Norbert wrote: > Hi, > > Used version 2.5.19.1 (ltb) > > We have a LDAP with about 4.6 million entries and an indexed attribute which > occurs around 3.9 million times. We typicall filter for that attribute with a > specific value (eq). Which is typicall very fast and no problems. As soon as > the same value used twice the execution time for that filter is becoming > really > slow even when additional criteria of the filter limits the result to exact 1 > entry. Search time is at ~5% for single entry results compared to potential 2 > entry results. > > Some more details how this was determined: > 1) enable "stats" logging on production server for 5 minutes. > 2) collect the slowest ~1200 from several thousand searches within the 5 > minutes from the log > 3) create a separate ldap server with exact same data and configuration > (imported with slapadd) > 4) use a script running locally on the extra server which executes the 1200 > filters one after the other and measure complete execution time of script > > With production data I measure around 11s for the ~1200 searches. For all > these searches one attribute in the filter could have 2 hits, but it is > actually > limited to 1 hit because of following filter > "(&(objectClass=value)(almost_uniqe_attr=value)(another_attr=*))" Means > searching with only "almost_uniqe_attr=value" as filter it would return 2 > results, but > objectClass and another_attr limit it to exact 1 entry. > > When I now remove the second entry from the ldap server for these exact ~1200 > filters the script run time will be ~0.5s . > If re-add those ~1200 entries the runtime will be around 5s (and with a > complete recreate of the db it will be 11s again.) > > Limiting the search scope by using a more specific base dn for the search > does not change anything in regards to the execution time. > > So the question is: 1) can I change anything on the server side to speed up > the execution time of these searches?
How common is 'another_attr'? Is there a presence index on it? > > Regards, > Norbert > -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
