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From Mark Miller <>
Subject Re: RangeFilter performance problem using MultiReader
Date Fri, 10 Apr 2009 19:00:19 GMT
Michael McCandless wrote:
> On Fri, Apr 10, 2009 at 2:32 PM, Mark Miller <> wrote:
>> I had thought we would also see the advantage with multi-term queries - you
>> rewrite against each segment and avoid extra seeks (though not nearly as
>> many as when enumerating every term). As Mike pointed out to me back when
>> though : we still rewrite against the multi-reader and so see no real
>> savings here. Unfortunately.
> But, RangeQuery.rewrite is simply enumerating terms, which I think is
> working "OK".
> It's enumerting terms, then seeking a sister TermDocs to each term,
> that tickles the over-seeking problem.  FieldCache does that, and
> RangeFilter on 2.4 does that, but RangeFilter (or RangeQuery with
> constant score mode) on 2.9 should not (they should do it per
> segment), which is why I'm baffled that Raf didn't see a speedup on
> upgrading.
> Mike
Ah, right - anything utilizing a filter will see the gain. It wouldn't 
be such a big gain unless there were a *lot* of matching terms though 
right? Fieldcache is so bad because its every term. A smaller percentage 
of terms for a field won't be nearly the problem.

- Mark

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