Re: [POC] Faster processing at Gather node

On Fri, Nov 10, 2017 at 8:36 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Thu, Nov 9, 2017 at 9:31 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> Have you set force_parallel_mode=regress; before running the
>> statement?
>
> Yes, I tried that first.
>
>> If so, then why you need to tune other parallel query
>> related parameters?
>
> Because I couldn't get it to break the other way, I then tried this.
>
> Instead of asking me what I did, can you tell me what I need to do?
> Maybe a self-contained reproducible test case including exactly what
> goes wrong on your end?
>

I think we are missing something very basic because you should see the
failure by executing that statement in force_parallel_mode=regress
even in a freshly created database. I guess the missing point is that
I am using assertions enabled build and probably you are not (If this
is the reason, then it should have striked me first time). Anyway, I
am writing steps to reproduce the issue.

1. initdb
2. start server
3. connect using psql
4. set force_parallel_mode=regress;
5. Create Table as_select1 AS SELECT * FROM pg_class WHERE relkind = 'r';

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com