Re: [Patch] ALTER SYSTEM READ ONLY

On Thu, May 13, 2021 at 2:54 PM Amul Sul <sulamul(at)gmail(dot)com> wrote:
>
> On Thu, May 13, 2021 at 12:36 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> > On Wed, May 12, 2021 at 5:55 PM Amul Sul <sulamul(at)gmail(dot)com> wrote:
> > >
> >
> > Thanks for the updated patch, while going through I noticed this comment.
> >
> > + /*
> > + * WAL prohibit state changes not allowed during recovery except the crash
> > + * recovery case.
> > + */
> > + PreventCommandDuringRecovery("pg_prohibit_wal()");
> >
> > Why do we need to allow state change during recovery? Do you still
> > need it after the latest changes you discussed here, I mean now
> > XLogAcceptWrites() being called before sending barrier to backends.
> > So now we are not afraid that the backend will write WAL before we
> > call XLogAcceptWrites(). So now IMHO, we don't need to keep the
> > system in recovery until pg_prohibit_wal(false) is called, right?
> >
>
> Your understanding is correct, and the previous patch also does the same, but
> the code comment is wrong. Fixed in the attached version, also rebased for the
> latest master head. Sorry for the confusion.

Great thanks. I will review the remaining patch soon.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com