Re: Direct I/O

On Sat, Apr 8, 2023 at 4:59 PM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> On Sat, Apr 8, 2023 at 4:47 PM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> > After a bit more copy-editing on docs and comments and a round of
> > automated indenting, I have now pushed this. I will now watch the
> > build farm. I tested on quite a few OSes that I have access to, but
> > this is obviously a very OS-sensitive kind of a thing.
>
> Hmm. I see a strange "invalid page" failure on Andrew's machine crake
> in 004_io_direct.pl. Let's see what else comes in.

No particular ideas about what happened there yet. It *looks* like we
wrote out a page, and then read it back in very soon afterwards, all
via the usual locked bufmgr/smgr pathways, and it failed basic page
validation. The reader was a parallel worker, because of the
debug_parallel_mode setting on that box. The page number looks
reasonable (I guess it's reading a page created by the UPDATE full of
new tuples, but I don't know which process wrote it). It's also not
immediately obvious how this could be connected to the 32 pinned
buffer problem (all that would have happened in the CREATE TABLE
process which ended already before the UPDATE and then the SELECT
backends even started).

Andrew, what file system and type of disk is that machine using?