[OSM-dev] Timestamp in PBF files

[Frederik Ramm]

Hi,

On 11/21/2012 11:50 AM, marqqs at gmx.eu wrote:
>> It should have a planet URI (or a planet URI and a list of mirrors) of
>> what planet it corresponds to. That way a user merely needs to say
>> 'update planet' and everything else can be automated.
>
> Please don't. These data aren't necessary. Same applies to sequence numbers.
>
> Since a year or so planet files can be updated by a single "update" command. This command first determines the age of the old file, then it downloads all needed planet change files,

... by making hard-coded assumptions about where to get them from, and 
that's precisely what Scott meant. After all, there might be other 
projects using the OSM toolchain (e.g. fosm.org) and they publish their 
own diffs and might publish their own PBF files, and if you use their 
PBF file and try to update that from some openstreetmap.org URL that 
won't work.

So if you really want to be able update the file without relying on some 
out-of-band knowledge ("I downloaded this file from Geofabrik and I 
happen to know that they use openstreetmap.org as their data source"), 
then you would need the URI in the file.

The same if someone were to operate an OSM mirror and publish their own 
diffs, and you might choose to synchronize with them rather than with 
openstreetmap.org - even here, what the mirror publishes in a diff with 
the time stamp X is not necessarily identical with what OSM publishes in 
a diff with the same time stamp, and knowledge about where to update the 
file from would be essential.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"