On Wed, Oct 30, 2024 at 2:42 PM Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> Vacuum currently counts and logs the number of pages of a relation
> with newly frozen tuples. It does not count the number of pages newly
> set all-frozen in the visibility map.
>
> The number of pages set all-frozen in the visibility map by a given
> vacuum can be useful when analyzing which normal vacuums reduce the
> number of pages future aggressive vacuum need to scan.
+1
Some small suggestions:
+ vmbits = visibilitymap_set(vacrel->rel, blkno, buf,
+ InvalidXLogRecPtr,
+ vmbuffer, InvalidTransactionId,
+ VISIBILITYMAP_ALL_VISIBLE |
+ VISIBILITYMAP_ALL_FROZEN);
How about using "old_vmbits" or something along the same lines to make
it clear that this value has the bits before visibilitymap_set()?
---
+ /* If it wasn't all-frozen before, count it */
+ if (!(vmbits & VISIBILITYMAP_ALL_FROZEN))
To keep consistent with surrounding codes in lazyvacuum.c, I think we
can write "if ((vmbits & VISIBILITYMAP_ALL_FROZEN) == 0)" instead.
Regards,
--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com
