Re: First draft of PG 17 release notes

On Thu, May 9, 2024 at 12:04 AM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> I have committed the first draft of the PG 17 release notes; you can
> see the results here:
>
> https://momjian.us/pgsql_docs/release-17.html

I had two comments:

--------
I think the read stream item:

"Allow the grouping of file system reads with the new system variable
io_combine_limit"

Might be better if it mentions the effect, like:

"Reduce system calls by automatically merging reads up to io_combine_limit"
-------
For the vacuum feature:

"Allow vacuum to more efficiently remove and freeze tuples"

I think that we need to more clearly point out the implications of the
feature added by Sawada-san (and reviewed by John) in 667e65aac35497.
Vacuum no longer uses a fixed amount of memory for dead tuple TID
storage and it is not preallocated. This affects users as they may
want to change their configuration (and expectations).

If you make that item more specific to their work, you should also
remove my name, as the work I did on vacuum this release was unrelated
to their work on dead tuple TID storage.

The work Heikki and I did which culminated in 6dbb490261 mainly has
the impact of improving vacuum's performance (vacuum emits less WAL
and is more efficient). So you could argue for removing it from the
release notes if you are using the requirement that performance
improvements don't go in the release notes.

However, one of the preliminary commits for this f83d70976 does change
WAL format. There are three WAL records which no longer exist as
separate records. Do users care about this?

- Melanie