Thread

RE: doc: update the default of data checksums in the doc of pg_rewind

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com> — 2025-12-25T03:16:34Z

On Thursday, December 25, 2025 11:14 AM Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com> wrote:
> On Thursday, December 25, 2025 8:22 AM Chao Li <li.evan.chao@gmail.com>
> wrote:
> >
> > > On Dec 24, 2025, at 15:27, Zhijie Hou (Fujitsu)
> > > <houzj.fnst@fujitsu.com>
> > wrote:
> > >
> > > Hi,
> > >
> > > I noticed that the pg_rewind documentation still states that data
> > > checksums is disabled by default, but it has been changed to on since
> PG18.
> > >
> > > Here's a small patch to update this.
> > >
> > > Best Regards,
> > > Hou zj
> > > <v1-0001-Fix-outdated-doc-in-pg_rewind.patch>
> >
> >
> > ```
> > -   the cluster was initialized with <application>initdb</application>.
> Neither
> > of these
> > -   are currently on by default.  <xref linkend="guc-full-page-writes"/>
> > -   must also be set to <literal>on</literal>, but is enabled by default.
> > +   the cluster was initialized with <application>initdb</application>
> > + (the
> > latter
> > +   being the default).  <xref linkend="guc-full-page-writes"/> must also be
> set
> > +   to <literal>on</literal>, but is enabled by default.
> > ```
> >
> > I think we can explicitly mention PG18 and later, like:
> > ```
> > the cluster was initialized with <application>initdb</application>
> > (data checksums are enabled by default in PostgreSQL 18 and later).
> > ```
> >
> > I searched over the docs, the usage of “<version> and later” is not
> > rare, for
> > example:
> > ```
> >   <para>
> >    <application>pg_amcheck</application> is designed to work with
> >    <productname>PostgreSQL</productname> 14.0 and later.
> >   </para>
> > ```
> 
> I think including a version number here is necessary, as pg_rewind is not
> compatible with older PostgreSQL versions. It should be the release notes of
> PostgreSQL 18 to reflect changes in default values, rather than the pg_rewind
> doc mentioning a behavior change. (We don't mention version number in
> initdb's doc as well)

Sorry, a typo above, 'necessary' -> 'unnecessary'.

Best Regards,
Hou zj