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If you are working with location data, Mongo has built in geospatial indexing built in since 1.4 (earlier in the unstable builds) - http://www.mongodb.org/displ

If you are working with location data, Mongo has built in geospatial indexing built in since 1.4 (earlier in the unstable builds) - http://www.mongodb.org/display/DOCS/Geospatial+Indexing http://www.mongodb.org/display/DOCS/Geospatial+Indexing which has been a big draw for a number of people I know using it (it looks like 1.8 brings spherical distances to the stable branch which makes the geo lookups a lot more useful if you need accurate distances and not just near by lookups).

igrekel 16y ago
Interesting I was planning to toy with location data, do you know how it compares with Postgresql extension PostGIS?
- crux_ 16y ago
  If by "location data" you have points, and the only location operations you need are distance or bounding-box searches, it may do the trick. If you're interested in polygons, lines, etc; more physically accurate (and completely implemented) distance queries, spatial joins, aggregation, 3D and surveyor-annotated data, set-theoretic operations ... PostGIS is far and away the way to go. It's far more mature and debugged than any of the NoSQL geospatial stuff I've seen, not only WRT correctness but also performance. As a point of reference: There's a growing legion of geographers who do all their vector work in SQL using PostGIS. All that said, for some applications, being tied to the relational model is a deal breaker. Just know that in terms of capability and maturity on the geospatial front, you'll be trading off a Cadillac for a partially assembled rocket sled.
crux_ 16y ago
I got excited and looked it up. > We don't currently handle wrapping at the poles or at the transition from -180° to +180° longitude, however we detect when a search would wrap and raise an error. generalized grumble Why does everyone always seem to punt on doing geospatial right? It's not _that_ hard.
- gt384u 16y ago
  Why not go ahead and help them? I'm sure they'd be happy to have the assistance. Fork mongo from github at https://github.com/mongodb/mongo https://github.com/mongodb/mongo . Happy hacking!
  - crux_ 16y ago
    You know, nobody ever replies to these comments with an "I will", but I'm seriously considering it. (It's a nice opportunity to publicly show off a specialty/core competency and brush up a bit on C++ a the same time. I'm not that easily provoked into action by internet commentary! ;) ) But, looking at the source, I think I will be probably a Bad Contributor and end up with a gigantic pull request and a (mostly) full re-implementation...
- thibaut_barrere 16y ago
  > Why does everyone always seem to punt on doing geospatial right? It's not _that_ hard. Do you mean you think they don't know how to do it? As I followed the roadmap on this specific point, it looks more like an incremental development to me: they first used rectangular coordinates in 1.6, then a spherical model in 1.7 etc. It allows to bring a more lightweight solution quickly to people that need it (like me), then to evolve based on the feedback etc.
  - crux_ 16y ago
    The problem I have is at least partly one of truth in advertising. For example: If they were truly using a "spherical model", then one would not expect to have queries fail at the poles & dateline, would you? At least it is documented and fails hard with an error rather than giving wrong results, so a developer can quickly figure out the weak spots --- though I bet a lot of people would prefer the wrong results to queries that cause exceptions in their systems. > Do you mean you think they don't know how to do it? I think it has more to do with the absurdly low bar they've set for themselves to check the "geospatial" box than it does with competence.
    - 16y ago
look_lookatme 16y ago
In reference to the OP, when comparing Mongo and Postgres, I wouldn't bring up geo...

igrekel 16y ago

Interesting I was planning to toy with location data, do you know how it compares with Postgresql extension PostGIS?

crux_ 16y ago
If by "location data" you have points, and the only location operations you need are distance or bounding-box searches, it may do the trick. If you're interested in polygons, lines, etc; more physically accurate (and completely implemented) distance queries, spatial joins, aggregation, 3D and surveyor-annotated data, set-theoretic operations ... PostGIS is far and away the way to go. It's far more mature and debugged than any of the NoSQL geospatial stuff I've seen, not only WRT correctness but also performance. As a point of reference: There's a growing legion of geographers who do all their vector work in SQL using PostGIS. All that said, for some applications, being tied to the relational model is a deal breaker. Just know that in terms of capability and maturity on the geospatial front, you'll be trading off a Cadillac for a partially assembled rocket sled.

crux_ 16y ago

I got excited and looked it up. > We don't currently handle wrapping at the poles or at the transition from -180° to +180° longitude, however we detect when a search would wrap and raise an error. generalized grumble Why does everyone always seem to punt on doing geospatial right? It's not _that_ hard.

gt384u 16y ago
Why not go ahead and help them? I'm sure they'd be happy to have the assistance. Fork mongo from github at https://github.com/mongodb/mongo https://github.com/mongodb/mongo . Happy hacking!
- crux_ 16y ago
  You know, nobody ever replies to these comments with an "I will", but I'm seriously considering it. (It's a nice opportunity to publicly show off a specialty/core competency and brush up a bit on C++ a the same time. I'm not that easily provoked into action by internet commentary! ;) ) But, looking at the source, I think I will be probably a Bad Contributor and end up with a gigantic pull request and a (mostly) full re-implementation...
thibaut_barrere 16y ago
> Why does everyone always seem to punt on doing geospatial right? It's not _that_ hard. Do you mean you think they don't know how to do it? As I followed the roadmap on this specific point, it looks more like an incremental development to me: they first used rectangular coordinates in 1.6, then a spherical model in 1.7 etc. It allows to bring a more lightweight solution quickly to people that need it (like me), then to evolve based on the feedback etc.
- crux_ 16y ago
  The problem I have is at least partly one of truth in advertising. For example: If they were truly using a "spherical model", then one would not expect to have queries fail at the poles & dateline, would you? At least it is documented and fails hard with an error rather than giving wrong results, so a developer can quickly figure out the weak spots --- though I bet a lot of people would prefer the wrong results to queries that cause exceptions in their systems. > Do you mean you think they don't know how to do it? I think it has more to do with the absurdly low bar they've set for themselves to check the "geospatial" box than it does with competence.
  - 16y ago

look_lookatme 16y ago

In reference to the OP, when comparing Mongo and Postgres, I wouldn't bring up geo...