Re: pgsql: Add decoding of sequences to test_decoding

On 2/12/22 23:04, Andres Freund wrote:
> Hi,
>
> On 2022-02-11 23:52:20 +0000, Tomas Vondra wrote:
>> Add decoding of sequences to test_decoding
>>
>> Commit 0da92dc530 improved the logical decoding infrastructure to handle
>> sequences, and did various changes to related parts (WAL logging etc.).
>> But it did not include any implementation of the new callbacks added to
>> OutputPluginCallbacks.
>>
>> This extends test_decoding with two callbacks to decode sequences. The
>> decoding of sequences may be disabled using 'include-sequences', a new
>> option of the output plugin.
>>
>> Author: Tomas Vondra, Cary Huang
>> Reviewed-by: Peter Eisentraut, Hannu Krosing, Andres Freund
>> Discussion: https://postgr.es/m/d045f3c2-6cfb-06d3-5540-e63c320df8bc@enterprisedb.com
>> Discussion: https://postgr.es/m/1710ed7e13b.cd7177461430746.3372264562543607781@highgo.ca
>
> The tests fail on slow machines (valgrind in this case), with some spurious
> output differences:
>
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2022-02-12%2010%3A24%3A22
>
> diff -U3 /mnt/resource/bf/build/skink-master/HEAD/pgsql/contrib/test_decoding/expected/sequence.out /mnt/resource/bf/build/skink-master/HEAD/pgsql.build/contrib/test_decoding/results/sequence.out
> --- /mnt/resource/bf/build/skink-master/HEAD/pgsql/contrib/test_decoding/expected/sequence.out 2022-02-12 00:40:25.431913374 +0000
> +++ /mnt/resource/bf/build/skink-master/HEAD/pgsql.build/contrib/test_decoding/results/sequence.out 2022-02-12 11:07:19.177487256 +0000
> @@ -263,12 +263,14 @@
> data
> -----------------------------------------------------------------------------------------
> BEGIN
> + COMMIT
> + BEGIN
> sequence public.test_table_a_seq: transactional:1 last_value: 1 log_cnt: 0 is_called:0
> sequence public.test_table_a_seq: transactional:1 last_value: 33 log_cnt: 0 is_called:1
> table public.test_table: INSERT: a[integer]:1 b[integer]:100
> table public.test_table: INSERT: a[integer]:2 b[integer]:200
> COMMIT
> -(6 rows)
> +(8 rows)
>
> I don't think it's a good idea to use skip-empty-xacts = 0 in tests, there
> always can be an autovacuum or such.
>

Thanks, I pushed a fix. Turns out the bug was a bit worse, because the
sequence callbacks did not actually deal with empty xacts correctly, so
I fixed that too.

regards

--
Tomas Vondra
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