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

[Brett Henderson]

Karl Newman wrote:
> On Wed, Jan 7, 2009 at 2:28 PM, Brett Henderson <brett at bretth.com 
> <mailto:brett at bretth.com>> wrote:
>
>     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
>
>
> Actually yes, I was aware of that one, but I recall that you said the 
> performance was not good and I thought you had removed that one for 
> performance reasons (I didn't pay close attention; I guess it was the 
> BDB that you removed instead).
I forget now :-)  I might have been going to remove it and changed my 
mind.  If new features come along that are difficult to support I'll 
drop it.  I don't think anybody uses it.