Justin Pryzby <pryzby@telsasoft.com> writes:
> But Petr has a point - pg_upgrade should aspire to catch errors in --check,
> rather than starting and then leaving a mess behind for the user to clean up
Agreed; pg_upgrade has historically tried to find problems similar to
this. However, it's not just aggregates that are at risk. People
might also have built user-defined plain functions, or operators,
atop these functions. How far do we want to go in looking?
As for the query, I think it could be simplified quite a bit by
relying on regprocedure literals, that is something like
WHERE ... a.aggtransfn IN
('array_append(anyarray,anyelement)'::regprocedure,
'array_prepend(anyelement,anyarray)'::regprocedure,
...)
Not sure if it's necessary to stick explicit "pg_catalog." schema
qualifications into this --- IIRC pg_upgrade runs with restrictive
search_path, so that this would be safe as-is.
Also, I think you need to check aggfinalfn too.
Also, I'd be inclined to reject system-provided objects by checking
for OID >= 16384 rather than hard-wiring assumptions about things
being in pg_catalog or not.
regards, tom lane