[Zope-dev] ZCatalog caching with memcached

[Hedley Roos]

> 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.
>

No I haven't. Roche Compaan has done extensive benchmarking using
funkload testing plain catalog vs module level cache vs memcached, but
the tests are more about page serving than catalog query time. I'll
ask him to comment more on that.

As for "standard" queries on a Plone site the typical folder contents
query is a good example. The query will be fast unless it sorts on
sortable_title (a ZCTextIndex) right? Not sure right now.

Since memcached is distributed only a single Zope client needs to
perform that query and the result is available to all other Zope
clients. And the cache is "persistent" as long as memcached runs, so
you can merrily restart Zope instances and have a warm cache. I didn't
even realise this until Roche pointed it out to me. To answer the
question: I believe catalogcache will win every time since the return
time of a cached query is not dependent on the complexity of the
query.

We should get a few benchmarks running at query level. I'll have a bit
of time next week.

Hedley