Re: Draft back-branch release notes are up for review

On Fri, Jun 14, 2019 at 04:58:47PM -0400, Tom Lane wrote:
> https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=0995cefa74510ee0e38d1bf095b2eef2c1ea37c4

> +<!--
> +Author: Peter Geoghegan <pg@bowt.ie>
> +Branch: master [9b42e7137] 2019-05-13 10:27:59 -0700
> +Branch: REL_11_STABLE [bf78f50ba] 2019-05-13 10:27:57 -0700
> +-->
> +     <para>
> +      Avoid corruption of a btree index in the unlikely case that a failure
> +      occurs during key truncation during a page split (Peter Geoghegan)
> +     </para>

To me, this text implies a cautious DBA should amcheck every index.  Reading
the thread[1], I no longer think that.  It's enough to monitor that VACUUM
doesn't start failing persistently on any index.  I suggest replacing this
release note text with something like the following:

  Avoid writing erroneous btree index data that does not change query results
  but causes VACUUM to abort with "failed to re-find parent key".  Affected
  indexes are rare; REINDEX fixes them.

(I removed "key truncation during a page split" as being too technical for
release notes.)

[1] https://postgr.es/m/flat/CAH2-WzkcWT_-NH7EeL=Az4efg0KCV+wArygW8zKB=+HoP=VWMw@mail.gmail.com