On Mon, Jan 18, 2010 at 9:23 PM, Steve Hill <st...@nexusuk.org> wrote:
> On Mon, 18 Jan 2010, Frederik Ramm wrote: > > > Yes, and I have explained about 1.000 times that what comes out of > Osmosis > > You may have explained all this on this list 1,000 times (which I very > much doubt), but I couldn't find any of it properly documented anywhere on > the Wiki... > If it helps, all Osmosis tasks are documented here: http://wiki.openstreetmap.org/wiki/Osmosis/DetailedUsage The documentation may not be comprehensive and does assume some knowledge around how Osmosis pipelines are constructed, but it is accurate and up to date to the best of my knowledge. > > > WILL be one single (daily or 1.73daily or 2.918daily or 0.002daily > depending > > on how often you call it) file. > > I'd wager that having Osmosis download 1440 minutely diffs and assemble > them into a daily diff is going to take significantly more time than just > wgetting a single daily diff. However, I can't verify my assumption at > the moment because I'm having to spend my time battling (and currently > failing) to get a honking great Java application (Osmosis) to work to do > all this. I'm afraid this seems like a retrograde step to me, compared > with the relative simplicity of stuffing diffs directly into osm2pgsql. > Yes, of course it will take longer to download a large number of diffs files than to download one. However I suspect the main overhead will be actually importing the files into PostgreSQL itself. Note that there are in fact hourly files that can be used but like all new replication files they aren't exactly time aligned which makes it harder to switch between them. http://planet.openstreetmap.org/hour-replicate/ "Honking great Java application" is a little excessive, we're hardly talking about installing a JEE server here. Does this refer to the download size, the fact that it runs on Java, or that fact that it seems hard to install. The binary distribution is approximately 8MB, it consumes a very reasonable amount of RAM regardless of dataset size (very approximately 50MB), and I've gone to a lot of effort to make installation as simple as possible. Assuming you have a working Java 1.6 runtime (which should be available out of the box on any modern Linux distribution, and available as a simple installer for Windows), then installing Osmosis is as simple as downloading the latest zip file, and extracting it. Yes, there is some setup required to establish replication, but again I've attempted to keep all locally maintained state simple and all exposed in text files. I agree that it would be nice from a user perspective to have a single application (ie. osm2pgsql) just do everything automatically but that has downsides. In particular it requires implementing the replication mechanism in every tool that wishes to support it. The Osmosis --rri has been written to be re-usable by any tool that can consume an *.osc file. It is well debugged and shown itself to be reliable. Replication is not as simple as it might seem, there are a lot of edge cases once you start taking long running transactions, unreliable network connections, zero server-side state, and a large consumer base into account. I guess a way to resolve this would be to create a shell script that wraps all of this together, but I guess nobody has bothered up to this point. Brett
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