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Re: [Maposmatic-dev] Re: [OSM-dev] [ANNOUCEMENT] MapOSMatic: automatic g

From: David Decotigny
Subject: Re: [Maposmatic-dev] Re: [OSM-dev] [ANNOUCEMENT] MapOSMatic: automatic generation of cities' map from OpenStreetMap data
Date: Thu, 24 Sep 2009 09:43:09 +0200
User-agent: Thunderbird (X11/20090817)


Richard Weait wrote:
> I hope that you do not follow Frederik's perfectly reasonable
> suggestion.  I'd selfishly like to see North American cities available
> on OSMatic some day.

Sorry to disappoint you, but for now the perspectives are not too
exciting on that front. We cannot manage to update the planet (by way of
a daily diff) in less than ~540mn (~9h) on our server. I tried to tweak
the sql server a bit, but... couldn't decrease the update time by more
than 20mn. Worst of all: the db is unusable while being updated. That
would come down to around 10h downtime a day (~38% downtime according to
the current figures we have). For more info:

I didn't try hourly diffs, but if things behave linearly, the updates
would take ~23mn every hour: almost 1/2h downtime every hour ! Anyway,
we probably have to try this anyway. But for that, we need to catch up
with the latest planet (in progress: we are lagging 8 days behind, for now).

If none of this proves reasonable, then I'm afraid we'd have to limit
ourselves to europe... if it's reasonable. Otherwise, maybe one
alternative would be to load-balance on 2 servers: one serving the maps
while the other updates its planet, and vice-versa (we don't have enough
disk space to do both on our server). Any server available out there ?

Another, more satisfying, solution: find the right way to make the
update time shrink by a factor of 5 to 10. For now, we are running the
updates with: osm2pgsql -s -C 1500 -a "the_daily_diff.osc.gz" with
osm2pgsql 0.67-17616. We'd loooove not to use the '-s' (slim mode)
option but apparently it's not possible for updates. The server is
running Jaunty x86_64 on a Intel(R) Pentium(R) Dual  CPU  E2180  @
2.00GHz CPU (2GB RAM).

Any hint more than welcome !


PS: I am not a subscriber of osm-dev; thanks to Cc me.

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