Re: patch to allow disable of WAL recycling

On 2018-Jul-10, Jerry Jelinek wrote:

> 2) Disabling WAL recycling reduces reliability, even on COW filesystems.

I think the problem here is that WAL recycling in normal filesystems
helps protect the case where filesystem gets full. If you remove it,
that protection goes out the window. You can claim that people needs to
make sure to have available disk space, but this does become a problem
in practice. I think the thing to do is verify what happens with
recycling off when the disk gets full; is it possible to recover
afterwards? Is there any corrupt data? What happens if the disk gets
full just as the new WAL file is being created -- is there a Postgres
PANIC or something? As I understand, with recycling on it is easy (?)
to recover, there is no PANIC crash, and no data corruption results.

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services