Hibernate Search and Nearest Neighbor

Chris S · **Joined:** Wed Sep 16, 2015 10:30 am **Posts:** 2

I'm currently investigating using Hibernate Search (spatial) for some queries. I've seen a ton of code/references to "distance from" - but one of my requirements is a "Nearest Neighbor" search. Basically, I need a "what is the closest 10 stores from my current location" type query. I've not seen this referenced from my google-foo - so I thought I post it here. Is this type of query possible with hibernate search or do I need to leverage Oracle's spatial functionality?

Thanks for any info!

Chris

Gunnar · **Joined:** Sat Jan 24, 2009 12:46 pm **Posts:** 388

It's doable by setting the max results number and ordering the results by distance. E.g. like so:

Code:

final QueryBuilder builder = fullTextSession.getSearchFactory()
    .buildQueryBuilder().forEntity( Store.class ).get();

org.apache.lucene.search.Query luceneQuery = builder.spatial().onField( "location" )
    .within( 20.0, Unit.KM ).ofLatitude( centerLatitude ).andLongitude( centerLongitude )
    .createQuery();

org.hibernate.Query hibQuery = fullTextSession.createFullTextQuery( luceneQuery, Store.class )
    .setMaxResults( 10 )
    .setSort( new Sort( new DistanceSortField(centerLatitude, centerLongitude, "location") ) );

List results = hibQuery.list();

You still need to set a radius via within(). Either set it to a sufficiently large value to consider all locations or incrementally increase it in case you don't get back enough results.

Hth,

--Gunnar

Chris S · **Joined:** Wed Sep 16, 2015 10:30 am **Posts:** 2

Thanks for the tip.

As a followup to that, any clue on performance differences doing "distance within" and your trick for "nearest neighbor" as compared to using Oracle's native geospatial functions (Locator)? Obviously this is largely dependent upon the data - but I'm wondering if there are any metrics on which implementation, in general, would perform these functions faster? The nice thing, I can use both and test the implementations side-by-side. But the advantage of using the Search is that it's database agnostic.

Cheers!

Chris

Gunnar · **Joined:** Sat Jan 24, 2009 12:46 pm **Posts:** 388

Hi,

Sorry, I don't have any performance comparison at my hand. If you got something, I'd be very interested to know. Btw. you also may be interested in the "Hibernate Spatial" feature which is part of Hibernate ORM 5, I think it works with Oracle's spatial functionality, too. This used to be a separate project (hibernatespatial.org) but is now included in the ORM code base.

--Gunnar