RE: Optionally automatically disable logical replication subscriptions on error

On Monday, December 6, 2021 1:38 PM Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com> wrote:
> > On Dec 1, 2021, at 8:48 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > The patch disables the subscription for non-transient errors. I am not
> > sure if we can easily make the call to decide whether any particular
> > error is transient or not. For example, DISK_FULL or OUT_OF_MEMORY
> > might not rectify itself. Why not just allow to disable the
> > subscription on any error? And then let the user check the error
> > either in view or logs and decide whether it would like to enable the
> > subscription or do something before it (like making space in disk, or
> > fixing the network).
>
> The original idea of the patch, back when I first wrote and proposed it, was to
> remove the *absurdity* of retrying a transaction which, in the absence of
> human intervention, was guaranteed to simply fail again ad infinitum.
> Retrying in the face of resource errors is not *absurd* even though it might fail
> again ad infinitum. The reason is that there is at least a chance that the
> situation will clear up without human intervention.
In my humble opinion, I felt the original purpose of the patch was to partially remedy
the situation that during the failure of apply, the apply process keeps going
into the infinite error loop.

I'd say that in this sense, if we include such resource errors, we fail to achieve
the purpose in some cases, because of some left possibilities of infinite loop.
Disabling the subscription with even one any error excludes this irregular possibility,
since there's no room to continue the infinite loop.

Best Regards,
Takamichi Osumi