Re: evtfoid and evtowner missing in findoidjoins/README

"Joel Jacobson" <joel(at)compiler(dot)org> writes:
> The below references are already properly documented in
> https://www.postgresql.org/docs/current/catalog-pg-event-trigger.html
> but missing in src/tools/findoidjoins/README.
> Join pg_catalog.pg_event_trigger.evtowner => pg_catalog.pg_authid.oid
> Join pg_catalog.pg_event_trigger.evtfoid => pg_catalog.pg_proc.oid

Yup, no surprise given the way findoidjoins works: it could only
discover those relationships if pg_event_trigger had some entries in
the end state of the regression database. Of course it doesn't, and
I'd be against leaving a live event trigger in place in that DB.
(I suspect there are other similar gaps in the coverage.)

I kind of wonder whether findoidjoins has outlived its purpose and
we should just remove it (along with the oidjoins test script).
IMO it was intended to find mistakes in the initial catalog data,
but given the current policy that the .dat files shall not contain
numeric OID references, that type of mistake is impossible anymore.
Certainly, it's been so long since that test script has caught
anything that it doesn't seem worth the annual-or-so maintenance
effort to update it.

A different line of thought would be to try to teach findoidjoins
to scrape info about catalog references out of catalogs.sgml, and
use that instead of or in addition to its current methods. That
seems like a fair amount of work though, and again I can't get
excited that it'd be worth the trouble.

Also, I recall mutterings on -hackers about adding foreign-key
entries to pg_constraint to document the catalog reference
relationships. (In my possibly-faulty recollection, the idea
was that these'd only be documentation and would lack enforcement
triggers; but perhaps we'd allow the planner to trust them for
purposes of optimizing multi-catalog queries.) If we had those,
we could make findoidjoins use them instead of trawling the data,
or maybe throw away findoidjoins per se and let the oidjoins.sql
script read the FK entries to find out what to check dynamically.

regards, tom lane