[ZODB-Dev] non-transactional undo

[Barry Warsaw]

On Tue, 2003-06-17 at 09:00, Toby Dickenson wrote:

> I dont think it checksums the whole file, and a non-transactional undo might 
> have only changed a byte right at the start.
> 
> If it does have to read the whole file to md5 it, then I think that 
> disqualifies it as an *incremental* backup ;-)

Every time repozo adds to a backup (either with a full or an
incremental), it checksums the backup file and records the byte range
that the backup covers.  In slow mode, it does indeed go through each
backup file for the last cycle (i.e. the full and all the incrementals)
and verifies the md5 checksum for each chunk.  If there's a difference,
it refuses to do an incremental.  I still think it's valid to call this
an incremental because the file that it (eventually <wink>) writes only
contains the data from the last backed up chunk to the last completed
transaction written.

repozo will also check file sizes and do full backups when its shrunk
(most likely due to packs).

In -Q/--quick mode, only the last incremental chunk is md5 checksummed.

At least, this is how it's supposed to work.  It could probably use more
testing.

-Barry