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From Eran Sevi <erans...@gmail.com>
Subject Re: Efficient filtering advise
Date Mon, 23 Nov 2009 13:12:54 GMT
Erick,

Maybe I didn't make myself clear enough.
I'm talking about high level filters used when searching.

I construct a very big BooleanQuery and add 50K clauses to it (I removed the
limit on max clauses).
Each clause is a TermQuery on the same field.
I don't know the internal doc ids that I want. I only know the value stored
in the field. this value is an external key of the document and guaranteed
to be unique.

I pass this query to QueryFilter and run a search using search
(query,filter,collector) (reminder: i'm using ver 2.4)

If I missed some other magic construction method to achieve the same goal
then it would be great.

Thanks for you help so far,
Eran.

On Mon, Nov 23, 2009 at 2:55 PM, Erick Erickson <erickerickson@gmail.com>wrote:

> Now I'm really confused, which usually means I'm making some
> assumptions that aren't true. So here they are...
>
> 1> You're talking about Filters that contain BitSets, right? Not some other
>     kind of filter.
> 2> When you create your 10-50K filters, you wind up with a single filter
>     by combining them all with one of the BitSet operators, right? And
>     that *single* filter is the one you send to your query...
>
> If I'm off base here, could you post a reasonable extract of your filter
> construction code, and how you use them to search? Because I don't
> think we're all talking about the same thing here.....
>
> HTH
> Erick@ThisMakesNoSenseToMe<G>...
>
> On Mon, Nov 23, 2009 at 5:18 AM, Eran Sevi <eransevi@gmail.com> wrote:
>
> > After commenting out the collector logic, the time is still more or less
> > the
> > same.
> > Anyway, since without the filter collecting the documents is very fast
> it's
> > probably something with the filter itself.
> >
> > I don't know how the filter (or boolean query) work internally but
> probably
> > for 10K or 50K clauses, it does something that takes a lot of time. It
> > might
> > be because of the inner data structures that are used or maybe just the
> > iteration on so many terms takes time.
> >
> > I'll continue to try and pinpoint the exact bottleneck postion, or maybe
> > using the new filters in 2.9.1 might help.
> >
> > On Sun, Nov 22, 2009 at 8:36 PM, Erick Erickson <erickerickson@gmail.com
> > >wrote:
> >
> > > Hmmm, could you show us what you do in your collector? Because
> > > one of the gotchas about a collector is loading the documents in
> > > the inner loop. Quick test: comment out whatever you're doing in
> > > the underlying collector loop, and see if there's *any* noticeable
> > > difference in speed. That'll tell you whether your problems
> > > arise from the filter construction/search or what you're doing
> > > in the collector....
> > >
> > > Best
> > > Erick
> > >
> > > On Sun, Nov 22, 2009 at 11:41 AM, Eran Sevi <eransevi@gmail.com>
> wrote:
> > >
> > > > I think it shouldn't take X5 times longer since the number of results
> > is
> > > > only about X2 times larger (and much smaller than the number of terms
> > in
> > > > the
> > > > filter), but maybe I'm wrong here since I'm not familiar with the
> > filter
> > > > internals.
> > > >
> > > > Unfortunately, the time to construct the filter is mere milliseconds.
> > > > almost all of the time (~5secs) are spent in the search method.
> > > > I'm using a collector to retrieve all the results (and fetch a value
> > for
> > > > some fields) but without the filter this also takes less then a
> second
> > > for
> > > > the same number of results.
> > > >
> > > > On Sun, Nov 22, 2009 at 5:57 PM, Erick Erickson <
> > erickerickson@gmail.com
> > > > >wrote:
> > > >
> > > > > Hmmm, I'm not very clear here. Are you saying that you effectively
> > > > > form 10-50K filters and OR them all together? That would be
> > > > > consistent with the 50K case taking approx. 5X a long as the 10K
> > > > > case.....
> > > > >
> > > > > Do you know where in your code the time is being spent? That'd
> > > > > be a big help in suggesting alternatives. If I'm on the right
> track,
> > > > > I'd expect the time to be spent assembling the filters.....
> > > > >
> > > > > Not much help here, but I'm having trouble wrapping my head
> > > > > around this...
> > > > >
> > > > > Best
> > > > > Erick
> > > > >
> > > > > On Sun, Nov 22, 2009 at 9:48 AM, Eran Sevi <eransevi@gmail.com>
> > wrote:
> > > > >
> > > > > > Hi,
> > > > > >
> > > > > > I have a need to filter my queries using a rather large subset
of
> > > terms
> > > > > > (can
> > > > > > be 10K or even 50K).
> > > > > > All these terms are sure to exist in the index so the number
of
> > > results
> > > > > can
> > > > > > be about the same number of terms in the filter.
> > > > > > The terms are numbers but are not subsequent and are from a
large
> > set
> > > > of
> > > > > > possible values (so range queries are probably not good for
me).
> > > > > > The index itself is about 1M docs and running even a simple
query
> > > with
> > > > > such
> > > > > > a large filter takes a lot of time even if the number of results
> is
> > > > only
> > > > > a
> > > > > > few hundred docs.
> > > > > > It seems like the speed is affected by the length of the filter
> > even
> > > if
> > > > > the
> > > > > > number of results remains more or less the same, which is logical
> > but
> > > > not
> > > > > > by
> > > > > > such a large loss of performance as I'm experiencing (running
the
> > > query
> > > > > > with
> > > > > > a 10K terms filter takes an average of 1s 187ms with 600 results
> > > while
> > > > > > running it with a 50K terms filter takes an average of 5s 207ms
> > with
> > > > 1000
> > > > > > results).
> > > > > >
> > > > > > Currently I'm using a QueryFilter with a boolean query in which
I
> > > "OR"
> > > > > the
> > > > > > different terms together.
> > > > > > I also can't use a cached filter efficiently since the terms
to
> > > filter
> > > > on
> > > > > > change almost every query.
> > > > > >
> > > > > > I was wondering if there's a better way to filter my queries
so
> > they
> > > > > won't
> > > > > > take a few seconds to run?
> > > > > >
> > > > > > Thanks in advance for any advise,
> > > > > > Eran.
> > > > > >
> > > > >
> > > >
> > >
> >
>

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