bdb cachesize and idlcachesize

[Dusty Doris <openldap@mail.doris.cc>]

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?

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 am trying to setup an environment to test all these config items in, but
for now, I was hoping to get some insight from the experts.

Thanks
Dusty Doris