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RE: lots of write slowing down searches

Hi Patrick,

For the record, back-ldbm is no longer actively maintained and has a number
of problems. You are always better off using back-bdb or back-hdb as your

Switching to back-bdb would improve search performance during database
modifications. Back-ldbm locks the entire database, so your searches are
blocked for the duration of the modifications, and vice versa. Back-bdb, on
the other hand, uses transactions and fine-grained locking, allowing
searches to continue during operations that modify the database (and
vice-versa). You will still see some degradation in search performance
during write operations, but it should be substantially less. See
http://www.openldap.org/faq/data/cache/756.html for additional information.

Note that OpenLDAP 2.1 has been declared "historic" by the OpenLDAP
foundation, so if you report problems against it you will most likely be
told to upgrade to 2.2.

We are telling our customers to use, and current versions of our OL distro
are based on, OpenLDAP 2.2. It is a substantially better performer, is more
stable, and has more features than OL 2.1, and is actively maintained.

Hope this helps,

Matthew Hardin
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:

> -----Original Message-----
> From: owner-openldap-software@OpenLDAP.org [mailto:owner-openldap-
> software@OpenLDAP.org] On Behalf Of Patrick Radtke
> Sent: Thursday, December 09, 2004 10:32 AM
> To: openldap-software@OpenLDAP.org
> Subject: lots of write slowing down searches
> Hello,
> We have some software that occasionally likes to make lots of
> modifications and adds to OpenLDAP in a short amount of time (5
> modification per sec for a period of 10 minutes).
> When ever this happens all ldapsearches become very slow (servers
> handle about 16 searches per second normally). They take upwards of 2
> seconds where previously the were taking 0.05s to answer requests. This
> causes us various problems with log-ins and email lookups.
> We are running 2.1.30, but I ran tests on 2.2.19 and had the same
> issues.
> we use lbdm as our backend and our indexes are for the standard stuff
> for unix accounts and groups
> I understand that OpenLDAP is read optimized but I am wondering if
> switching to BDB would provide significantly better search speeds when
> writes are occurring (ie enough to solve the problem)?
> The reasons we haven't switched to BDB so far is that it takes extra
> time to build, setup and tune, and I haven't had much extra time:)
> We are planning on fixing our misbehaving software but are just
> concerned that the next time a program does too many writes, everything
> will grind to a halt.
> thanks,
> Patrick Radtke