Re: AIO v2.5

Hi,

On 2025-03-25 09:15:43 -0700, Noah Misch wrote:
> On Tue, Mar 25, 2025 at 11:57:58AM -0400, Andres Freund wrote:
> > FWIW, I prototyped this, it's not hard.
> >
> > But it can't replace the current WARNING with 100% fidelity: If we read 60
> > blocks in a single smgrreadv, we today would would emit 60 WARNINGs. But we
> > can't encode that many block offset in single PgAioResult, there's not enough
> > space, and enlarging it far enough doesn't seem to make sense either.
> >
> >
> > What we *could* do is to emit one WARNING for each bufmgr.c smgrstartreadv(),
> > with that warning saying that there were N zeroed blocks in a read from block
> > N to block Y and a HINT saying that there are more details in the server log.

It should probably be DETAIL, not HINT...

> Sounds fine.

I got that working. To make it readable, it required changing division of
labor between buffer_readv_complete() and buffer_readv_complete_one() a bit,
but I think it's actually easier to understand now.

Still need to beef up the test infrastructure a bit to make the multi-block
cases more easily testable.

Could use some input on the framing of the message/detail. Right now it's:

ERROR: invalid page in block 8 of relation base/5/16417
DETAIL: Read of 8 blocks, starting at block 7, 1 other pages in the same read are invalid.

But that doesn't seem great. Maybe:

DETAIL: Read of blocks 7..14, 1 other pages in the same read were also invalid.

But that still isn't really a sentence.

Greetings,

Andres Freund