On Fri, Feb 10, 2012 at 4:49 AM, Pedro Ferreira <jose.pedro.ferre...@cern.ch> wrote: > Hello all, > > A (possibly silly) question: does ZEO have some kind of server-side cache? I > mean, each time an oid is requested by one of the clients is it retrieved > from the DB file directly, or are some of the objects kept in memory? From > what I see in the code, the latter doesn't seem to happen.
No -- and yes. :) The OS' file-system cache acts as a storage server cache. The storage server does (essentially) no processing to data read from disk, so an application-level cache would add nothing over the disk cache provided by the storage server. Also note that, for better or worse, FileStorage uses an in-memory index of current record positions, so no disk access is needed to find current data. > I know there are client-side caches, but in a multiple client/server context > I wonder if it's not faster to ask the DB for an oid that is already in > memory instead of retrieving it from the client cache? In general, I'd say no. It can depend on lots of details, including: - database size - active set size - network speed - memory and disk speeds on clients and servers - ... Jim -- Jim Fulton http://www.linkedin.com/in/jimfulton _______________________________________________ For more information about ZODB, see http://zodb.org/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
