I run my own tile server with mod_tile. Every 4 month I would like to update the database and I would like that users, whe request tiles push the server to render new tiles.
Playing with generated tiles by setting the date with touch to different dates I found out that the tiles must be alter then around 7 month to be rendered again.
This is confusing because the settings in 000-default file persuade me that tiles would be rendered anyways with the default settings (I left the other settings untouched, because it seems to me that they are not relevant):
ModTileCacheDurationMax 604800 (7 days)
ModTileCacheDurationMinimum 10800 (3 hours + 3 hours for “fuzzy”= 6 hours)
ModTileCacheDurationMediumZoom 13 86400 (1 days)
ModTileCacheDurationLowZoom 9 518400 (6 days)
In that case I assume that tiles below zoomlevel 9 be rendered if they are older than 16,8 days (or a maximum age of 15,9 days below zoomlevel 13).
It didn’t worked as expected. I set the tiles using “touch -t” to one month older, then to 2 month … after 7 month the tiles were renewed. That’s much more than I expected by the explanation of the 000-default file.
In the 000-default file is something written about heuristics. Maybe they have something to do with that?
I hope that someone could explan me how to set the values to render e.g. tiles again at all zoomlevels which are older then half a year.