Re: pgsql: Add decoding of sequences to test_decoding

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.

Greetings,

Andres Freund