Re: Reducing power consumption on idle servers

On Wed, Nov 16, 2022 at 2:34 PM Simon Riggs
<simon.riggs@enterprisedb.com> wrote:
>
> Reposting v6 now so that patch tester doesn't think this has failed
> when the patch on other thread gets applied.

Intention of the patch, that is, to get rid of promote_trigger_file
GUC sometime in future, looks good to me. However, the timeout change
to 60 sec from 5 sec seems far-reaching. While it discourages the use
of the GUC, it can impact many existing production servers that still
rely on promote_trigger_file as it can increase the failover times
impacting SLAs around failover.

How about retaining 5 sec as-is and adding a WARNING in
promote_trigger_file check/assign and in show GUC, in
CheckForStandbyTrigger() whenever PromoteTriggerFile is detected and
specifying about the depreciation in GUC's description?

+                     * to react to a trigger file.  Direct use of trigger file
+                     * is now deprecated and the promote_trigger_file will be
+                     * removed in a later release.
I think, adding 'Direct use of trigger file .....' in a next line that
starts with XXX (typically, this represents a TODO item) is good, no?

Also, do we need to add a TODO in postgresql wiki
(https://wiki.postgresql.org/wiki/Todo), possibly under a new section
'Deprecated Features' or 'Features To-Be-Removed In Near Future' or
some other (hm, it seems too vague, but it starts to track such
deprecated items), to not miss on removing the promote_trigger_file in
future releases?

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