Re: parallel append vs. simple UNION ALL

On Sat, Feb 24, 2018 at 2:55 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> 0001 is pretty much the same as the subquery-smarts.patch file I
> attached to the previous email. I don't see much reason not to go
> ahead and commit this, although it could use a test case. It makes
> the simple/flattened case work. After some study I think that the
> gather-parameter handling is correct, although if somebody felt like
> reviewing that portion especially I wouldn't say no.
>

I have applied 0001 on pg-head, and while playing with regression tests, it
crashed with below test case.

postgres=# SET min_parallel_table_scan_size=0;
SET
postgres=# SELECT * FROM information_schema.foreign_data_wrapper_options
ORDER BY 1, 2, 3;
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.

--logfile
2018-02-26 22:06:07.331 IST [43508] LOG: database system is ready to
accept connections
TRAP: FailedAssertion("!(subpath->parallel_safe)", File: "pathnode.c",
Line: 1813)
2018-02-26 22:06:42.345 IST [43508] LOG: server process (PID 43519) was
terminated by signal 6: Aborted
2018-02-26 22:06:42.345 IST [43508] DETAIL: Failed process was running:
SELECT * FROM information_schema.foreign_data_wrapper_options ORDER BY 1,
2, 3;

Thanks & Regards,
Rajkumar Raghuwanshi
QMG, EnterpriseDB Corporation