2008/5/27 Karl Newman <[EMAIL PROTECTED]>: > On Mon, May 26, 2008 at 8:33 AM, Tom Hughes <[EMAIL PROTECTED]> wrote: >> >> In message <[EMAIL PROTECTED]> >> Ludwig <[EMAIL PROTECTED]> wrote: >> <snip> >> Map data for editing purposes will always have to come from the >> master database anyway, or you might get an old version which you >> are then unable to upload. >> > That may hold true for "live" editors such as potlatch, but for offline > editors like JOSM, if you download from the master database server, do some > editing and then upload, the editing time is going to far exceed any > replication delay, so you could instead download from a replication server, > do your edits and then upload to the master server. The chance of a > collision/version mismatch is increased only a miniscule amount. >
Yes... and no. The problem here is the remedial action taken by the user/editor: they're going to try to work out the conflicts by downloading the latest version of the region. If this comes off a replication server that's a couple of minutes behind, then they're going to be sitting there retrying for a couple of minutes before they can actually get a version they can upload. It may be possible to fix many of these cases by redesigning the fail returns of the API uploads... but if not thought through then this could end up pretty tedious for the editor. There's also then the problem of inconsistent downloads: if I download a map area twice I expect the second time to be identical or a later version. If I'm pulling it from a couple of different replication servers, one 1 minute behind, one 2 minutes behind because of an earlier high load, then the second map call could actually return an older version. This may not be much of an issue, but it's another thing editors would have to watch out for. Dave _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
