[OSM-dev] all things to all people

Brett Henderson brett at bretth.com
Thu Apr 24 04:59:29 BST 2008

On Wed, Apr 23, 2008 at 7:54 AM, Frederik Ramm <frederik at remote.org> wrote:

> Hi,
> >    Since the minute-diff was introduced OSMXAPI has been running, on
> >    average, about 6 minutes behind the main database.
> Sigh, this project is too large already for one person to keep the
> overview. Minute diffs you say. Hadn't heard of them until now, thanks
> ;-)

I really should do some more advertising, this has come up a few times now

I've also created tasks for populating a PostGIS "simple" schema which is
useful for maintaining a local replica of OSM data.  Latest SVN osmosis has
tasks for merging changesets into it so you could in theory have a PostGIS
database kept within 6 minutes of the main API.  It should be very efficient
at serving bounding boxes although only real-world testing will confirm
this.  There's still a few TODOs in terms of keeping a database in sync that
only stores a subset of the planet, at the moment I can only apply whole
planet diffs.

> >    IMHO this is good enough for all purposes, except editing, which
> >    obviously needs to act on the live data.
> Have you had a chance to compare the result from a week's worth of
> minute diffs with the planet? Is it considered safe to work on the
> diffs alone, or still recommended to re-synchronize with the planet
> once a week?

I'm not aware of any issues but will be interested if people detect
problems.  The reason osmxapi lags by 6 minutes is because I have osmosis
set to only read data that is at least 5 minutes old.  This could be dropped
further but there's a risk of long running inserts having an old timestamp
and getting missed.  Shouldn't happen most of the time but if a long running
query locks a table it is possible.

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