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From "Christopher O'Connell" <>
Subject ExternalJ Framework and Geospatial index
Date Mon, 09 Nov 2009 06:34:10 GMT
Unfortunately, CouchDB does not include geo-spatial indicies, and geoCouch
requires a ton of dependancies, and is complicates. ExternalJ is a framework
(sort of) to make writing external processes for CouchDB simpler. ExternalJ
also comes with several useful applications, including a “geo” application
which implements a geo-spatial index on a database. It's only dependency is
java 1.5 (ExternalJ will compile against 1.4, but ExternalJ-Geo needs some
of the concurrency structures in 1.5). It's fast a lightweight. At the
moment, it keeps indicies in memory, but I'll be adding file storage soon. To read about it and installation
instructions To get it to read more about it

Better documentation in the coming days.

To give some very general performance numbers, with CouchDB 0.10.x current
and ExternalJ 0.10.x.7, I was able to index the entire contents of the FAA's
us airport database (about 20,000 entries). The index took about 60 seconds
to build and lived in about 800 KBytes of memory (total ExternalJ overhead
about 4 MB). Querying the nearest 10 entries to an arbitrary point takes
about 40ms the first time and almost 0 after that (query cache). Finding all
the points within x miles of an arbitrary point (using a formula "accurate"
on the surface of the earth) takes 30-300ms, and will be further optimized
with distance calculation caching in the future.

It runs fine along with Couch on a 256 MB "slice" (a Xen
instance). Also running, nginx proxy and php_cgi.

In addition to the Geo applicaiton, I've included a trivial HelloWorld
application and a somewhat trivial Say application which can be used as the
starting point for your own external process. ExternalJ can also be run from
the console, so that you can "see" the interaction with couch, and there are
special "$command" commands outlined on the web page to give you some
insight into running times and heap size.

If you have any questions, please drop me an e-mail or drop a comment on the
ExternalJ page.

~ Christopher

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