Horton

Re: PG 13 release notes, first draft

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2020-05-08T04:22:02Z
Lists: pgsql-hackers 
On Thu, May 07, 2020 at 09:38:34AM -0400, Bruce Momjian wrote:
> On Wed, May  6, 2020 at 10:20:57PM -0700, Noah Misch wrote:
> > On Wed, May 06, 2020 at 07:40:25PM -0400, Bruce Momjian wrote:
> > > On Tue, May  5, 2020 at 11:39:10PM -0700, Noah Misch wrote:
> > > > On Mon, May 04, 2020 at 11:16:00PM -0400, Bruce Momjian wrote:
> > > > > Allow skipping of WAL for new tables and indexes if wal_level is 'minimal' (Noah Misch)
> > > > 
> > > > Kyotaro Horiguchi authored that one.  (I committed it.)  The commit message
> > > > noted characteristics, some of which may deserve mention in the notes:
> > > 
> > > Fixed.
> > 
> > I don't see that change pushed (but it's not urgent).
> 
> I got stuck on Amit's partition items and my head couldn't process any
> more, so I went to bed, and just committed it now.  I was afraid to have
> pending stuff uncommitted, but I am also hesitant to do a commit for
> each change.

Got it, +1 for batching such changes.

> > > > - Crash recovery was losing tuples written via COPY TO.  This fixes the bug.
> > > 
> > > This was not backpatched?
> > 
> > Right.
> 
> Oh.  So you are saying we could lose COPY data on a crash, even after a
> commit.  That seems bad.  Can you show me the commit info?  I can't find
> it.

commit c6b9204
Author:     Noah Misch <noah@leadboat.com>
AuthorDate: Sat Apr 4 12:25:34 2020 -0700
Commit:     Noah Misch <noah@leadboat.com>
CommitDate: Sat Apr 4 12:25:34 2020 -0700

    Skip WAL for new relfilenodes, under wal_level=minimal.
    
    Until now, only selected bulk operations (e.g. COPY) did this.  If a
    given relfilenode received both a WAL-skipping COPY and a WAL-logged
    operation (e.g. INSERT), recovery could lose tuples from the COPY.  See
    src/backend/access/transam/README section "Skipping WAL for New
    RelFileNode" for the new coding rules.  Maintainers of table access
    methods should examine that section.
    
    To maintain data durability, just before commit, we choose between an
    fsync of the relfilenode and copying its contents to WAL.  A new GUC,
    wal_skip_threshold, guides that choice.  If this change slows a workload
    that creates small, permanent relfilenodes under wal_level=minimal, try
    adjusting wal_skip_threshold.  Users setting a timeout on COMMIT may
    need to adjust that timeout, and log_min_duration_statement analysis
    will reflect time consumption moving to COMMIT from commands like COPY.
    
    Internally, this requires a reliable determination of whether
    RollbackAndReleaseCurrentSubTransaction() would unlink a relation's
    current relfilenode.  Introduce rd_firstRelfilenodeSubid.  Amend the
    specification of rd_createSubid such that the field is zero when a new
    rel has an old rd_node.  Make relcache.c retain entries for certain
    dropped relations until end of transaction.
    
    Bump XLOG_PAGE_MAGIC, since this introduces XLOG_GIST_ASSIGN_LSN.
    Future servers accept older WAL, so this bump is discretionary.
    
    Kyotaro Horiguchi, reviewed (in earlier, similar versions) by Robert
    Haas.  Heikki Linnakangas and Michael Paquier implemented earlier
    designs that materially clarified the problem.  Reviewed, in earlier
    designs, by Andrew Dunstan, Andres Freund, Alvaro Herrera, Tom Lane,
    Fujii Masao, and Simon Riggs.  Reported by Martijn van Oosterhout.
    
    Discussion: https://postgr.es/m/20150702220524.GA9392@svana.org

Commits

  1. Doc: improve release notes' info about FROM UNPACKAGED feature removal.

  2. Doc: fix misstatement in v13 release notes.

  3. Doc: some more v13 release note tweaking.

  4. Doc: update v13 release notes through today, do a copy-editing pass.

  5. Doc: fill in "major enhancements" list in v13 release notes.

  6. doc: PG 13 relnotes: fix typos

  7. doc: PG 13 relnotes, update TOAST item to mention decompression

  8. pgbench: document that the default data loading is client-side

  9. psql \d: Display table where trigger is defined, if inherited

  10. Skip WAL for new relfilenodes, under wal_level=minimal.

  11. Introduce vacuum errcontext to display additional information.

  12. Fix lquery's behavior for consecutive '*' items.

  13. Improve the internal implementation of ereport().

  14. Add object names to partition integrity violations.

  15. Allow page lock to conflict among parallel group members.

  16. Allow relation extension lock to conflict among parallel group members.

  17. Introduce "anycompatible" family of polymorphic types.

  18. Improve checking of child pages in contrib/amcheck.

  19. doc: Add information about new SQL part SQL/MDA

  20. Added relation name in error messages for constraint checks.

  21. Avoid full scan of GIN indexes when possible

  22. Use carriage returns for data insertion logs in pgbench on terminal

  23. Use memcpy instead of a byte loop in pglz_decompress

  24. Add backtrace support for error reporting

  25. Improve pruning of a default partition

  26. Improve psql's \d output for partitioned indexes.

  27. initdb: Change authentication defaults