Re: Regarding huge logical slot lag between source and target

On Sun, 18 Oct, 2026, 22:52 Laurenz Albe, <laurenz(dot)albe(at)cybertec(dot)at> wrote:

> On Sun, 2026-10-18 at 19:49 +0530, Durgamahesh Manne wrote:
> > Logical slot lag 330GB on source grows faster during the huge
> modifications but it should be minimized which is not happened when load
> goes down.
> >
> > What is the action need to take for minimizing the lag to normal state.
> > Source version 16
> > Target version 16
> > Sufficient resources allocated and tuned replication related parameters
>
> ALTER SUBSCRIPTION sub SET (streaming = parallel);
>
> Also, set the following parameters to generous values (as your hardware
> allows):
>
> On the publisher:
>
> logical_decoding_work_mem
>
> On the subscriber:
>
> max_logical_replication_workers
> max_worker_processes
> max_parallel_apply_workers_per_subscription
> max_sync_workers_per_subscription
>
> Note the dependencies: max_worker_processes must accommodate for all the
> worker processes.
>
> Yours,
> Laurenz Albe
>

Hi
I already set those params with required values to make server running
smoothly

Alter subscription also done with binary and streaming options

Finally I could not find root cause what has caused to increase of that
much lag.

No long running queries at source
No blocking at target
Generally what might be reason to huge lag in terms of hundreds which can't
go down.

This is very rare situation we face an issue like this

As final decision I resync data from scratch.
Regards
Durga Mahesh

>