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From "Pieter Berkel" <pieter.ber...@gmail.com>
Subject Re: retrieving range of fields for the results
Date Wed, 08 Aug 2007 12:44:07 GMT
You could probably achieve this using faceting, however it would not be a
very efficient solution (although your multi-query idea isn't very efficient
either).  Since facets return result sets in field sort order if you specify
facet.sort=false (setting that to try sorts the field by count), so you
could use query parameters like the following:

facet=true&facet.sort=false&facet.missing=false&facet.limit=-1&facet.mincount=1&facet.field=price&facet.field=publish_date

And simply extract the first and last values of the facet which should give
you the minumum and maximum values.

I'm pretty certain there is currently no option to simply return the minimum
/ maximum facet values but it might be and idea for a future enhancement.

cheers,
Piete


On 08/08/2007, Yu-Hui Jin <yuhui.jin@gmail.com> wrote:
>
> Piete,
>
> Thanks for the pointers and detailed info. Actually I'm aware of the
> faceting feature. Faceting provides the ability to categorize the results
> with the count for each category. However,I don't think that solves my
> problem.
>
> Let me give a more detailed example for my requirement:
>
> Let's say we indexed 100 documents representing books with the following
> fields:
>
> (id, title, price, publish_date, description)
>
> Suppose a query "title:art history"  ( We are using Solr 1.1, will use
> "sort" param when migrating to 1.2.) which returns 5 results:
>
> (25, "The History of Art", 56.0, 07-10-1995, "blah blah blah")
> (54, "Art History", 38.0, 02-13-1997, "blah blah blah")
> (13, "Art", 45.0, 10-05-1980, "blah blah blah")
> (3, "The Art of War", 40.0, 12-12-2000, "blah blah blah")
> (38, "History of Everything", 15.0, 12-31-2001, "blah blah blah")
>
> Now my requirement is that along with these five results, I also want Solr
> to return the following:
>
> The [min, max] range for the 'price' field, in this case:  [15.0, 56.0]
> The [min, max] range for the 'publish_date' field, in this case:
> [10-05-1980, 12-31-2001]
>
> I don't think faceting would give me these ranges, it can only give me
> counts of ranges/values, for example if I specified facet.query of
> different
> price ranges.
>
> So all I can think of now is that I have to
> 1) make 'price' and 'publish_date' sortable in the schema;
> 2) after each query (which returns non-empty result set), issue two more
> queries, one adding sort on 'price' to the original query, the other
> adding
> sort on 'publish_date'. (the sort order doesn't matter).
> 3) get the respective min, max values of these two fields from the first
> and
> last document returned for each of the two subsequent queries.
>
> Is there any better way to accomplish this?
>
>
> Thanks,
>
> -Hui
>
>
>
> On 8/7/07, Pieter Berkel <pieter.berkel@gmail.com> wrote:
> >
> > The functionality you are describing is called "Faceting" in Solr and
> can
> > be
> > achieved with a single query, take a look at the following wiki pages
> for
> > more info:
> >
> > http://wiki.apache.org/solr/SolrFacetingOverview
> > http://wiki.apache.org/solr/SimpleFacetParameters
> >
> > In regards to faceting date fields such as publish_date, take a look at
> > https://issues.apache.org/jira/browse/SOLR-258 which was recently
> commited
> > to the svn trunk (although not much documentation on that yet).
> >
> > Just a note about your query, specifying the sort order in the q
> parameter
> > is depricated syntax, you are better to use the sort parameter for that,
> > again refer to the wiki:
> >
> > http://wiki.apache.org/solr/CommonQueryParameters
> >
> > Hope this helps,
> > Piete
> >
> >
> > On 07/08/07, Yu-Hui Jin <yuhui.jin@gmail.com> wrote:
> > >
> > > Hi, there,
> > >
> > > We used Solr to index a set of documents and provide free-text search
> > > functionality with sorting options on a number of fields. We have a
> > > requirement that along with each search result we want to obtain the
> > > ranges
> > > of a few fields for the resulting documents. Here's an example:
> > >
> > > Let's say we indexed documents representing books with the following
> > > fields:
> > >
> > > title, price, publish_date, description
> > >
> > > All of these fields are stored in the index (that can be returned);
> and
> > > "price" and "publish_date" are sortable as well.
> > >
> > > Now suppose we post a query for example "title:art history;price asc",
> > we
> > > want to the following results:
> > >
> > > 1. the documents satisfying the query (which by default are returned
> by
> > > solr);
> > > 2. the range of the price field of the results.
> > > 3. the range of the publish_date of the results.
> > >
> > > My question is -- can solr return all of the above data within one
> > > response?  If not, all I can think of is to issue one more query that
> > > "title:art history;publish_date asc" (or desc) so that I can use the
> > first
> > > and last result of this query to get the range for publish_date.  (Due
> > to
> > > the original query already asking to sort by price, we are lucky in
> this
> > > case that we don't have to issue another query to get the range of
> > price.
> > > But then this does not apply in the general case.)
> > >
> > > Any idea is appreciated!
> > >
> > > --
> > > Regards,
> > >
> > > -Hui
> > >
> >
>
>
>
> --
> Regards,
>
> -Hui
>

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