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Re: [grouper-dev] Performance of Group Searches

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  • From: "Michael R. Gettes" <>
  • To: Grouper Dev <>
  • Subject: Re: [grouper-dev] Performance of Group Searches
  • Date: Fri, 19 Oct 2007 15:12:51 -0400

On Oct 19, 2007, at 15:05, Shilen Patel wrote:
Tom Barton wrote:
I can't think of a downside to pre-fetching group attributes.
Beyond the space they take up, compared to a list of UUIDs. So this is a clear space/time trade-off. Could you arrange to observe jvm memory usage with a search that nets an even larger number of groups, try to get a sense of how much of a trade-off?
The space can definitely add up as the number of groups returned increases. I performed a query for all of our approximately 100,000 course groups. The attributes are stored in HashMaps and each HashMap has the 4 default key-value pairs for the names and extensions of the group. We don't have any additional attributes for these course groups. Anyways, the 100,000 HashMaps take up about 22MB of space.

that's not much space!

Since Michael brought up the comparison with LDAP, I just had a thought. When you perform an LDAP search you can provide a list of attributes you want returned. Has there been a consideration of doing something similar with Group searches? Just a thought....

This was part of what i was getting at with windowing on the call the other day.
Only get what you need.

I also find it interesting that when I do the search that gives 100,000 results, it takes 107 seconds when I use the default TTL and memory values in the ehcache.xml file used by hibernate. However, if I set the TTL and memory values to something that would not be reached, the query takes 76 seconds. 31 seconds are spent just flushing the cache.

Again, more lessons from the LDAP world - this is what LDAP tuning is all about - getting
the caching configured properly. When you do - LDAP is blazingly fast!


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