Re: 2.4.10 slow when deleting member from large group

[Andrew Findlay <andrew.findlay@skills-1st.co.uk>]

On Wed, Jun 25, 2008 at 09:11:49AM -0700, Howard Chu wrote:

> >I have a server with 20,000 account entries and one group that
> >has 10,000 members. Deleting members from that group is very slow
> >on OpenLDAP 2.4.10, though adding goes at a reasonable speed.
> 
> Try configuring sortvals - see slapd.conf(5).

That helps a lot, thanks. It reduces the delete time to under 0.5s.

Unfortunately it seems to introduce a bug. If I *just* add or delete a
value all is OK, but if I delete one value and add another in the same
LDAP operation the new value does not get indexed. The value is in the
entry, but it cannot be searched for. Further, it cannot be deleted
(as it is 'not there') yet it can be added again, leading to multiple
identical values in the entry!

This only happens on *large* groups where the value being added would
sort to the end of the list of values. I don't know how large the group
has to be: 3 is not enough, and 10,000 is. My test case has a group that
starts with 10,000 members inserted in numerical order:

dn: uniqueIdentifier=tenK,ou=groups,uniqueIdentifier=o_000000,dc=orgs,dc=dir,dc=example,dc=org
objectclass: myGroup
uniqueIdentifier: tenK
displayName: Managers group tenK
description: Sample group of managers
member: uniqueIdentifier=a_000000,ou=accounts,uniqueIdentifier=o_000003,dc=orgs,dc=dir,dc=example,dc=org
member: uniqueIdentifier=a_000001,ou=accounts,uniqueIdentifier=o_000000,dc=orgs,dc=dir,dc=example,dc=org
member: uniqueIdentifier=a_000002,ou=accounts,uniqueIdentifier=o_000004,dc=orgs,dc=dir,dc=example,dc=org
member: uniqueIdentifier=a_000003,ou=accounts,uniqueIdentifier=o_000003,dc=orgs,dc=dir,dc=example,dc=org

Deleting an entry from the middle of the list and adding one of the form:
uniqueIdentifier=a_999999,ou=accounts,uniqueIdentifier=o_000005,...
causes the problem, but if I add one like this it does not:
uniqueIdentifier=a_00500Z,ou=accounts,uniqueIdentifier=o_000005,...
(that would go near the middle of the list)

Andrew
-- 
-----------------------------------------------------------------------
|                 From Andrew Findlay, Skills 1st Ltd                 |
| Consultant in large-scale systems, networks, and directory services |
|     http://www.skills-1st.co.uk/                +44 1628 782565     |
-----------------------------------------------------------------------