Re: Synchronizing slots from primary to standby

Hi,

On 11/28/23 4:13 AM, shveta malik wrote:
> On Mon, Nov 27, 2023 at 4:08 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>>
>> On Mon, Nov 27, 2023 at 2:27 PM Zhijie Hou (Fujitsu)
>> <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>>>
>>> Here is the updated version(v39_2) which include all the changes made in 0002.
>>> Please use for review, and sorry for the confusion.
>>>
>>
>> --- a/src/backend/replication/logical/launcher.c
>> +++ b/src/backend/replication/logical/launcher.c
>> @@ -8,20 +8,27 @@
>> * src/backend/replication/logical/launcher.c
>> *
>> * NOTES
>> - * This module contains the logical replication worker launcher which
>> - * uses the background worker infrastructure to start the logical
>> - * replication workers for every enabled subscription.
>> + * This module contains the replication worker launcher which
>> + * uses the background worker infrastructure to:
>> + * a) start the logical replication workers for every enabled subscription
>> + * when not in standby_mode.
>> + * b) start the slot sync worker for logical failover slots synchronization
>> + * from the primary server when in standby_mode.
>>
>> I was wondering do we really need a launcher on standby to invoke
>> sync-slot worker. If so, why? I guess it may be required for previous
>> versions where we were managing work for multiple slot-sync workers
>> which is also questionable in the sense of whether launcher is the
>> right candidate for the same but now with the single slot-sync worker,
>> it doesn't seem worth having it. What do you think?
>>
>> --
>
> Yes, earlier a manager process was needed to manage multiple slot-sync
> workers and distribute load among them, but now that does not seem
> necessary. I gave it a try (PoC) and it seems to work well. If there
> are no objections to this approach, I can share the patch soon.
>

+1 on this new approach, thanks!

Regards,

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