Re: Truncate in synchronous logical replication failed

On Mon, Apr 26, 2021 at 12:37 PM Japin Li <japinli(at)hotmail(dot)com> wrote:
>
> On Mon, 26 Apr 2021 at 12:49, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > On Fri, Apr 23, 2021 at 7:18 PM osumi(dot)takamichi(at)fujitsu(dot)com
> > <osumi(dot)takamichi(at)fujitsu(dot)com> wrote:
> >>
> >
> > The latest patch looks good to me. I have made a minor modification
> > and added a commit message in the attached. I would like to once again
> > ask whether anybody else thinks we should backpatch this? Just a
> > summary for anybody not following this thread:
> >
> > This patch fixes the Logical Replication of Truncate in synchronous
> > commit mode. The Truncate operation acquires an exclusive lock on the
> > target relation and indexes and waits for logical replication of the
> > operation to finish at commit. Now because we are acquiring the shared
> > lock on the target index to get index attributes in pgoutput while
> > sending the changes for the Truncate operation, it leads to a
> > deadlock.
> >
> > Actually, we don't need to acquire a lock on the target index as we
> > build the cache entry using a historic snapshot and all the later
> > changes are absorbed while decoding WAL. So, we wrote a special
> > purpose function for logical replication to get a bitmap of replica
> > identity attribute numbers where we get that information without
> > locking the target index.
> >
> > We are planning not to backpatch this as there doesn't seem to be any
> > field complaint about this issue since it was introduced in commit
> > 5dfd1e5a in v11.
>
> +1 for apply only on HEAD.
>

Seeing no other suggestions, I have pushed this in HEAD only. Thanks!

--
With Regards,
Amit Kapila.