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From Lance Norskog <goks...@gmail.com>
Subject Re: Does specifying a smaller number of rows in search improve efficiency?
Date Thu, 21 Jan 2010 04:24:11 GMT
The data in stored fields that is fetched back is in different files
than the index data. So, when you ask for documents you are asking for
more disk i/o. The different fields are in different places on the
disk, so if you request only 1 out of 20 fields, the query will be
slightly faster. I once measured a 5% improvement in "1 field v.s. all
fields" but it's different for each index.

On Tue, Jan 19, 2010 at 3:44 AM, Grant Ingersoll <gsingers@apache.org> wrote:
>
> On Jan 18, 2010, at 11:17 AM, Yonik Seeley wrote:
>
>> On Mon, Jan 18, 2010 at 8:57 AM, Erick Erickson <erickerickson@gmail.com> wrote:
>>> Nope. The problem is that SOLR needs to create a ranked
>>> list. It has to search the entire corpus every time. There's
>>> always the possibility that the very last document examined
>>> would rank highest.
>>
>> There's also the priority queue used to collect the top matches that
>> needs to remain ordered.
>> Finding and scoring matching documents will normally dominate the
>> time, but if "N" becomes large (for collecting the top N matches), the
>> priority queue operations can become significant.
>
>
> See also https://issues.apache.org/jira/browse/SOLR-1726
>
> --------------------------
> Grant Ingersoll
> http://www.lucidimagination.com/
>
> Search the Lucene ecosystem using Solr/Lucene: http://www.lucidimagination.com/search
>
>



-- 
Lance Norskog
goksron@gmail.com

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