[OSM-dev] 'My first OSM experiences' - PDA Mapping software and the OSM mobile binary protocol

[Brett Henderson]

Karl Newman wrote:
> Heh, I was thinking along those lines, too, but I thought I'd wait 
> until your format stabilizes. It would be quite handy to have a 
> random-access data source for Osmosis without requiring a database 
> installation.
I'm not sure if you realise this but there already is one of those.  I 
can't reach the wiki at the moment but the tasks in question are:
--write-customdb
--read-customdb

I forget the details of the on-disk format but it's built around the 
osmosis store classes so uses osmosis specific object serialisation.

The --read-customdb task doesn't actually stream data to downstream 
tasks, it provides the data in the form of a "dataset" object.  This can 
be consumed by tasks such as --dataset-dump which will stream from the 
dataset, but it can also be consumed by any task wishing to access data 
randomly.

Performance isn't great for large datasets which is why I created the 
pgsql-simple schema.  I've never been able to get an on-disk format to 
scale nearly as well as a real database.

I also wrote a set of tasks based on one the Berkeley DB Java Edition 
but deleted it because performance was even worse.

Brett