Re: Switching XLog source from archive to streaming when primary available

On Thu, Sep 15, 2022 at 1:52 PM Kyotaro Horiguchi
<horikyota(dot)ntt(at)gmail(dot)com> wrote:
>
> At Thu, 15 Sep 2022 10:28:12 +0530, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote in
> > I'm attaching the v6 patch that's rebased on to the latest HEAD.
> > Please consider this for review.
>
> Thaks for the new version!
>
> +#define StreamingReplRetryEnabled() \
> + (streaming_replication_retry_interval > 0 && \
> + StandbyMode && \
> + currentSource == XLOG_FROM_ARCHIVE)
>
> It seems to me a bit too complex..

I don't think so, it just tells whether a standby is allowed to switch
source to stream from archive.

> + /* Save the timestamp at which we're switching to archive. */
> + if (StreamingReplRetryEnabled())
> + switched_to_archive_at = GetCurrentTimestamp();
>
> Anyway we are going to open a file just after this so
> GetCurrentTimestamp() cannot cause a perceptible degradation.
> Coulnd't we do that unconditionally, to get rid of the macro?

Do we really need to do it unconditionally? I don't think so. And, we
can't get rid of the macro, as we need to check for the current
source, GUC and standby mode. When this feature is disabled, it
mustn't execute any extra code IMO.

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com