Horton

Re: First draft of PG 17 release notes

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-05-15T01:00:50Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Revert support for ALTER TABLE ... MERGE/SPLIT PARTITION(S) commands

  2. When creating materialized views, use REFRESH to load data.

  3. Revert temporal primary keys and foreign keys

  4. Avoid needless large memcpys in libpq socket writing

  5. Enhance nbtree ScalarArrayOp execution.

  6. Introduce a non-recursive JSON parser

  7. Combine freezing and pruning steps in VACUUM

  8. Allow SIGINT to cancel psql database reconnections.

  9. Provide API for streaming relation data.

  10. Add hash support functions and hash opclass for contrib/ltree.

  11. Pull up ANY-SUBLINK with the necessary lateral support.

  12. Read WAL directly from WAL buffers.

  13. Introduce the dynamic shared memory registry.

  14. Add macros for looping through a List without a ListCell.

  15. Support +/- infinity in the interval data type.

  16. Extend ALTER OPERATOR to allow setting more optimization attributes.

  17. Consider cheap startup paths in add_paths_to_append_rel

On Tue, May 14, 2024 at 03:39:26PM -0400, Melanie Plageman wrote:
> On Thu, May 9, 2024 at 12:04 AM Bruce Momjian <bruce@momjian.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"

Uh, as I understand it, the reduced number of system calls is not the
value of the feature, but rather the ability to request a larger block
from the I/O subsystem.  Without it, you have to make a request and wait
for each request to finish.  I am open to new wording, but I am not sure
your new wording is accurate.

> -------
> 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?

I don't think users really care about these details, just that it is
faster so they will not be surprised if there is a change.  I was
purposely vague to group multiple commits into the single item.  By
grouping them together, I got enough impact to warrant listing it.  If
you split it apart, it is harder to justify mentioning them.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Only you can decide what is important to you.