Re: How is this possible "publication does not exist"

On Thu, Jun 2, 2022 at 9:11 AM operations i <ioperations(dot)c(at)gmail(dot)com> wrote:

> sorry, I still confused ,as we have already created the publication
> "pub_test" , but during database runtime, function GetPublicationByName()
> does not get system catalog cache, Is there any mechanism that could make
> system catalog expand or shrink?
>

The system catalog doesn't expand or shrink in this case but rather it uses
a snapshot to check the visibility of rows present. Here, we use historic
snapshots to check the visibility of the publication row. Even though it is
present in the catalog, it won't be visible, so you are getting an error.
Here, the snapshot is built from WAL starting from the point where you
created a slot. As the publication is created after Insert when you are
trying to decode Insert, the required publication is not visible and hence
you are getting the error. You might want to read
src/backend/replication/logical/snapbuild.c to understand how the required
snapshots are built from WAL.

--
With Regards,
Amit Kapila.