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From Ted Zlatanov <...@lifelogs.com>
Subject Re: bitmap slices
Date Wed, 03 Feb 2010 17:00:19 GMT
On Mon, 1 Feb 2010 11:14:12 -0600 Jonathan Ellis <jbellis@gmail.com> wrote: 

JE> 2010/2/1 Ted Zlatanov <tzz@lifelogs.com>:
>> On Mon, 1 Feb 2010 10:41:28 -0600 Jonathan Ellis <jbellis@gmail.com> wrote:
>> 
JE> I don't think this is very useful for column names.  I could see it
JE> being useful for values but if we're going to add predicate queries
JE> then I'd rather do something more general.
>> 
>> Do you have any ideas?

JE> Not really, no.  I think we're best served developing feature X by
JE> starting with problems that can only be solved with X and working from
JE> there.  Going the other direction is asking for trouble.

I looked at the filters, e.g. o.a.c.db.filter.SliceQueryFilter, and it
seems like one place to put predicate logic is in that hierarchy.
Perhaps there can be a PredicateQueryFilter.  Some thought has
apparently already gone into flexible filters at the storage level.  I
hope something happens in this direction but I won't push for it
further since it's not what I need.

The attached patch is how I propose to do bitmasks inside the
SlicePredicate.  As you suggested, it solves the specific problem.  It's
pretty simple and carries no performance penalty if bitmasks are not
used.  It's untested, intended to show the interface and approach I am
proposing.  I didn't open an issue since it's unclear that this is the
way to go.

Thanks
Ted


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