Re: PG 13 release notes, first draft

On Thu, May 7, 2020 at 09:22:02PM -0700, Noah Misch wrote:
> On Thu, May 07, 2020 at 09:38:34AM -0400, Bruce Momjian wrote:
> > > > > - 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(at)leadboat(dot)com>
> AuthorDate: Sat Apr 4 12:25:34 2020 -0700
> Commit: Noah Misch <noah(at)leadboat(dot)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.

OK, so how do we want to document this? Do I mention in the text below
the WAL skipping item that this fixes a bug where a mix of simultaneous
COPY and INSERT into a table could lose rows during crash recovery, or
create a new item?

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EnterpriseDB https://enterprisedb.com

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