On Wed, 2009-10-21 at 13:07 +0200, Frederik Ramm wrote: > Hi, > > this is mostly a question to Jon Burgess I guess but I'm asking on > dev because I figure that others might also be interested. On the main > OSM tile server, do you apply the diffs while you render tiles at the > same time, and have you performed any PostGIS magic to ensure that tile > rendering still has priority while diffs are being applied? > > On my setup, I have resorted to using two separate databases (on > separate machines) in order to be able to update one while the other > renders tiles; doing both at the same time just slowed down tile > rendering to a crawl. Now this was not fancy hardware but a reasonably > modern quadcore processor and SATA disks - do fat RAM & fast disks make > the difference between possible and impossible?
I use a single DB on the tile server but perform the full import into a new set of tables. The replication diffs are applied into the main tables roughly once per minute in parallel with any rendering. Performing concurrent rendering & importing definitely does slow things down. I have seen some evidence that running both slows things down to less than half the speed of running each individually but I have not tried to quantify it. During the full planet import I will import the data into a new set of tables with the renderer accessing the old data. A breakdown of the steps I do when performing the bulk update is: - Download new planet dump - Stop the diff import - Drop the tables used by the diffs: nodes, ways, rels. - Import the new data with a new table prefix (osm2pgsql -p ...) - Wait many hours for import to complete - Stop rendering - Drop old point, line, polygon & roads. - Rename new tables with the planet_osm_ prefix - Restart rendering daemon - Restart diff import but with tile invalidation disabled - Wait for diffs to catch up (may take a day or two) - Turn on tile invalidation - Touch the planet_import_complete flag to force all tiles to re-render During those steps I also run the coastcheck program to generate an updated set of coastline shapefiles. Jon _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
