Re: WIP: WAL prefetch (another approach)

On Fri, Nov 26, 2021 at 9:47 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Yeah ... on the one hand, that machine has shown signs of
> hard-to-reproduce flakiness, so it's easy to write off the failures
> I saw as hardware issues. On the other hand, the flakiness I've
> seen has otherwise manifested as kernel crashes, which is nothing
> like the consistent test failures I was seeing with the patch.
>
> Andres speculated that maybe we were seeing a kernel bug that
> affects consistency of concurrent reads and writes. That could
> be an explanation; but it's just evidence-free speculation so far,
> so I don't feel real convinced by that idea either.
>
> Anyway, I hope to find time to see if the issue still reproduces
> with Thomas' new patch set.

Honestly, all the reasons that Thomas articulated for the revert seem
relatively unimpressive from my point of view. Perhaps they are
sufficient justification for a revert so near to the end of the
development cycle, but that's just an argument for committing things a
little sooner so we have time to work out the kinks. This kind of work
is too valuable to get hung up for a year or three because of a couple
of minor preexisting bugs and/or preexisting maybe-bugs.

--
Robert Haas
EDB: http://www.enterprisedb.com