Re: ldap query performance issue

--On Thursday, May 23, 2013 4:40 PM +0000 Chris Card <ctcard(a)hotmail.com&gt; wrote: > Hi all, > > I have an openldap directory with about 7 million DNs, running openldap > 2.4.31 with a BDB backend (4.6.21), running on CentOS 6.3. > > The structure of the directory is like this, with suffix dc=x,dc=y > > dc=x,dc=y > account=a,dc=x,dc=y > mail=m,account=a,dc=x,dc=y // Users > .... > licenceId=l,account=a,dc=x,dc=y // Licences, > objectclass=licence .... > group=g,account=a,dc=x,dc=y // Groups > .... > // etc. > > account=b,dc=x,dc=y > .... > > Most of the DNs in the directory are users or groups, and the number of > licences is small (<10) for each account. > > If I do a query with basedn account=a,dc=x,dc=y and filter > (objectclass=licence) I see wildly different performance, depending on > how many users are under account a. For an account with ~30000 users the > query takes 2 seconds at most, but for an account with ~60000 users the > query takes 1 minute. > > It only appears to be when I filter on objectclass=licence that I see > that behaviour. If I filter on a different objectclass which matches a > similar number of objects to the objectclass=licence filter, the > performance doesn't seem to depend on the number of users. > > There is an index on objectclass (of course), but the behaviour I'm > seeing seems to indicate that for this query, at some point slapd stops > using the index and just scans all the objects under the account. > > Any ideas? Increase the IDL range. This is how I do it: --- openldap-2.4.35/servers/slapd/back-bdb/idl.h.orig 2011-02-17 16:32:02.598593211 -0800 +++ openldap-2.4.35/servers/slapd/back-bdb/idl.h 2011-02-17 16:32:08.937757993 -0800 @@ -20,7 +20,7 @@ /* IDL sizes - likely should be even bigger * limiting factors: sizeof(ID), thread stack size */ -#define BDB_IDL_LOGN 16 /* DB_SIZE is 2^16, UM_SIZE is 2^17 */ +#define BDB_IDL_LOGN 17 /* DB_SIZE is 2^16, UM_SIZE is 2^17 */ #define BDB_IDL_DB_SIZE (1<<BDB_IDL_LOGN) #define BDB_IDL_UM_SIZE (1<<(BDB_IDL_LOGN+1)) #define BDB_IDL_UM_SIZEOF (BDB_IDL_UM_SIZE * sizeof(ID)) --Quanah -- Quanah Gibson-Mount Sr. Member of Technical Staff Zimbra, Inc A Division of VMware, Inc. -------------------- Zimbra :: the leader in open source messaging and collaboration