Re: synchronized_standby_slots behavior inconsistent with quorum-based synchronous replication

[Ashutosh Sharma]

Hi Shveta,

Thanks again for your review comments and suggestions. Please see my
comments inline below:

On Wed, Jun 10, 2026 at 12:16 PM shveta malik <shveta.ma...@gmail.com> wrote:
>
> Please find a few comments on June8 version fo patches:
>
> 1)
> patch001:
>
> SYNC_REP_DEFAULT: do we need to give one-line comment for this
> somewhere as unlike PRIORITY and QUORUM, it is not self-explanatory.
>

Yes, it does makes sense to include a one-line comment. I've added it
in the attached patch.

>
> patch002:
> 2)
> It is better to avoid mentioning it as 'synchronized standby slots'.
> We can make it as 'synchronized_standby_slots' in below comments:
>
> + /* Parse the synchronized standby slots configuration */
>
> + * Report problem states for synchronized standby slots that prevented the
>

Good point. I've made the suggested change in the attached patch

> 3)
> For these error-messages too, we  need to mention GUC name to give
> better clarity.
>
> + GUC_check_errmsg("number of synchronized standby slots (%d) must not
> exceed the number of unique listed slots (%d)",
> + syncrep_parse_result->num_sync,
> + syncrep_parse_result->nmembers);
>
>
> How about:
> GUC_check_errcode(ERRCODE_INVALID_PARAMETER_VALUE);
> GUC_check_errmsg("invalid value for parameter \"%s\: synchronization
> requirement (%d) exceeds the number of unique listed slots (%d)",
>                  "synchronized_standby_slots",
>                  syncrep_parse_result->num_sync,
>                  syncrep_parse_result->nmembers);
>

Updated as suggested in the attached patch.

> 3)
> + GUC_check_errmsg("number of synchronized standby slots (%d) must be
> greater than zero",
> + syncrep_parse_result->num_sync)
>
> How about:
> GUC_check_errcode(ERRCODE_INVALID_PARAMETER_VALUE);
> GUC_check_errmsg("invalid value for parameter \"%s\: required number
> of synchronized standby slots (%d) must be greater than zero",
>                  "synchronized_standby_slots",
>                  syncrep_parse_result->num_sync);
>
>
>

Updated as suggested in the attached patch.

> 4)
> +ReportUnavailableSyncStandbySlots(SyncStandbySlotsStateInfo * slot_states
>
> We can get rid of space before slot_states. I think pgindent might
> have put it in my patch. Sorry for the trouble.
>
> 5)
> 003:
> - wait_for_all = (required == synchronized_standby_slots_config->nslotnames);
> + wait_for_all =
> + (synchronized_standby_slots_config->syncrep_method == SYNC_REP_DEFAULT);
>
> This change can be moved to 002, right?

Done.

PFA patch containing all the above changes.

--
With Regards,
Ashutosh Sharma.

0003-Add-FIRST-N-and-N-.-priority-syntax-to.patch
Description: Binary data

0002-Add-ANY-N-semantics-to-synchronized_standby_slots.patch
Description: Binary data

0001-Refactor-syncrep-parsing-to-represent-bare-standby-l.patch
Description: Binary data