Re: pg_logical_slot_peek_changes crashes postgres when called from inside pl/pgsql

> On Oct 6, 2017, at 4:21 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> 
> I wrote:
>> I thought of a better way, as attached.
> 
> Pushed.  Ben, could you confirm that the committed patch fixes your
> original use-case?  The 9.5 version of the patch is at
> 
> https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=13d2ed921035f2d88adf87d796373e920bdd56ee

Not quickly, to be honest. But the test case is not hard. If you can do this without crashing, I'm convinced you've fixed the problem as I've seen it:


SELECT * FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');

CREATE TABLE public.foo(i int);

insert into public.foo(i) values(1);

CREATE OR REPLACE FUNCTION logical_replication_slot_lsn_delta(slot text) RETURNS pg_lsn AS
$$
 BEGIN
     return location from pg_logical_slot_peek_changes(slot,null,1) limit 1;
 END
$$ language plpgsql;

select logical_replication_slot_lsn_delta('regression_slot');



Thanks for the fast response, and for the amazing code that is Postgres!