On Sonntag 19 April 2009, Maarten Deen wrote: > Ok, you're checking tiles as you go. My idea was to select the lowest > renderdate and rerender that tile. That is less dirty but requires a > database with the renderdates, or 16 million http requests to get all dates > (which would make it an awful hack).
Well, I do not have direct database access and there is no lighweight API for requesting the data so I do have to request the status via http. But my idea is to do this a bit more intelligent and store already made quiries and requests in a local database with some additional info (quiry_date, tile_date, request_date, tile_changed_date) where the tile_changed_date comes from the OSM API. In case I trust the mechanism that tiles are automatically rerendered when the data in the tile has changed I will not have to check the status again until even this date is too old. I was also thinking of storing the status of all tiles into the local database. This would initially require a complete quiry of all 16 million tiles. But afterwards it would only quiry empty tiles, if they are next to a tile with content. This would give me the possibility to leave empty sea and land tiles alone unless a neighbour tile gets content. > > Requests are being sent with priority 4 and source > > 'tile-reliability-checker'. Max age is currently set to one month since > > the tiles seem to have been restored from a backup of 2009-03-04. At > > least I cannot see tile dates older that date and younger than > > 2009-04-14. > > There are. See tile (12, 2100, 1359) from 2009-01-14. There are more tiles > in the Netherlands from januari. Sorry, my logic was wrong. I meant younger than 2009-03-04 and older than 2009-04-14. I haven't seen any tile date inbetween these dates. Oldest tile seen recently was 2008-09-18. > > This situation results in rather high rate of render requests. I think in > > the future the situation will get better. > > > > The script takes approx. 0.4 seconds for each tile. Means, that for a > > complete world check with 16 mio tiles it would take approx. 77 days to > > finish. Isn't this a good result if the max age for a tile is set to two > > months??? > > Yup. Sounds as a reasonable hack for not having a direct access to all > tile's renderdates. Yup. I'm currently implementing a check for the queue length. The queue length would be checked after each thousand requests and would go into a sleep loop (15 minutes sleep) if queue has more than 10,000 entries und would go out of sleep loop if queue length has fallen below 5,000 entries. Regards, Andre _______________________________________________ Tilesathome mailing list [email protected] http://lists.openstreetmap.org/listinfo/tilesathome
