Hello everyone, I'm working on a application that uses Cassandra and has a geolocation component. I was wondering beside the slides and video at http://www.readwriteweb.com/cloud/2011/02/video-simplegeo-cassandra.php that simplegeo published regarding their strategy if anyone has implemented geohash storage and search in cassandra. The basic usage is to allow a user to find things close to a geo location based on distance radius.
I though about a couple of approaches. 1. Have the geohashes be the keys using the Ordered partitioner and get a group of rows between keys then store the items as columns in what it would end up looking like wide rows since each column would point to another row in a different column family representing the item nearby. 2. Simply store the geohash prefixes as columns and use secondary indexes to do queries such as >= and <=. The problem I'm facing in both cases is ordering by distance and searching neighbors. The neighbors problem is clearly explained here: https://github.com/davetroy/geohash-js Once the neighbors are calculated an item can be fetched with SQL similar to this. SELECT * FROM table WHERE LEFT(geohash,6) IN ('dqcjqc', 'dqcjqf','dqcjqb','dqcjr1','dqcjq9','dqcjqd','dqcjr4','dqcjr0','dqcjq8') Since Cassandra does not currently support OR or a IN statement with elements that are not keys I'm not sure what the best way to implement geohashes may be. Thanks in advance for any tips.
