Re: BUG #18280: logical decoding build wrong snapshot for subtransactions

Thank you for your correction.

> On Jan 24, 2024, at 17:18, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> While looking closely at the test result, I wondered how the following
> part of test "s0_begin" "s0_truncate" "s1_checkpoint" "s1_get_changes"
> "s0_insert_part" "s1_get_changes" "s0_commit" can see the insert when
> the containing transaction is not yet committed. Then, I found it is
> because the insert is performed from session 1 due to way it is
> declared.
>
> session "s1"
> ...
> step "s1_get_changes" { SELECT data FROM
> pg_logical_slot_get_changes('isolation_slot', NULL, NULL,
> 'skip-empty-xacts', '1', 'include-xids', '0'); }
> +step "s0_insert_part" { INSERT INTO tbl1_part VALUES (1); }
>
> I think this session should be performed from seesion-1 and we need
> one more get_changes() call to see the problem. I have modified the
> test accordingly and also changed the comments. See the attached and
> let me know what you people think.

I'm very sorry for confusing you due to my mistake. In my original patch,
"s0_insert_part" should be "s1_insert_part" in session "s1", and after
confirmation, the problem can be reproduced.
Of course your fix is totally correct for me.

Best Regards,
Fei Changhong
Alibaba Cloud Computing Ltd.