Triggers might be caching broken fmgr info

Try this with current sources:

Add this line

update pg_proc set prosrc = 'foobar' where proname = 'check_primary_key';

to the end of regress/sql/create_function_1.sql. (The function is created
earlier in this file.) This simulates the situation where the
Dynamic_library_path (under development) has become bad between creation
and use of a function.

Then run the regression tests (I ran installcheck). You will get a
segfault in the 'triggers' test which looks something like this:

DEBUG: StartTransactionCommand
DEBUG: query: insert into fkeys2 values (10, '1', 1);
DEBUG: ProcessQuery
ERROR: Can't find function foobar in file /home/peter/pgsql/src/test/regress/../../../contrib/spi/refint.so
DEBUG: AbortCurrentTransaction
DEBUG: StartTransactionCommand
DEBUG: query: insert into fkeys2 values (30, '3', 2);
DEBUG: ProcessQuery
pg-install/bin/postmaster: reaping dead processes...

The core file ends like this:

#0 0x7f7f7f7f in ?? ()
#1 0x80f01ad in ExecBRInsertTriggers (estate=0x82a14e8, rel=0x4035bb34,
trigtuple=0x82a1b0c) at trigger.c:900

(I don't know what the #0 is trying to tell me.)

My best guess is that the trigger fmgr lookup in trigger.c:846

if (trigger->tgfunc.fn_oid == InvalidOid)
fmgr_info(trigger->tgfoid, &trigger->tgfunc);

might be reading out of an incompletely initialized trigger->tgfunc
structure. This is supported by the fact that if I move the

finfo->fn_oid = functionId;

assignment in fmgr_info() to the very end of that function, this passes
gracefully (because the elog comes before the assignment).

This might even be a workable fix, but I'm wondering whether elog(ERROR)
should not flush the trigger cache.

--
Peter Eisentraut peter_e(at)gmx(dot)net http://funkturm.homeip.net/~peter