Re: per backend WAL statistics

On Wed, Feb 26, 2025 at 10:59:11AM +0000, Bertrand Drouvot wrote:
> Yup. That's what we've done in pg_stat_io_build_tuples() too (ff7c40d7fd6).
> Without this we'd get "2000-01-01 00:00:00+00" in the stats_reset field of
> pg_stat_get_backend_wal() and pg_stat_get_backend_io().

Right, forgot about this part.

> That was not needed for pg_stat_io and pg_stat_wal because the stats_reset field
> was already non null after initdb.

0001 was OK, so done.

In 0002, couldn't it be better to have the pg_stat_get_backend_stats()
static in pgstatfuncs.c? In 0003, pg_stat_get_backend_wal() is also
in pgstatfuncs.c, meaning that all the callers of
pg_stat_get_backend_stats() would be in this file.

-typedef struct PgStat_Backend
-{
- TimestampTz stat_reset_timestamp;
- PgStat_BktypeIO io_stats;
-} PgStat_Backend;
-
/* ---------
* PgStat_BackendPending Non-flushed backend stats.
* ---------

In 0003, let's keep PgStat_BackendPending grouped with PgStat_Backend,
so it sounds better to move both of them after the WAL stats
structures.
--
Michael