[ZODB-Dev] Question about zeo client cache

[Jim Fulton]

On Sun, Dec 11, 2011 at 4:22 AM, Malthe Borch <mborch at gmail.com> wrote:
> On 10 December 2011 23:41, Maurits van Rees <m.van.rees at zestsoftware.nl> wrote:
>> Disk size is cheap.  I suggest increasing this to a few hundred MB or maybe
>> even a few GB if you have lots of data.  Otherwise you will get a lot of
>> traffic between your zeoclient and server.
>
> If you have very low network latency (essentially if your ZEO is on
> the LAN), there's little point in having a client cache. It's faster
> to pull the data from the ZEO server which either:
>
> 1) has the data you need in its own cache, or
> 2) can load it from disk in which case the network overhead is negligible.
>
> The ZEO client cache is really only suitable for systems where your
> ZEO server is on the internet.

That's really really bad advice.

Even with low latency, your talking on the order of a millisecond for
a round trip to the server.

Data can be loaded from client cache on a 10-20 microseconds if the
data is in the client
disk cache.

If the database is large or if the server is heavily loaded, then
server load times can be'
much worse.  Of course, leaning toward small cache and lots of server
loads makes the server even more heavily loaded.

Jim

-- 
Jim Fulton
http://www.linkedin.com/in/jimfulton