[OSM-dev] osm2pgsql-64 and benchmarks

[Frederik Ramm]

Martijn,

On 06/22/11 08:31, Martijn van Oosterhout wrote:
> The reason I went for arrays of integers is diskspace (4 bytes per
> node rather than 40 for a whole row). Did you compare that?

When I initially made osm2pgsql-64 I looked at the database size on disk 
and found it to be about 20% bigger in total when using 64-bit IDs than 
when using 32-bit IDs. Sadly I forgot to record the disk usage in the 
experiment from this thread.

Another thing to consider is of course memory usage; osm2pgsql will 
require more RAM (or achieve less caching performance with the same 
amount of RAM) when you do 64-bit IDs. I felt that the node caching 
could probably be cleverly modified so that it would only require more 
memory for those IDs that really were outside the 32bit range but 
haven't ventured into that.

Bye
Frederik