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Re: Should Berkeley DB backends be reloaded occasionally?



On 06/01/2011 08:30 AM, Howard Chu wrote:
> Ondrej Kuznik wrote:
>> On 06/01/2011 12:12 AM, Howard Chu wrote:
>>> Mark wrote:
>>>> Back in the days of OpenLDAP 2.1 with Berkeley DB 4.1.25.3 we used to have to
>>>> 'reload' out backend database occasionally as non-indexed reads would get
>>>> slower and slower over time. The 'reload' entailed:
>>>>
>>>>    * stop slapd
>>>>    * slapcat the contents to an .ldif file
>>>>    * remove the database files
>>>>    * slapadd the .ldif file to create a new, fresh db instance
>>>>    * start slapd
>>>>
>>>>
>>>> Then our performance problems went away. Re-indexing didn't do the trick.
>>>>
>>>> Is such occasional re-building of the backend database recommended in OpenLDAP
>>>> 2.4.25 with Berkeley DB 4.8.30?
>>>
>>> Try it and see.
>>>
>>> Non-indexed reads are always going to be pretty slow, regardless.
>>
>> Might be that he's hitting this?
>> http://www.openldap.org/lists/openldap-technical/201011/msg00146.html
> 
> Clearly not, since that message is all about indexing, and he's talking about 
> non-indexed reads.

As far as I have understood that message of yours, the "index" is a list
of all the entries in the subtree. That should have nothing to do with
attribute indexing. Might be that I completely misunderstood that issue
but looking at the testbed you attached in
http://www.openldap.org/lists/openldap-technical/201011/msg00148.html I
see no filter passed to ldapsearch so no attribute indexes should apply.

Please do correct me if I'm wrong in any of the above as that implies I
have misunderstood a part of how OpenLDAP works thus need to revisit
relevant documentation and play with it more to prevent it biting me
later on.

-- 
Ondrej Kuznik

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