Re: Add sub-transaction overflow status in pg_stat_activity

On Tue, Dec 7, 2021 at 11:11 AM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:

>
> You added this to pg_stat_activity, which already has a lot of fields.
> We talked a few months ago about not adding more fields that weren't commonly
> used.
> https://www.postgresql.org/message-id/flat/20210426191811.sp3o77doinphyjhu%40alap3.anarazel.de#d96d0a116f0344301eead2676ea65b2e
>
> Since I think this field is usually not interesting to most users of
> pg_stat_activity, maybe this should instead be implemented as a function like
> pg_backend_get_subxact_status(pid).
>
> People who want to could use it like:
> SELECT * FROM pg_stat_activity psa, pg_backend_get_subxact_status(pid) sub;

I have provided two function, one for subtransaction counts and other
whether subtransaction cache is overflowed or not, we can use like
this, if we think this is better way to do it then we can also add
another function for the lastOverflowedXid

postgres[43994]=# select id, pg_stat_get_backend_pid(id) as pid,
pg_stat_get_backend_subxact_count(id) as nsubxact,
pg_stat_get_backend_subxact_overflow(id) as overflowed from
pg_stat_get_backend_idset() as id;
id | pid | nsubxact | overflowed
----+-------+----------+------------
1 | 43806 | 0 | f
2 | 43983 | 64 | t
3 | 43994 | 0 | f
4 | 44323 | 22 | f
5 | 43802 | 0 | f
6 | 43801 | 0 | f
7 | 43804 | 0 | f
(7 rows)

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com