Re: delete members in big groups with back_mdb

[Marco Schirrmeister <marco@schirrmeister.net>]

On Jul 17, 2013, at 7:08 PM, Quanah Gibson-Mount <quanah@zimbra.com> wrote:

> --On Wednesday, July 17, 2013 11:32 AM +0200 Marco Schirrmeister <marco@schirrmeister.net> wrote:
> 
>> 
>> On Jul 17, 2013, at 1:08 AM, Howard Chu <hyc@symas.com> wrote:
>> 
>>> Marco Schirrmeister wrote:
>>>> Hi,
>>>> 
>>>> I have a problem with mdb and modify operations on very large groups.
>>>> Specifically deleting members from those groups. Removing 10 members
>>>> from a group with 25000 members takes 23 seconds. Which also means, all
>>>> other clients that want to do something hang. Deleting a user from
>>>> multiple big groups takes minutes before it finishes. Adding members to
>>>> a large group is quick though.
>>>> 
>>>> When this delete is running, the cpu goes also up to 100%.
>>>> 
>>>> It looks like it has to do with the index that I have on uniqueMember.
>>>> If I remove the index on uniqueMember, the delete of members in big
>>>> groups is fast.
>>>> 
>>>> System details are
>>>> CentOS 6 64bit
>>>> OpenLDAP 2.4.35
>>>> slapd.conf below
>>>> 
>>>> Is this something normal/exptected or is it maybe a bug?
>>> 
>>> Read slapd.conf(5) manpage, sortvals keyword.
>> 
>> Thanks for the hint Howard.
>> Deleting members from a big group on the test server is now fast with
>> sortvals.
>> 
>> Adding of members is a very little slower (20-30ms) compared to the
>> adding without sortvals. I will see how it goes on the production
>> environment with the real workload.
> 
> Personally, I prefer dynamic groups.  You may wish to investigate those as well.

We are already in the process of this. But various code needs to be updated which maintains right now the groups.

Those large groups are also relative new that we have them. That's why we did not notice the problem (or wrong config) earlier.


Marco