Re: [HACKERS] [PATCH]make pg_rewind to not copy useless WAL files

Greetings!

* chenhj (chjischj(at)163(dot)com) wrote:
> Rebased and removed the whitespace.

Thanks for working on this, I agree that it seems like a pretty cool
optimization for pg_rewind.

I've only read through the thread to try and understand what's going on
and the first thing that comes to mind is that you're changing
pg_rewind to not remove the WAL from before the divergence (split)
point, but I'm not sure why. As noted, that WAL isn't needed for
anything (it's from before the split, after all), so why keep it? Is
there something in this optimization that depends on the old WAL being
there and, if so, what and why?

That's also different from how pg_basebackup works, which I don't think
is good (seems like pg_rewind should operate in a pretty similar manner
to pg_basebackup).

Setting this back to Waiting for Author but hopefully you can reply soon
and clarify that, possibly adjusting the patch accordingly.

Thanks!

Stephen