Previously, any error reported by the backend while reading
system_constraints.sql would report the entire file, not just the
particular command it was working on. (Ask me how I know.) Likewise,
there were chunks of system_functions.sql that would be read as one
command, which would be annoying if anything failed there.
The issue for system_constraints.sql is an oversight in commit
dfb75e478. I didn't try to trace down where the poor formatting
in system_functions.sql started, but it's certainly contrary to
the advice at the head of that file.
Adopt the new pre-parsed representation for all built-in and
information_schema SQL-language functions, except for a small
number that can't presently be converted because they have
polymorphic arguments.
This eliminates residual hazards around search-path safety of
these functions, and might provide some small performance benefits
by reducing parsing costs. It seems useful also to provide more
test coverage for the SQL-standard-body feature.
Discussion: https://postgr.es/m/3956760.1618529139@sss.pgh.pa.us
Invent system_functions.sql to carry the function definitions that
were formerly in system_views.sql. The function definitions were
already a quarter of the file and are about to be more, so it seems
appropriate to give them their own home.
In passing, fix an oversight in dfb75e478: it neglected to call
check_input() for system_constraints.sql.
Discussion: https://postgr.es/m/3956760.1618529139@sss.pgh.pa.us
