delta copies

Matt McCutchen hashproduct+rsync at gmail.com
Sun Sep 23 16:09:15 GMT 2007


On 9/23/07, Robert Fitzpatrick <lists at webtent.net> wrote:
> On Sun, 2007-09-23 at 00:56 -0400, Matt McCutchen wrote:
> > Either the delta transfer algorithm is not being used due to a
> > misconfiguration, or the pgsql backups are changing in a perverse way
> > that prevents it from matching any data.

> Doing some more testing this morning, maybe what you suggested about the
> pgsql backup is what is happening.

The "perverse way" I mentioned would be along the lines of updating a
set of timestamps that appear every few hundred bytes in the backup
file, regardless of how many values in the database have actually
changed.  This would prevent any of the blocks into which rsync splits
the old destination file from matching the source file.

Matt


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