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From "Alex Karasulu" <akaras...@apache.org>
Subject Re: [ApacheDS] OR expression optimizations for Cursors and Evaluators
Date Thu, 27 Mar 2008 17:43:40 GMT
As I try to implement this I am beginning to see some serious issues with
the heuristic cited in this document.  The problem is sub-expression Cursors
in the OR Cursor can be on anything: a logical expression or on an attribute
Index for a simple leaf assertion.  When on an index, the results of the
Cursor are sorted by the key (value of the attribute) of the index and not
by ID.

The children of an OR Cursor can be on any attribute index.  This means the
Cursor results are not sorted by id as supposed by this heuristic.  Instead
they're sorted by attribute value.  This will lead to inconsistent results.

This heuristic is useless :(.  What a waste!  It would have been so
efficient.

Alex

On Thu, Mar 27, 2008 at 11:31 AM, Alex Karasulu <akarasulu@apache.org>
wrote:

> On Thu, Mar 27, 2008 at 3:59 AM, Emmanuel Lecharny <elecharny@gmail.com>
> wrote:
>
> > Hi Alex,
> >
> > Alex Karasulu wrote:
> > >
> > >
> > http://cwiki.apache.org/confluence/display/DIRxSRVx11/Cursors+and+Evaluators+on+Logical+Disjunctions
> >
> > I have read and checked the wiki page. I have nothing to add
> >
>
> Cool.  BTW I documented that sweet optimization you cited a week ago for
> rapid shorting of child expression evaluations.  I think this will be a
> significant optimization.
>
>
> > FYI, I'm slowly coming back but I still have some side things to deal
> > with.
>
>
> No worries.  BTW I'm thinking we can just do a quick ADS release with only
> the top handful of issues that are critical for this 1.5.2 feature
> release.
>
> Alex
>
>

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