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From "Hunsberger, Peter" <Peter.Hunsber...@stjude.org>
Subject RE: Backend cache invalidation
Date Fri, 23 May 2003 15:44:53 GMT
Arjé Cahn <Arje@hippo.nl> wrote:

> 
> > > I actually thought you wanted to PUSH your new data into the
> > > cache. Which sounds pretty cool anyway. This as opposed to 
> > > getting it from the database on request (and waiting a long 
> > > time for the response).
> > 
> > That seems to be an issue that pops up from time to time.  
> Most common 
> > suggested solution seems to be to run some front end 
> walking package 
> > across the site to do a pre-populate via pull. You're right, push 
> > would be interesting...
> 
> Problem is that you don't exactly know /what/ needs to be 
> updated in the cache when you change a certain object. For 
> example, how do you know whether the results of a SQL 
> statement have changed when you change some value in a table 
> without actually running the query? Although SQL might be 
> pretty easy because you know all the tables and columns it is 
> acting on. 

In our case that wouldn't be too much of a problem as long as the push can
be async. (previous version not invalidated until puch complete).  The proxy
would just blindly refresh the cache with the new data whenever and update,
insert or delete was done (and not try and figure out if it's really
needed).  Since for us refreshes are so rare this wouldn't add much
overhead.


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