zlib/gzip + anydbm or ...

[Jeremy Yallop]

* James T. Dennis
| Is there an obvious and simple way to use the existing standard
| libraries to support transparently compressed dbm files?
| 
| (Any combination of zlib/gzip etc with any of the dbm files would
| be considered).

I've done something similar to this before using dbhash/gdbm and zlib.

The code was something like:

import dbhash, zlib, tempfile

   if file_exists(filename):
       dbfile = open(filename)
       tmpfilename = tempfile.mktemp()
       temporary_file = open(tmpfilename, 'w')
       
       temporary_file.write(zlib.decompress(dbfile.read()))
       temporary_file.flush()
       dbfile.close()

       db = dbhash.open(tmpfilename, mode)

with code to recompress the file when the database is closed.

It worked fairly well, but I was only using it for fairly small files
(20 megabytes or less).

If you'd like the full code (around 180 lines) contact me by email.

Jeremy.