Re: Apply worker fails if a relation is missing on subscriber even if refresh publication has not been refreshed yet

Hi Amit,

Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, 23 Ara 2022 Cum, 09:39 tarihinde
şunu yazdı:

> I also have the same understanding but I think if we skip replicating
> some table due to the reason that the corresponding publication has
> not been refreshed then it is better to LOG that information instead
> of silently skipping it.

By skipping it, I mean the apply worker does not try to do anything with
the changes for the missing table since the worker simply cannot apply it
and only fails.
But I agree with you about logging it, the patch currently logs such cases
as warnings instead of errors.
I can make it LOG instead of WARNING, just wanted to make something
different than ERROR.

Do you have any use case in mind where the user has added a table to
> the publication even though she doesn't want it to be replicated? One
> thing that came to my mind is that due to some reason after adding a
> table to the publication, there is some delay in creating the table on
> the subscriber and then refreshing the publication and during that
> time user expects replication to proceed smoothly. But for that isn't
> it better that the user completes the setup on the subscriber before
> performing operations on such a table? Because say there is some error
> in the subscriber-side setup that the user misses then it would be a
> surprise for a user to not see the table data. In such a case, an
> ERROR/LOG information could be helpful for users.
>

I don't really see a specific use case for this. The delay between creating
a table on publisher and then on subscriber usually may not be even
that long to hurt anything. It just seems unnecessary to me that apply
worker goes into a failure loop until someone creates the table on the
subscriber, even though the table will not be replicated immediately.

Users also shouldn't expect for such tables to be replicated if they did
not refresh the publication. That will not happen with or without this
change. So I don't think it would be a surprise when they see their new
table has not been replicated yet. This issue will also be visible in the
logs, just not as an error.
And if users decide/remember to refresh the publication, they cannot do
that anyway if the table is still missing on the subscriber. So the REFRESH
PUBLICATION command will fail and then users will see an error log.

Best,
--
Melih Mutlu
Microsoft