Jens has hinted at a project over at Mojang calling it “Anvil” and it’s a new format for minecraft maps.
Some of the major changes are:
- Maximum build height has been increased to 256 (was 128)
- Empty sections of the world are not loaded into memory
- Block ids have been increased to 4096 (was 256) by adding a 4 bit data layer (similar to how meta data is stored)
- Block ordering have been changed from x/z/y to y/z/x in order to improve compression
- Packets for sending chunks have been updated (a full 128-high chunk is smaller than the old format, and a chunk with lots of empty space is much smaller)
- Biomes are saved per x/z column, which means they can be altered by tools
The next snapshot, and Minecraft 1.2, will automatically convert worlds to the new format. The files of the current format (“McRegion”) will remain in your save folder, if you need to restore them for some reason. Check out the full Mojang blog post here.