Re: PGPROC alignment (was Re: pgsql: Separate RecoveryConflictReasons from procsignals)

Hi,

On Tue, Feb 10, 2026 at 01:15:01PM -0500, Andres Freund wrote:
> Hi,
> 
> On 2026-02-10 19:14:44 +0200, Heikki Linnakangas wrote:
> Yea, I don't think we need to be perfect here. Just a bit less bad. And, as
> you say, the current order doesn't make a lot of sense.
> Just grouping things like
> - pid, pgxactoff, backendType (i.e. barely if ever changing)
> - wait_event_info, waitStart (i.e. very frequently changing, but typically
>   accessed within one proc)
> - sem, lwWaiting, waitLockMode (i.e. stuff that is updated frequently and
>   accessed across processes)

With an ordering like in the attached (to apply on top of Heikki's patch), we're
back to 832 bytes.

But, then the pg_attribute_aligned() added in Heikki's patch makes it 896 bytes...

"
/*    816      |      16 */    dlist_node lockGroupLink;
/* XXX 64-byte padding   */

                               /* total size (bytes):  896 */
                             }
"

What about applying this new ordering and remove the pg_attribute_aligned()? (I
thought the aligned attribute would be smarter than that and not add this 64 padding
bytes).

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com