search in ldap access log not fast enough?

[Zhang Weiwu <zhangweiwu@realss.com>]

Dear list

For some special reasons search for modification log is a frequent
operation here in our environment. Usually searching for modification
log takes 30 seconds or longer:

$ ldapsearch -x -D cn=admin,cn=accesslog -w -b cn=accesslog
reqDN=uid=Schleifring,ou=contacts,ou=china,dc=ahk,dc=de reqSession;

Compare to a typical ldap search that search for a contact person or
anyone who live in a state which usually return the result in less then
1 seconds.

30 second time is not acceptable consider the frequency such search is
being used. I think I have 'optimized' slapd.conf by using these lines:

# used for accesslog, realss
database bdb
# The base of your directory for database #2
suffix  "cn=accesslog"
rootdn  "cn=admin,cn=accesslog"
rootpw  ....
directory       "/var/lib/ldap-log"
index   reqDN,reqType eq

And I have also rebuilt index by using
$ slapindex -b cn=accesslog

Is this 30 second search time normal and how can I improve search speed?
Thanks a lot in advance!

The total amount of accesslog entry is about 658147

-- 
Zhang Weiwu
Real Softservice
http://www.realss.com
+86 592 2091112