ERROR: tuple concurrently updated when modifying privileges

[nickb]

Hello, hackers

we witnessed this slightly misleading error in production and it took us a 
while to figure out what was taking place.
Below are reproduction steps:


-- setup
create table trun(cate int4);

-- session 1
begin;
truncate table trun;

-- session 2
grant insert on table trun to postgres;

-- session 1
end;

-- session 2:
ERROR: XX000: tuple concurrently updated
LOCATION: simple_heap_update, heapam.c:4474

Apparently the tuple in question is the pg_class entry of the table being 
truncated. I didn't look too deep into the cause, but I'm certain the error 
message could be improved at least.

Regards,
Nick.

Re: PG 12 draft release notes

[nickb]

On Sat, May 11, 2019, at 22:33, Bruce Momjian wrote:
> http://momjian.us/pgsql_docs/release-12.html

There is a typo in E.1.3.1.1.:
> Expressions are evaluated at table partitioned table creation time.
First "table" seems to be excessive.

Regards,
Nick.