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Re: Storing Docroots in LDAP-DB / OpenLDAP Read Performance

On Sat, 3 Jun 2000, Jochen Tuchbreiter wrote:

> we are planning on using OpenLDAP for storing Docroot-Entries (among other
> things) for Apache (using an external url-rewriting engine).

I can see user ~ maps, but Docroot? Do you really change that information
so often or on so many hosts that includes (managed with M4 or whatever),
mod_perl scripted config files, and "apachectl graceful" won't do?

> Do you guys think that doing one ldap-query per http-query will severly
> reduce the performance of a webslave ? (LDAP-Server running on the same

Yes. But cache the results of the lookup in the Apache child processes or
shared memory and you'll be OK.

Unscientifically, I can tell you that using mod_dav and the MSIE5 "web
folders" feature to list an approximately 200-item directory that was
protected by an LDAP auth module took about 5 seconds on a PII-400. The
single listing actually meant about 500 hits because IE5 likes to PROPFIND
everything and rummage for icons. After rewriting the C module as a
mod_perl module that caches everything (I didn't trust myself to do shared
memory in C), the time was reduced to "unnoticeable."

I remember reading the docs for an Apache module that tried to quantifiy
the benefits of caching the results of queries, but I can't find it on
modules.apache.org right now. Most of the LDAP modules don't do caching
because it's not as easy as it looks.
Rich Graves <rcgraves@brandeis.edu>
UNet Systems Administrator