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Posted to solr-commits@lucene.apache.org by Apache Wiki <wi...@apache.org> on 2010/10/21 20:04:57 UTC
[Solr Wiki] Update of "SpatialSearch" by GrantIngersoll
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The "SpatialSearch" page has been changed by GrantIngersoll.
http://wiki.apache.org/solr/SpatialSearch?action=diff&rev1=39&rev2=40
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<!> [[Solr4.0]]
+
= Spatial Search =
<<TableOfContents(3)>>
@@ -15, +16 @@
'''NOTE: Unless otherwise specified, all units of distance are kilometers and points are in degrees of latitude,longitude.'''
= QuickStart =
- If you haven't already, get a recent nightly build of [[Solr4.0]], start the example server and index the example data as shown in the [[http://lucene.apache.org/solr/tutorial.html|solr tutorial]]. With the Solr server running, you should be able to
+ If you haven't already, get a recent nightly build of [[Solr4.0]], start the example server and index the example data as shown in the [[http://lucene.apache.org/solr/tutorial.html|solr tutorial]]. With the Solr server running, you should be able to click on the example links and see real responses.
- click on the example links and see real responses.
In the example data, certain documents have a field called "store" (with a fieldType named "location" implemented via !LatLonType). Some of the points in the example data are:
+
{{{
<field name="store">45.17614,-93.87341</field> <!-- Buffalo store -->
<field name="store">40.7143,-74.006</field> <!-- NYC store -->
<field name="store">37.7752,-122.4232</field> <!-- San Francisco store -->
}}}
-
== geofilt - The distance filter ==
Now let's assume that we are at '''45.15,-93.85''' (which happens to be 3.437 km from the Buffalo store). We can use a '''geofilt''' filter to find all products (documents in our index) with the field '''store''' within '''5km''' of our position:
- [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!geofilt%20pt=45.15,-93.85%20sfield=store%20d=5}|...&q=*:*&fq={!geofilt pt=45.15,-93.85 sfield=store d=5}]]
+ . [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!geofilt%20pt=45.15,-93.85%20sfield=store%20d=5}|...&q=*:*&fq={!geofilt pt=45.15,-93.85 sfield=store d=5}]]
Sure enough, we find 8 products at the Buffalo store:
+
{{{
...
"response":{"numFound":8,"start":0,"docs":[
@@ -42, +43 @@
"store":"45.17614,-93.87341"},
...
}}}
-
== Spatial Query Parameters ==
The main spatial search related queries, '''geofilt''', '''bbox''', and '''geodist''' default to looking for normal request parameters, so any of '''pt''', '''sfield''', and '''dist''' may be factored out and only specified once in a request (even if multiple spatial queries are used).
Examples:
+
- * [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!geofilt%20sfield=store}&pt=45.15,-93.85&d=5|...&q=*:*&fq={!geofilt sfield=store}&pt=45.15,-93.85&d=5]]
+ * [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!geofilt%20sfield=store}&pt=45.15,-93.85&d=5|...&q=*:*&fq={!geofilt sfield=store}&pt=45.15,-93.85&d=5]]
- * [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!geofilt}&sfield=store&pt=45.15,-93.85&d=5|...&q=*:*&fq={!geofilt}&sfield=store&pt=45.15,-93.85&d=5]]
+ * [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!geofilt}&sfield=store&pt=45.15,-93.85&d=5|...&q=*:*&fq={!geofilt}&sfield=store&pt=45.15,-93.85&d=5]]
== bbox - Bounding-box filter ==
- Exact distance calculations can be somewhat expensive and it can often make sense to use a quick approximation instead.
- The '''bbox''' filter is guaranteed to encompass all of the points of interest, but it may also include other points that are slightly outside of the required distance. For our standard !LatLonType, this is implemented as a bounding box - a box made up of a range of lattitudes and longitudes that encompasses the circle of radius '''d''' (i.e. it will select the same or slightly more documents than '''geofilt''' will).
+ Exact distance calculations can be somewhat expensive and it can often make sense to use a quick approximation instead. The '''bbox''' filter is guaranteed to encompass all of the points of interest, but it may also include other points that are slightly outside of the required distance. For our standard !LatLonType, this is implemented as a bounding box - a box made up of a range of lattitudes and longitudes that encompasses the circle of radius '''d''' (i.e. it will select the same or slightly more documents than '''geofilt''' will).
The parameters are exactly the same as '''geofilt''', so the following request will still match everything in the Buffalo store:
+
- [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!bbox}&sfield=store&pt=45.15,-93.85&d=5|...&q=*:*&fq={!bbox}&sfield=store&pt=45.15,-93.85&d=5]]
+ . [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq={!bbox}&sfield=store&pt=45.15,-93.85&d=5|...&q=*:*&fq={!bbox}&sfield=store&pt=45.15,-93.85&d=5]]
Because the bounding box is less selective, if we change our distance to 3km it will still include the Buffalo store (which is actually 3.437 km away). If we used the more accurate '''geofilt''' at 3km, these documents not match. There are many scenarios when the bounding box can make sense though - especially if you are sorting by some other criteria anyway, or sorting by distance itself.
Since the !LatLonType field also supports field queries and range queries, so one can manually create their own bounding box rather than using bbox:
+
- [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq=store:[45,-94%20TO%2046,-93]|...&q=*:*&fq=store:[45,-94 TO 46,-93] ]]
+ . [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&fq=store:[45,-94%20TO%2046,-93]|...&q=*:*&fq=store:[45,-94 TO 46,-93]]]
== geodist - The distance function ==
-
'''geodist''' is a function query that yields the calculated distance. This gives the flexibility to do a number of interesting things, such as sorting by the distance (Solr can sort by any function query), or combining the distance with the relevancy score, such as boosting by the inverse of the distance.
Here's an example of sorting by distance ascending:
- [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&sfield=store&pt=45.15,-93.85&sort=geodist%28%29%20asc|...&q=*:*&sfield=store&pt=45.15,-93.85&sort=geodist() asc]]
+ . [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store&q=*:*&sfield=store&pt=45.15,-93.85&sort=geodist()%20asc|...&q=*:*&sfield=store&pt=45.15,-93.85&sort=geodist() asc]]
Or you could use the distance function as the main query (or part of it) to get the distance as the document score:
- [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store,score&q={!func}geodist%28%29&sfield=store&pt=45.15,-93.85&sort=score+asc|...&q={!func}geodist()&sfield=store&pt=45.15,-93.85&sort=score asc]]
+ . [[http://localhost:8983/solr/select?wt=json&indent=true&fl=name,store,score&q={!func}geodist()&sfield=store&pt=45.15,-93.85&sort=score+asc|...&q={!func}geodist()&sfield=store&pt=45.15,-93.85&sort=score asc]]
== Returning the distance ==
+ Returning distances (and any arbitrary function query value) is currently under development. As a temporary workaround, it's possible to obtain distances by using geodist or geofilt as the only scoring part of the main query.
- Returning distances (and any arbitrary function query value) is currently under development.
- As a temporary workaround, it's possible to obtain distances by using geodist or geofilt as the only scoring part of the main query.
-
+ = Advanced Spatial Options - Under Development =
+ SpatialSearchDev -- Covers things like Geohash, North/South Pole issues, other distance functions, etc.
- = Further Details - Under Development =
- SpatialSearchDev
-