two situations: with a read, stale data will be read.
This may be ok in some situations. With a write, the timestamping will
detect that another cache has changed the data, and a rollback will
occur.
I don't claim it to be perfect, but I do think that it is a very
valuable technique for read-mostly scenarios, and from what I know
read-mostly scenarios are fairly common in web apps.
>> There are more details involved with how to make sure that
>> the nodes don't overwrite each others data if two concurrent
>> tx's modify the same entity.
>
>Gotta finish reading before I start writing...This is the point to which I
>refer. I think "...more details involved..." is an understatement. :-)
Yes. The "more details" I referred to is basically the timestamping
outlined above. (and now you're going to say that the "outline" is too
vague too... ack.. ;-)
/Rickard
--
Rickard �berg
Email: [EMAIL PROTECTED]
http://www.telkel.com
http://www.jboss.org
http://www.dreambean.com
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