Re: Fix an incorrect assertion condition in mdwritev().

Andres Freund <andres@anarazel.de>

From: Andres Freund <andres@anarazel.de>
To: Michael Paquier <michael@paquier.xyz>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Xing Guo <higuoxing@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-06-03T22:24:07Z
Lists: pgsql-hackers
Hi,

On 2024-06-04 07:17:51 +0900, Michael Paquier wrote:
> On Sun, May 26, 2024 at 12:08:46AM -0400, Tom Lane wrote:
> > After a few minutes' thought, how about:
> > 
> > 	Assert((uint64) blocknum + (uint64) nblocks <= (uint64) mdnblocks(reln, forknum));
> > 
> > This'd stop being helpful if we ever widen BlockNumber to 64 bits,
> > but I think that's unlikely.  (Partitioning seems like a better answer
> > for giant tables.)
> 
> No idea if this will happen or not, but that's not the only area where
> we are going to need a native uint128 implementation to control the
> overflows with uint64.

I'm confused - isn't using common/int.h entirely sufficient for that? Nearly
all architectures have more efficient ways to check for 64bit overflows than
doing actual 128 bit math.

Greetings,

Andres Freund



Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →
  1. Improve assertion in mdwritev()

  2. Provide vectored variants of smgrread() and smgrwrite().