[OSM-dev] MongoDB possibly unsuitable for OSM data

[Nolan Darilek]

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Hey, folks. I suppose that I might be wrong about this, and if so then
I'd love to be, but I thought that I'd share my recent findings here
either to inspire work in different directions if possible, or to close
a possibly useless avenue of work if not.

I have a real-time navigation app that stores its data in MongoDB, using
its geospatial queries. During the course of my work, I routinely found
that some queries were reliably slow while others were reliably fast.
We're talking differences of seconds, some taking 5, some 30, while
others were completed in under a second. Naturally, this is unsuitable
for an app that needs to provide near real-time feedback. I opened an
issue here, including my dump of an import of Texas' OSM nodes:

http://jira.mongodb.org/browse/SERVER-1392

It seems that I'm running up against limitations in MongoDB's
geohash-based mechanism. It's probably perfectly suitable for most
average geospatial-based searches, but not so much for the case of
rendering OSM data in reliably short bursts of time. The issue has been
marked wontfix.

I'm open to the possibility that I'm missing something, but have long
suspected that the geospatial support wasn't up to something of this
magnitude. I suppose that it might work as a data storage and
replication system, but if you need to get back data quickly then
MongoDB likely isn't a good fit.

Anyhow, I thought that I'd share, especially as some of us were
discussing use of MongoDB here a few weeks back.
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