On Mon, Jan 10, 2011 at 1:31 PM, Andy Allan <[email protected]> wrote: > On Mon, Jan 10, 2011 at 12:44 PM, Robert Scott <[email protected]> wrote: >> On Monday 10 January 2011, Kai Krueger wrote: >>> Depending on how far you really want to scale, I think a lot of the >>> necessary components are already in place. If none of the "out of the box" >>> solutions such as the new Postgresql 9.0 replication mechanism work, we >>> would possibly get a fair distance by splitting out reads and writes onto >>> separate db servers. >> >> This is how the postgres 9 replication works. The replicating servers become >> "hot standbys" which you can use for read requests. So in theory the read >> requests could be scaled quite easily once set up. Atomicity of the API >> would potentially suffer though. > > We need to be careful about what purposes we scale read requests. A > lot of the read-load on the API is using the data for non-editing > purposes (such as rendering or other 'cool' things that need /map > calls) and this should be avoided[1]. The advantage of making sure > that read-scaling for non-editing purposes is *not* via db-replication > is that anyone (and everyone) can add their own servers to scale > things out. For example, everything that currently fetches live data > via the diffs at planet.openstreetmap.org (or a service that depends > on them, like xapi, geofabrik extracts etc) is a Good Thing, and > everything that currently fetches live read-only data via > osm.org/api/0.6/map is a Bad Thing. > > It's a bad thing since there's only so much hardware the OSMF can > own/host/run, but there's nothing stopping 50 other organisations > running cool stuff based off of planet.openstreetmap.org
it seems postgres 9 isn't able to do temporary table creation on hot-standby servers [1]. maybe this is something that'll be fixed in future versions (but it doesn't seem to be on the TODO [2]) or maybe it's an opportunity to put a bounty to good use. cheers, matt [1] http://www.postgresql.org/docs/9.0/interactive/hot-standby.html#HOT-STANDBY-USERS [2] http://wiki.postgresql.org/wiki/Todo _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
