Re: postfix LDAP lookup caching

Zitat von G=E1bor L=E9n=E1rt <lgb@lgb.hu>:

> Hi,
>
> We've some MTAs under quite big load. Since there're several MTAs (not
> only postfix) on different operating systems as well, we use LDAP as
> a "common language" between systems, and of course to keep result of
> table loopups in sync (with LDAP replication for local ldap servers).
>
> However it seems the quite big load generating rapid amount of LDAP que=
ries
> is not handled fast enough by LDAP servers. So it would be nice if the
> result of the lookup would be cached by Postfix (caching for maximum of
> 10sec is quite good, modifications in LDAP structure does not a problem=
if
> it realizes within about one minute or so). However as I read from the
> documentation, caching function in LDAP lookup handler was dropped. I'v=
e
> tried to use proxymap as well, but as far as I understand that is not f=
or
> caching only for proxying for security and/or lowering the number of
> multiple queries with sharing the same connection through.
>
> So my problem remains: how can I cache lookup results? The wild idea wi=
ll be
> to use local eg hash maps (which are faster for simple lookups than usi=
ng
> ldap I guess) and use some perl or shell backend functionality in OpenL=
DAP
> to update that hash maps regurally when modification arrives via LDAP
> replication from the master LDAP server.
>
> Note, that eg recipient check on the inbound mail server requires quite
> large (>100K) but linear table besides transport map definitions and so=
..

Just some hints :
- Double check the indexing on the LDAP db for attributes used by your ma=
ilers.
A recent directory server should be able to handle a lot of queries.
- Have a look at the "domain" parameter (man ldap_table) from postfix. Th=
is
*might* save some queries depending on your needs.
- Maybe using a local slave LDAP server can help if your mailers are not
CPU/Memory limited.
- The best scalability/performance was reported with local hash/btree map=
s
exported from the LDAP dir.

Regards

Andreas