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RE: [grouper-users] Efficient loader rollup groups for leaf groups?

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  • From: Chris Hyzer <>
  • To: "" <>, Grouper Users Mailing List <>
  • Subject: RE: [grouper-users] Efficient loader rollup groups for leaf groups?
  • Date: Wed, 20 May 2009 10:15:34 -0400
  • Accept-language: en-US
  • Acceptlanguage: en-US

What is the performance problem? The query against the grouper_groups_v? Or
the number of rows returned? Is it slow only on the first run, or also on
subsequent runs (I mention since the loader takes time to insert memberships
the first time, and when things don’t change much, it is much quicker)?

The grouper_groups_v is a little heavy, if that is the bottleneck, you might
consider making your own groups view which has only what you need in it.
Granted, when you upgrade grouper you will have to look at it and perhaps
adjust (I don’t think this is a big deal, but up to you :) ).

Let me know

> -----Original Message-----
> From: Loris Bennett
> [mailto:]
> Sent: Wednesday, May 20, 2009 7:41 AM
> To: Grouper Users Mailing List
> Subject: [grouper-users] Efficient loader rollup groups for leaf
> groups?
> Hi,
> For an org structure with a an automatically generated group ('%:auto')
> at each node in the tree we use grouperloader to create roll-up groups
> of all the auto groups one level below using this slightly modified
> suggestion Chris made:
> select
> || ':all' as group_name,
> ggv.group_id as subject_id,
> as sub_group_name
> from
> grouper_stems gs,
> grouper_groups_v ggv
> where
> like 'sources:employees:'
> and
> similar to || ':[^:]*:auto'
> and
> exists (select 1 from grouper_stems gs2 where like
>|| ':%')
> (actually this turns out to be a bit slow when there are a lot of
> groups, so we in fact now use a different query which makes use of the
> fact that grouper_stems contains information about the parent stem of
> each entry).
> I now have a similar, but slightly different problem. In another tree I
> have the students sorted according to the degree they are studying.
> That
> is I have groups like:
> physics:physics:bsc:2008:major:auto
> that is :
> department, course name , degree type, version of course,
> major/minor
> This tree contains auto-groups only in leaf nodes. I want to create
> roll-up groups which contain all the "auto" groups below them in the
> hierarchy.
> I can solve this using an approach like the one above. I.e. I could
> select
> for each stem all the auto groups for which the stem is a substring of
> the group name. However, this is going to run into similar performance
> issues to those of the statement above.
> Can anyone think of a better approach?
> As a workaround I could generate the "all" groups when I create the
> stem
> hierarchy. Then I could just select the "all" groups of the child nodes
> as members of the "all" group in the current node. This would be
> analogous to the first scenario I described.
> Cheers
> Loris
> --
> Dr. Loris Bennett
> Computer Centre
> Freie Universität Berlin
> Berlin, Germany

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