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Re: [grouper-dev] Re: [grouper-users] Dynamics groups in grouper

Chronological Thread 
  • From: Tom Barton <>
  • To:
  • Cc: "GW Brown, Information Systems and Computing" <>,
  • Subject: Re: [grouper-dev] Re: [grouper-users] Dynamics groups in grouper
  • Date: Wed, 20 Feb 2008 13:55:32 -0600

Arnaud Deman wrote:
How many dynamic groups are you likely to need? Do they have to be fully enumerated i.e. will you be expecting to list these memberships or just test whether someone is a member?
A lot ! ;) We don't know currently exactly how many but it is possible that we have to manage several thoushands (say between 3000 and 5000). And of course we would like to enumerate them ! We can't do that with the PAGS groups and it was also one of our motivation to extends Grouper for this purpose.

This is where dynamic and static groups mix about as well as oil and water. You can't know that a subject is not a member of a dynamic group until you evaluate the dynamic group membership filter on that subject. So, to enumerate a subject's memberships will require that all dynamic group filters are evaluated. If you have 5000 of those, they'll all need to be evaluated every time you need to enumerate memberships.

This type of issue is what led us early on to maintain "flattened" group membership information in grouper, ie, compute the indirect membership effects of subgroups and composite groups as they are created. That enables us to quickly enumerate memberships on demand. I suspect that only a "pre-computed" approach to dynamic group membership can scale to more than a handful of dynamic groups.

Something must update the attributes in the LDAP directory (or many LDAP directories?) that appear in the filters defining your dynamic groups. Can this LDAP updating process be used to trigger updating of the flattened membership of dynamically-defined groups?

fn:Tom Barton
org:University of Chicago;Networking Services & Information Technology
adr;dom:1155 E. 60th St.;;Rm 309, 1155 Bldg;Chicago;IL;60637
title:Sr. Director - Integration
tel;work:+1 773 834 1700

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