[Tilesathome] another idea for more performance

[OJW]

On Sunday 27 May 2007 22:51, Damian Sulewski wrote:
> 2. if server receives a blank_tile it removes all meta info and files
> under it from disk, marking only this tile as blank.

What if that area contains features which are only visible on a higher zoom 
level?  You don't know that the subtiles are blank just because the tile 
above is.

Also, this makes it trivial to delete the whole world, by uploading a blank 
tile at zoom 0.