I reviewed the patch you submitted and identified two issues.
1.In the Add pg_stat_recovery system view patch file, the documentation
modification indicates that the lack of permissions only results in the inability
to view a few specific columns. But the implementation of the code is:
if (! has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS)) PG_RETURN_NULL();
If there is no permission, return an empty line. This is inconsistent with the written document.
Yeah, this is a mismatch in the patch v3. However, it's been removed by Michael in the commit. So it should be fine in HEAD.
2.In the function pg_stat_get_recovery(), the two arrays "Datum *values" and "bool *nulls" consist of a fixed set of seven elements, so there is no need for dynamic allocation.
For a single-row function with ~8–10 columns, saving one palloc is a micro-optimization, not a major performance issue. I am not that sure of the benefit it brings, still preparing a small patch to turn the palloc into a fixed stack array.
