view tests/0015/short-description @ 108:bc141fd1dc41

New on-disk format!

* new magic number: "o2db" rather than "O2DB".  Check for the old one
  and give a helpful error message.  (We could in principle handle the
  old databases transparently, but since only MC has actually used them
  and he has indicated that this is not desperately necessary...)

* add fields to header: a file format version (currently 0; we have
  2^32-1 revisions to make before we have to worry...) and fields for
  the offsets of the various tables.  This is hopefully a little bit
  more futureproof: we can move the default locations of the tables
  around, and even adding new optional tables can be done easily in a
  fairly transparent manner (if the relevant header field is 0, don't
  use that feature).

* align regions to the appropriate 32-word boundary.  This gives us some
  space to breathe for in the header (admittedly only 15 words on 64-bit
  architectures...)

WS status