[postgis-devel] Regular raster blocking (was: Real extent feature lost after metadata as views)

[Pierre Racine]

> Well this is false.. It is not because tiles are of the same size that they cover all
> the extent without leaving gaps or overlaps.
> 
> So we might want to replace the second condition (which becomes useless) by:
> 
> 2) There should be no overlaps or gaps in the global coverage.

The "all upper left corner on the same grid" become useless only if we do not allows gaps...

I'm fine with not allowing gaps but the original definition was allowing missing tiles. How is this different from "gaps"? I guess one is very difficult to differenciate from the other since we would check for gaps by computing the area of ST_Difference(global extent, ST_Union(all tiles)). If it is near to zero then we can say there is no gap.

This is why I think we should not allow any kind of gaps: gaps created by tiles of the same size aligned on a grid larger than the blocksizes and gaps created by missing tiles.

If some tiles become missing (because some application DELETEd it), then regular_blocking becomes false...

Pierre