Re: First draft of the PG 15 release notes

On Tue, May 10, 2022 at 08:31:17PM -0500, Justin Pryzby wrote:
> | Remove incorrect duplicate partition tables in system view pg_publication_tables (Hou Zhijie)
> 
> should say "partitions" ?
> "Do not show partitions whose parents are also published" (is that accurate?)

I went with:

    Remove incorrect duplicate partitions in system view
    pg_publication_tables (Hou Zhijie)

> | Allow system and TOAST B-tree indexes to efficiently store duplicates (Peter Geoghegan)
> | Previously de-duplication was disabled for these types of indexes. 
> 
> I think the user-facing change here is that (in addition to being "allowed"),
> it's now enabled by default for catalog indexes.  "Enable de-duplication of
> system indexes by default".

I went with:

    Enable system and TOAST B-tree indexes to efficiently store duplicates
    (Peter Geoghegan)

> | Prevent changes to columns only indexed by BRIN indexes from preventing HOT updates (Josef Simanek)
> 
> says "prevent" twice.
> "Allow HOT updates when changed columns are only indexed by BRIN indexes"
> (or "avoid precluding...")

I went with:

    Prevent changes to columns only indexed by BRIN indexes from
    disabling HOT updates (Josef Simanek)

> | Improve the performance of window functions that use row_number(), rank(), and count() (David Rowley)
> 
> The essential feature is a new kind of "prosupport", which is implemented for
> those core functions. I suggest to add another sentence about how prosupport
> can also be added to user-defined/non-core functions.

Uh, I don't see how "prosupport" would be relevant for users to know
about.

> | Store server-level statistics in shared memory (Kyotaro Horiguchi, Andres Freund, Melanie Plageman)
> 
> Should this be called "cumulative" statistics?  As in b3abca68106d518ce5d3c0d9a1e0ec02a647ceda.

Uh, they are counters, which I guess is cummulative, but that doesn't
seem very descriptive.  The documentation call it the statistics
collector, but I am not sure we even have that anymore with an in-memory
implementation.  I am kind of not sure what to call it.

> | Allows view access to be controlled by privileges of the view user (Christoph Heiss)
> 
> Allow

Fixed.

> | New function
> 
> "The new function .." (a few times)

Uh, I only see it once.

> | Improve the parallel pg_dump performance of TOAST tables (Tom Lane) 
> 
> I don't think this needs to be mentioned, unless maybe folded into an entry
> like "improve performance when dumping with many objects or relations with
> large toast tables".

I mentioned it because I thought users who tried parallelism might find
it is faster now so they should re-test it, no?

> | Allow pg_basebackup to decompress LZ4 and Zstandard compressed server-side base backups, and LZ4 and Zstandard
compressoutput files (Dipesh Pandit, Jeevan Ladhe) 
 
> 
> maybe: "... and to compress output files with LZ4 and Zstandard."

Yes, I like that better, done.

> |  Add direct I/O support to macOS (Thomas Munro)
> | This only works if max_wal_senders=0 and wal_level=minimal. 
> 
> I think this should mention that it's only for WAL.

Agreed, done.

> | Remove status reporting during pg_upgrade operation if the output is not a terminal (Andres Freund)
> 
> Maybe: "By default, do not output status information unless the output is a terminal"

I went with:

    Disable default status reporting during pg_upgrade operation if
    the output is not a terminal (Andres Freund)

> | Add new protocol message COMPRESSION and COMPRESSION_DETAIL to specify the compression method and level (Robert
Haas)
> 
> s/level/options/ ?

Ah, yes, this changed to be more generic than level, done.

> | Prevent DROP DATABASE, DROP TABLESPACE, and ALTER DATABASE SET TABLESPACE from occasionally failing during
concurrentuse on Windows (Thomas Munro)
 
> 
> Maybe this doesn't need to be mentioned ?

Uh, the previous behavior seems pretty bad so I wanted to mention it
will not happen anymore.

> | Fix pg_statio_all_tables to sum values for the rare case of TOAST tables with multiple indexes (Andrei Zubkov)
> | Previously such cases would have one row for each index. 
> 
> Doesn't need to be mentioned ?
> It doesn't seem like a "compatibility" issue anyway.

Uh, there were certain cases where multiple indexes happened and I think
we need to tell people it is no longer a problem to work around, no?

> Should this be included?
> 6b94e7a6da2 Consider fractional paths in generate_orderedappend_paths

I looked at that but didn't see how it would be relevent for users.  Do
you have a suggestion for text?

> Should any of these be listed as incompatible changes (some of these I asked
> before, but the others are from another list).
> 
> 95ab1e0a9db interval:  round values when spilling to months

Yes, moved already.

> 9cd28c2e5f1 Remove server support for old BASE_BACKUP command syntax.

Seems internal-only so moved to Source Code.

> 0d4513b6138 Remove server support for the previous base backup protocol.

Same.

> ccd10a9bfa5 Fix enforcement of PL/pgSQL variable CONSTANT markings (Tom Lane)

I didn't see not enforcing constant as an incompatibility, but rather a
bug.

> 38bfae36526 pg_upgrade: Move all the files generated internally to a subdirectory

I think since we have a pg_upgrade section, it seems better there.

> 376ce3e404b Prefer $HOME when looking up the current user's home directory.

Uh, I didn't think so.

> 7844c9918a4 psql: Show all query results by default

Same.

> 17a856d08be Change aggregated log format of pgbench.

We have a pgbench section and I can't see it. I am trying to keep
incompatiblities as things related to in-production problems or
surprises.

> ? 73508475d69 Remove pg_atoi()

I don't see who would care except for internals folks.

> ? aa64f23b029 Remove MaxBackends variable in favor of GetMaxBackends() function.

Same.

> ? d816f366bc4 psql: Make SSL info display more compact

I did look at that but considered that this wouldn't be something that
would break anything.

> ? 27b02e070fd pg_upgrade: Don't print progress status when output is not a tty.

Same.

> ? ab4fd4f868e Remove 'datlastsysoid'.

Seemed too internal.

Thanks for all these ideas!

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

  Indecision is a decision.  Inaction is an action.  Mark Batterson