[Zope-dev] ZCatalog caching with memcached

[Andreas Jung]

On 25.10.2008 8:48 Uhr, Hedley Roos wrote:
> The usual Plone catalogs (portal_catalog, uid_catalog,
> reference_catalog and membrane_tool) all run above 90% hit rate if the
> server is up to it. portal_catalog is invalidated the most so it
> fluctuates the most.
>
> If the server is severely underpowered then catalogcache is much less
> effective. portal_catalog hit rates will degrade over time. This is
> the situation I'm currently facing with on one site, but more servers
> will fix that.
>
> It's quite easy to benchmark / load test with funkload. What I've
> found is that memcached is very light on CPU, but if the Zope
> processes are constantly using all CPU it is starved and runs into
> trouble. As long as you avoid that case (which would be fatal without
> catalogcache in any case) then everything works perfectly.
>

Have you measures the time needs for some "standard" ZCatalog queries
used with a Plone site with the communication overhead with memcached?
Generally spoken: I think the ZCatalog is in general fast. Queries using 
a fulltext index are known to be more expensive or if you have to deal 
with large resultsets or complex queries.

Andreas
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