[MapProxy] MBTiles: multiple grids stored in single tiles table

[Just van den Broecke]

Hi,

I am trying to use two grids (GLOBAL_MERCATOR and the Dutch National 
tiling grid) with MBTiles caching. Something like:

   my_mbtiles_cache:
     grids: [dutch_grid, merc_grid]
     sources: [my_wms]
     format: image/jpeg
     cache:
       type: mbtiles
       [filename: my.mbtiles]

With e.g. Filecaches, one cache per grid is created. But with MBTiles 
the tiles for the two grids are created in a single "tiles" table in a 
single sqlite file "my.mbtiles". I would expect two MBTiles files, named 
after the grids. Also if I leave "filename" out a single 
"my_mbtiles_cache.mbtiles" file is created. (Defining two MBTiles caches 
is a bit complicated now, as this would require renaming Layers).

I realize MBTiles assumes a single tiling schema/grid, 
GLOBAL_(WEB)MERCATOR . Possibly I should move to sqlite or geopackage 
caches, the latter storing more metadata and a single tiles table per 
grid...

Best,

Just van den Broecke