Re: Using base backup exclusion filters to reduce data transferred with pg_rewind

On Sat, Mar 24, 2018 at 11:14:34PM -0400, Tom Lane wrote:
> Stephen Frost <sfrost@snowman.net> writes:
>> I don't completely buy off on the argument that having these #define's
>> would make it easier for forks (we've had quite a few folks fork PG, but
>> how many of them have actually changed "base"?) and I'm on the fence
>> about if these will make our lives simpler down the road when it comes
>> to changing the directory names
> 
> I am distressed that nobody, apparently, is putting any weight on the
> back-patching pain that will result from widespread replacement of path
> names with macros.  I don't buy that either we or anyone else will need
> to change these names in future, so I see pain and effectively no
> gain.

That's actually something I worry about as well (as the author!), which
is why I qualify the changes as intrusive.  At the end, I think that I
would be tempted to just do #3, aka to keep a copy of the filter list in
pg_rewind code while hardcoding a minimum of names and mention in both
basebackup.c and pg_rewind code to not forget to update the filter list
if necessary.  New paths in the data folder are not added on a monthly
basis either, and not all of them can be filtered out so that's easy to
maintain.
--
Michael