[OSM-dev] Planet dump updates to include relations as an extra file

Andy Allan gravitystorm at gmail.com
Wed Apr 9 08:41:47 BST 2008


Given that #relations < #ways < #nodes, and you (generally) need to
know about all the relations before you process the ways, and you need
to know which ways you are interested in before deciding which nodes
to keep - would it not make sense to dump the relations into the file
first, followed by the ways, then the nodes last?

Albeit I'm only thinking of osm2pgsql, maybe there's other things that
wouldn't work this way round.


On Tue, Apr 8, 2008 at 11:06 PM, Jon Burgess <jburgess777 at googlemail.com> wrote:
> I added a couple of command line switches to the planet dump tool:
>  $ planetdump --help
>  Usage error:
>         planetdump [--nodes] [--ways] [--relations]
>  Writes OSM planet dump to STDOUT. If no flags are specified then all
>  data is output. If one or more flags are set then only the requested
>  data is dumped.
>  The script which runs the weekly dump has been changed to produce a new
>  file with just the relations. Tomorrow we should see:
>   relations-080409.osm.bz2
>  The contents on the main planet.osm dump is unchanged. It still contains
>  the relations too, this is an additional copy of the data.
>  It is much more efficient to parse the planet file if you know up front
>  which nodes and ways are referenced by relations. This will make the
>  relation handling on osm2pgsql much more efficient (and will probably
>  help other tools too).
>         Jon
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