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From Michael McCandless <luc...@mikemccandless.com>
Subject Re: Reopening a Searcher for each request
Date Thu, 22 Apr 2010 11:11:55 GMT
It's the IndexReader that's costly to open/warm, so ideally it should
be opened once and shared.

The Searchers do very little on construction so re-creating per query
should be OK.

Mike

On Thu, Apr 22, 2010 at 6:38 AM, Samarendra Pratap <samarzone@gmail.com> wrote:
> Greetings to all.
>  I have read at so many places that we should not open a Searcher for each
> request for the sake of performance, but I have always been wondering
> whether it is actually Searcher or Reader?
>
>  I have a group of index amounting to 23G which actually contains of
> different index directories. The structure is something like following
>
> Main directory
> |
> |_________ country1
> |                     |___ country1-time1 (actual index)
> |                     |___ country1-time2 (actual index)
> |                     |___ country1-time3 (actual index)
> |
> |_________ country2
>                     |___ country2-time1 (actual index)
>                     |___ country2-time2 (actual index)
>                     |___ country2-time3 (actual index)
>
>  When application starts I open IndexReaders on all of actual index
> directories (country1-time1, country1-tim2, .... country2-time3) and keep
> them in a pool.
>
>  At the time of search, IndexSearchers are created by selecting the
> appropriate IndexReaders from the pool. These IndexSearchers in turn are
> used to create a ParallelMultiSearcher. Constructors of IndexSearcher and
> ParallelMultiSearcher are run for every request.
>
>  Now I believe that creating a pool of ParallelMultiSearcher itself is a
> good idea but* I wanted to know if reopening **IndexSearchers** will really
> degrade performance irrespective of **IndexReaders** being opened once*.
>
> In my performance tests (which may not be very comprehensive) I didn't find
> any noticeable difference.
>
> Please throw some light.
>
>
> --
> Regards,
> Samar
>

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