Re: Fwd: Core dump with nested CREATE TEMP TABLE

Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
> On Sat, Sep 5, 2015 at 3:41 PM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> wrote:
>> I was about to test this and was verifying that the crash still worked
>> when I noticed this in the logs (9.4.1, not HEAD). Not sure if there's any
>> realion here or not...
>>
>> WARNING: relation "pg_proc" page 121 is uninitialized --- fixing
>> WARNING: relation "pg_proc" page 122 is uninitialized --- fixing

> [reading vacuumlazy.c...] This seems unrelated and I would not worry about
> it. Those system catalogs have been extended with new pages by a couple of
> backends, but a crash happened before they could actually insert tuples on
> it and commit. Perhaps you were creating a bunch of objects when a crash
> happened, no?

If this is the system you were doing the previous crash testing on, I'd
say it's a direct artifact of those crashes. You were repeatedly crashing
the system during transactions that created functions and temp tables,
which would surely make entries in pg_proc, pg_depend, etc. The crash
came before commit and so neither the relation pages nor the WAL entries
would necessarily get to disk. But extension of the relations to make
room would still happen. Moreover, there's probably nothing to cause
those new pages to get added to the relations' FSM, so each new test
attempt would add another set of pages. Eventually autovacuum would
notice, which is what you've got logged here, but it might take awhile.

regards, tom lane