# A couple of geo-related questions **URL:** \ **Category:** Elasticsearch\ **Created:** [October 7, 2010, 10:24pm UTC](https://discuss.elastic.co/t/a-couple-of-geo-related-questions/3423 "2010-10-07T22:24:12Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Andrei](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/andrei/32/2856_2.png) [@Andrei](https://discuss.elastic.co/u/Andrei)\ **Post date:** [October 7, 2010, 10:24pm UTC](https://discuss.elastic.co/t/a-couple-of-geo-related-questions/3423/1 "2010-10-07T22:24:12Z")
How is the geo-indexing implemented: is it a btree- or quadtree-based index, a geohash one, or something else? Curious how it compares to Mongo's geo support. Also, would it be possible to have a facet for returning the centroid and the minimum bounding box for the set of results found via the geo filters? -Andrei ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [October 8, 2010, 11:17am UTC](https://discuss.elastic.co/t/a-couple-of-geo-related-questions/3423/2 "2010-10-08T11:17:19Z")
On Fri, Oct 8, 2010 at 12:24 AM, Andrei [andrei@zmievski.org](mailto:andrei@zmievski.org) wrote: > How is the geo-indexing implemented: is it a btree- or quadtree-based > index, a geohash one, or something else? Curious how it compares to > Mongo's geo support. I am not sure how mongodb implemented geo support, in elasticsearch, because of its search engine / inverted index nature, it is implemented quite differently. When searching, you basically traverse a set of document ids (internal ondes, not the \_id) that correspond to the relevant query. What you want is to check (filter) or collect (facets) as fast as possible data based on that doc id. The way you usually do it is by loading the relevant data to memory and creating a docId -\> value (which is the inversion of the inverted index). > Also, would it be possible to have a facet for returning the centroid > and the minimum bounding box for the set of results found via the geo > filters? Should be possible, need to look / learn more into how to do it. > -Andrei As a side note, I have discovered that having multiple locations per doc does not work correctly. Checking how to fix that, might require a different structure to be stored in the index. ---
**Author:** ![Andrei](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/andrei/32/2856_2.png) [@Andrei](https://discuss.elastic.co/u/Andrei)\ **Post date:** [October 8, 2010, 6:07pm UTC](https://discuss.elastic.co/t/a-couple-of-geo-related-questions/3423/3 "2010-10-08T18:07:17Z")
So how does this work with a match\_all query? Does it mean that it needs to scan all the documents and check that the value of geo- coordinate is in the bounding box? The bounding box is actually the [Minimum bounding rectangle - Wikipedia](http://en.wikipedia.org/wiki/Minimum_bounding_rectangle). Worth checking on R-trees linked from there too. -Andrei On Oct 8, 4:17 am, Shay Banon [shay.ba...@elasticsearch.com](mailto:shay.ba...@elasticsearch.com) wrote: > I am not sure how mongodb implemented geo support, in elasticsearch, because > of its search engine / inverted index nature, it is implemented quite > differently. When searching, you basically traverse a set of document ids > (internal ondes, not the \_id) that correspond to the relevant query. What > you want is to check (filter) or collect (facets) as fast as possible data > based on that doc id. The way you usually do it is by loading the relevant > data to memory and creating a docId -\> value (which is the inversion of the > inverted index). > > Also, would it be possible to have a facet for returning the centroid > > and the minimum bounding box for the set of results found via the geo > > filters? > > Should be possible, need to look / learn more into how to do it. > > > -Andrei > > As a side note, I have discovered that having multiple locations per doc > does not work correctly. Checking how to fix that, might require a different > structure to be stored in the index. ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [October 8, 2010, 6:56pm UTC](https://discuss.elastic.co/t/a-couple-of-geo-related-questions/3423/4 "2010-10-08T18:56:39Z")
On Fri, Oct 8, 2010 at 8:07 PM, Andrei [andrei@zmievski.org](mailto:andrei@zmievski.org) wrote: > So how does this work with a match\_all query? Does it mean that it > needs to scan all the documents and check that the value of geo- > coordinate is in the bounding box? Yes, though match\_all is not really the common case. It makes little sense to build another indexing data structure just for this case, while on all other case, the best solution is the one I outlined. But, even with match\_all, the execution is all in memory, so the difference would be negligible if not faster.... . Sharding helps scaling out as well. > The bounding box is actually the > [Minimum bounding rectangle - Wikipedia](http://en.wikipedia.org/wiki/Minimum_bounding_rectangle). ok. > Worth checking on R-trees linked from there too. Irrelevant. R-trees are nice, but make little sense when coupled with how a search engine works and providing geo on top of it. > -Andrei > > On Oct 8, 4:17 am, Shay Banon [shay.ba...@elasticsearch.com](mailto:shay.ba...@elasticsearch.com) wrote: > > > I am not sure how mongodb implemented geo support, in elasticsearch, > > because > > of its search engine / inverted index nature, it is implemented quite > > differently. When searching, you basically traverse a set of document ids > > (internal ondes, not the \_id) that correspond to the relevant query. What > > you want is to check (filter) or collect (facets) as fast as possible > > data > > based on that doc id. The way you usually do it is by loading the > > relevant > > data to memory and creating a docId -\> value (which is the inversion of > > the > > inverted index). > > > > Also, would it be possible to have a facet for returning the centroid > > > and the minimum bounding box for the set of results found via the geo > > > filters? > > > > Should be possible, need to look / learn more into how to do it. > > > > > -Andrei > > > > As a side note, I have discovered that having multiple locations per doc > > does not work correctly. Checking how to fix that, might require a > > different > > structure to be stored in the index. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 4:18am UTC](https://discuss.elastic.co/t/a-couple-of-geo-related-questions/3423/5 "2017-07-06T04:18:12Z")