Glover, Matthew wrote:
> I'm having a performance problem with searches on a branch and I'm hoping 
> someone can explain it.
> 
> A search for "(uid=12345)" on basedn "dc=example,dc=com" with a subtree scope 
> returns much more quickly than the same filter and scope on basedn
> "ou=People,dc=example,dc=com".

Sounds vaguely like ITS#7473 but that was fixed 5 years ago. Maybe your index 
is not configured?
> 
> To confirm this wasn't just a problem with my schema or configuration, I 
> loaded Ubuntu 18 (slapd 2.4.45+dfsg-1ubuntu1), used ldctl to generate 100,000
> inetOrgPerson records with uids from 00000 to 99999, loaded them in with 
> ldapadd, then used ldctl to test performance of searches:
> 
> Both tests were scope subtree, 20 seconds, hitting the test server as fast as 
> possible with randomly generated filters of "(uid=<random uid from 00000 to 
> 99999>)".
> basedn: dc=example,dc=com - 5455.30/sec - total: 109106 successful searches
> basedn: ou=People,dc=example,dc=com - 198.80/sec - total: 3976 successful 
> searches
> 
> Also, while testing against ou=People, the CPU load from slaps went through 
> the roof.  It feels rather like the index isn’t being used when the base 
> isn’t the
> root.  
> 
> I can provide the ldif of my test users and the parameters I used for ldctl 
> tests if desired.
> 
> 
> Thanks for any help you can offer,
> Matthew


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  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/

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