Re: parallel explain analyze support not exercised

On Mon, Apr 3, 2017 at 1:53 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> Please find the attached for the same.
>
>> +-- to increase the parallel query test coverage
>> +EXPLAIN (analyze, timing off, summary off, costs off) SELECT * FROM tenk1;
>> + QUERY PLAN
>> +-------------------------------------------------------------
>> + Gather (actual rows=10000 loops=1)
>> + Workers Planned: 4
>> + Workers Launched: 4
>> + -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
>> +(4 rows)
>
> Is there an issue that we might not actually be able to start all four
> workers? Serious question, not rhetorical.

If this is 'make check', then we should have 8 parallel workers
allowed, so if we only do one of these at a time, then I think we're
OK. But if somebody changes that configuration setting or if it's
'make installcheck', then the configuration could be anything.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company