Re: (long) Sniffing redo logs to maintain cache consistency?

Following up on , 28 Feb 2003:

>
> But this cascaded warning would only go to the original user.
>
>
> Maybe I'm missing something, but this seems to have a very large
> impact on the users. Rather than getting stale data warnings once
> in a blue moon, wouldn't you get them all the time? Even worse, if you
> look at the data and don't try to change it, you never know it's stale?
> When people complete their tasks, my tasks get changed (in the
> database only) from "Waiting on dependency" to "Ready for you to start",
> but when I view my task list from the cached data, I still see them as
> Waiting. And I will continue to see Waiting until someone updates my tasks
> (through java) and gets a stale data warning, or some kind of checkpoint is
> done.

Tanel replied with what I'd have replied.

I'll just add:

you only get those warnings all the time if you have a system where everyone is hitting the same rows all the time. And even then, like Tanel points out: you have to read the data before you lock it prior to change. Update your Java cache right there and then.

And if you have one of those, then I'm sorry but you don't have a workflow system! You have something else entirely different.

The solution I proposed is for the specific problem this guy has. There is no such thing as a solution that copes with every possible load pattern for every possible application system.

That's why you have different types of patterns in Java design, why you have different types of locking, why you have different designs and implementations: to match the requirements to what you are developing.

"One size fits all" just doesn't exist anywhere.

-- 
Cheers
Nuno Souto
nsouto_at_optusnet.com.au.nospam