Обсуждение: Way to check for function existance

Sorry if this has been covered before, but the mailing list search is
down right now.

What's the best way to check for the existance of a function? I saw
pg_function_is_visible(), but the problem is that I'd need to use
::regprocedure with it, and ::regprocedure generates an error if the
function doesn't exist. Since I can't trap the error in pgplsql that's
no use.

I'm also working on trying to do a select out of pg_proc, but I'm not
having a lot of luck there either...

# select oid,* from pg_proc where proname='user_write_lock_oid' and
 proargtypes = ARRAY((SELECT oid FROM pg_type WHERE
 typname='oid'))::oidvector;
ERROR:  cannot cast type oid[] to oidvector

--
Jim C. Nasby, Database Consultant               decibel@decibel.org
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"Jim C. Nasby" <decibel@decibel.org> writes:
> I'm also working on trying to do a select out of pg_proc, but I'm not
> having a lot of luck there either...

> # select oid,* from pg_proc where proname='user_write_lock_oid' and
>  proargtypes = ARRAY((SELECT oid FROM pg_type WHERE
>  typname='oid'))::oidvector;
> ERROR:  cannot cast type oid[] to oidvector

For standard types like OID, it's probably easiest just to hardwire the
oidvector value:
select ...
where proname='user_write_lock_oid' and pronargs = 1 and proargtypes = '26';
Note you should include the pronargs test to allow this to match the
index on pg_proc.

            regards, tom lane