Re: Postgres-native method to identify if a tuple is frozen

On Mon, Jul 20, 2020 at 9:07 PM Lawrence Jones <lawrence(at)gocardless(dot)com> wrote:
>
>
> So we hit the question: how can we identify if a tuple is frozen? I know the tuple has both committed and aborted hint bits set, but accessing those bits seems to require superuser functions and are unlikely to be that fast.
>
> Are there system columns (similar to xmin, tid, cid) that we don't know about?
>

I think the way to get that information is to use pageinspect
extension and use some query like below but you are right that you
need superuser privilege for that:

SELECT t_ctid, raw_flags, combined_flags
FROM heap_page_items(get_raw_page('pg_class', 0)),
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2)
WHERE t_infomask IS NOT NULL OR t_infomask2 IS NOT NULL;

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com