80n wrote: > > Replication of changesets is on my undocumented long term TODO > list for > osmosis (I should add it to trac) but I don't know when I'll be > able to > do it. I had some discussions with Shaun and Matt a while back on how > this might be done efficiently. Identifying changesets for > replication > is a bit tricky and would probably involve two passes, first pass > would > identify all changesets created in a time interval, and the second > pass > would identify all changesets modified (ie. have entities referring to > them) in a time interval. Once identified they could be read and > included in a changeset file just like any other entity. > > > Perhaps you only need to worry about exporting the changeset headers. > The members of a changeset can be derived from the elements themselves. Yes, that is fine, in fact I think that's what we were planning to do ... my memory is hazy :-) The header info is the difficult bit because it changes over time. From memory (I don't have the schema handy) the main issue is the bounding box fields. These can be updated over time as new entity updates are added to the changeset. I agree that only the header info needs to be extracted, but it needs to be included in every changeset that has an entity referring to it in case the bounding box was updated since the last replication.
Is the bounding box info updated within the same transaction as entity updates or can it be updated asynchronously with a separate daemon? I remember discussions about bbox updates only occurring occasionally (ie. the bbox is made slightly larger than necessary to avoid large numbers of writes) but I'm fairly sure they're updated synchronous at the same time as the entity causing the update, at least I hope so. Brett _______________________________________________ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
