Re: Retrieving more results after LDAP_SIZELIMIT_EXCEEDED

[Pierangelo Masarati <ando@sys-net.it>]

Jiang, David wrote:

> Hi,
>  
> We are trying to optimize the performance of our slapd server and 
> client. During the course of profiling, we noticed that changing the 
> sizelimit parameter in the slapd.conf file increases the performance 
> considerably on the server. However, this results in receiving an 
> error code of LDAP_SIZELIMIT_EXCEEDED when a query returns more 
> results than the sizelimit. Is it possible to retrieve more results 
> after receiving an LDAP_SIZELIMIT_EXCEEDED? We have yet to find sample 
> code that does this. Or would it be better to keep a higher sizelimit 
> parameter in the slapd.conf file but specify a sizelimit of 1 as 
> a parameter to ldap_search_s when it is known that only 1 entry should 
> be returned? Thanks,

Changing the sizelimit definitely reduces server load provided the limit 
is hit by those queries that return more than sizelimit results, this is 
plain obvious.  The drawback is that those queries actually do not 
receive all the results they expected, and this is plain obvious as 
well.  If you use latest 2.2 you can:
1) set different sizelimits for different users/groups, so that those 
who are authorized can have higher (even unlimited) size limits, and 
those who are not have lower (even search disabled) size limits (note 
that disabling search has nearly the same effect as protecting behind 
ACLs, from a client's perspective; but from a server's perspective it 
saves the need to search the database and test filter and ACLs).  You 
can also use paged results control (available with bdb in latest 2.2) to 
set, say, a sizelimit for plain searches but no limits on the total size 
of a paged results search.
Setting a sizelimit of 1 on searches that exactly return 1 entry has no 
effects on performances.

p.





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