I have a need for 64-bit BTrees (at least for IOBTree and OIBTree), and I'm not the first. I've created a feature development branch for this, and checked in my initial implementation. I've modified the existing code to use PY_LONG_LONG instead of int for the key and/or value type; there's no longer a 32-bit version in the modified code. Any Python int or long that can fit in 64 bits is accepted; ValueError is raised for values that require 65 bits (or more). Keys and values that can be reported as Python ints are, and longs are only returned when the value cannot be converted to a Python int. This can have a substantial effect on memory consumption, since keys and/or values now take twice the space. There may be performance issues as well, but those have not been tested. There are new unit tests, but more are likely needed. If you're interested in getting the code from Subversion, it's available at: svn://svn.zope.org/repos/main/ZODB/branches/fdrake-64bits/ Ideally, this or some variation on this could be folded back into the main development for ZODB. If this is objectionable, making 64-bit btrees available would require introducing new versions of the btrees (possibly named LLBTree, LOBTree, and OLBTree). I welcome comments. -Fred -- Fred L. Drake, Jr. <fdrake at gmail.com> "Don't let schooling interfere with your education." -- Mark Twain