You can already do this using BITSET -- I tracked 100 million objects with incremental integer keys during a migration process and it worked great. From what I

You can already do this using BITSET -- I tracked 100 million objects with incremental integer keys during a migration process and it worked great. From what I read, BITFIELD behaves differently -- it treats your data as a series of "packed" bits. So while with BITSET you operate on each bit individually, with BITFIELD you operate on a series of bits with a starting offset, and you have to be mindful of the length.