Re: BerkeleyDB cache (in apache/mod_perl) vs OS cache

[EMAIL PROTECTED] (Jon Scarbrough) writes:

>Assuming the following - Apache 1.3.29/mod_perl 1.29/BerkeleyDB 4.1.25

>When setting the cache size for the BerkeleyDB environment, will this
>get created for each Apache child process?

No. The cache is in shared memory, see those __db* files in the
environment directory: they are mmapped in all processes using
the environment.

>Is this duplicative of the OS cache?

Yes and no. There is one data copy in the original database file,
and consequently in that file's OS cache, and another one in the
__db* file, shared between OS cache and applications (because it
is a memory mapped file).

Note: I'm not 100% sure that's all true; if not, those helpful
people from sleepycat.com will surely correct me. If they do,
always assume they are right, and I am wrong. :)

best regards
  Patrick