Horton

Re: logical replication of truncate command with trigger causes Assert

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Mark Dilger <mark.dilger@enterprisedb.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Simon Riggs <simon.riggs@enterprisedb.com>
Date: 2021-06-10T04:10:04Z
Lists: pgsql-hackers 
On Wed, Jun 9, 2021 at 8:44 PM Mark Dilger <mark.dilger@enterprisedb.com> wrote:
>
> > On Jun 9, 2021, at 7:52 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >
> > Here's a draft patch for that.  I decided the most sensible way to
> > organize this is to pair the existing ensure_transaction() subroutine
> > with a cleanup subroutine.  Rather unimaginatively, perhaps, I renamed
> > it to begin_transaction_step and named the cleanup end_transaction_step.
> > (Better ideas welcome.)
>
> Thanks!  The regression test I posted earlier passes with this patch applied.
>

I have also read the patch and it looks good to me.

> > Somewhat unrelated, but ... am I reading the code correctly that
> > apply_handle_stream_start and related routines are using Asserts
> > to check that the remote sent stream-control messages in the correct
> > order?
> >

Yes. I think you are talking about Assert(!in_streamed_transaction).
There is no particular reason that such Asserts are required, so we
can change to test-and-elog as you suggested later in your email.

>  That seems many degrees short of acceptable.
>
> Even if you weren't reading that correctly, this bit:
>
>     xid = pq_getmsgint(s, 4);
>
>     Assert(TransactionIdIsValid(xid));
>
> simply asserts that the sending server didn't send an invalid subtransaction id.
>

This also needs to be changed to test-and-elog.

-- 
With Regards,
Amit Kapila.

Commits

  1. Don't use Asserts to check for violations of replication protocol.

  2. Rearrange logrep worker's snapshot handling some more.

  3. Restore the portal-level snapshot after procedure COMMIT/ROLLBACK.

  4. Logical replication support for TRUNCATE

  5. Logical replication support for initial data copy