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From Alex Karasulu <aok...@bellsouth.net>
Subject Re: Various questions
Date Tue, 06 Jun 2006 13:33:25 GMT
Quanah Gibson-Mount wrote:

>
>
> --On Tuesday, June 06, 2006 12:50 AM -0400 "Noel J. Bergman"
> <noel@devtech.com> wrote:
>
>> Quanah Gibson-Mount wrote:
>>
>>> I think the concept of applying all indexing to attributes is in itself
>>> broken.
>>
>>
>> So is your suggestion that the option be made available, but that by
>> indexing selectively, Alex's concerns can be effectively addressed?  Do
>> you have any suggestions as to how that might be provided without losing
>> ease-of-use for the most common cases?
>
>
> Well, in OpenLDAP, the way ease of use is met is by users being able
> to define a default index type or types.  That way, they can specify
> the default set, and then just use index <attribute>, similar to what
> is being done in Apache DS.
>
> I think it is important to allow specification of what indices to use
> for a given attribute for a few reasons.  One, that you can use it to
> actually make some searches slow enough to hinder efforts (like we
> have a spam troller routinely trying to get data from our sources that
> is fairly obnoxious), another is that the more indices you have on an
> attribute, the larger the total database is, and the longer it takes
> to load.  This of course depends on part in the OS/Cpu used as well. 
> For example, I currently index 90 attributes in my database to varying
> degrees (most are eq, which is a fairly minimal index).  

Note that ApacheDS indices are very similar to OpenLDAP equality indices
with some minor differences for handling substring matching.  The cost
is about the same as an eq index.  So you get sub, eq, and existence for
the price of eq.

> On my Solaris sparc systems, it takes 2.5ish hours to load the database.  

What kind of sparc is that?  I have a blade 2000 here if you want to try
a current machine benchmark.  I could create an account for you to
test.  Just let me know.

> On my new AMD systems that'll be replacing the Sun Sparc boxes, it
> takes all of 14.5 minutes.  However, if all 90 of those attributes
> were getting indexed pres,eq,sub, the amount of time to load would
> increase significantly.
>
> Currently, my indices take up 1.1GB of disk space in OpenLDAP (I'm not
> sure how that exactly map out in Apache DS).  My database entry file
> takes 2.7GB.  So my indices are approximately 1/3 of my database size.

Yeah the cost of disk space is just about the same but that's the least
of our worries.  Disk is cheap as Emmanuel stated.

Alex


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