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Re: bdb cachesize and idlcachesize

--On Tuesday, February 22, 2005 12:15 PM -0500 Dusty Doris <openldap@mail.doris.cc> wrote:

Few questions, if you change the cachesize and idlecachesize entries, do
you have to do anything special aside from restarting slapd, such as run
slapindex or db_recover?

Also, is there any way to tell how much memory these caches are taking up
to make sure they are not set too large?  What happens if you set your
cachesize too large and you don't have enough available memory to store
these?  Will that cause an issue with openldap, or will it just not cache
those entries that would make it exceed its available memory.  Will it
just use some sort of FIFO on those caches?

It will consume the memory resources of your system, and likely cause issues.

Finally, what do most people try to achieve with these values?  Would the
goal be to make these as big as the directory?  So, if I have 400,000 dn's
in my directory, would it be safe to set these at 400000 or would
something like 20,000 be good enough to get a nice performance increase?

I try to cache the most actively used entries. Unless you expect all 400,000 entries of your DB to be accessed regularly, there is no need to cache that many entries. My entry cache is set to 20,000 (out of a little over 400,000 entries).

The idl cache has to do with how many unique result sets of searches you want to store in memory. Setting up this cache will allow your most frequently placed searches to get results much faster, but I doubt you want to try and cache the results of every search that hits your system. ;)


Quanah Gibson-Mount
Principal Software Developer
ITSS/Shared Services
Stanford University
GnuPG Public Key: http://www.stanford.edu/~quanah/pgp.html

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