Re: [HACKERS] why not parallel seq scan for slow functions

On Thu, Sep 14, 2017 at 3:19 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> The attached patch fixes both the review comments as discussed above.

This cost stuff looks unstable:

test select_parallel          ... FAILED

!  Gather  (cost=0.00..623882.94 rows=9976 width=8)    Workers Planned: 4
!    ->  Parallel Seq Scan on tenk1  (cost=0.00..623882.94 rows=2494 width=8) (3 rows)
 drop function costly_func(var1 integer);
--- 112,120 ---- explain select ten, costly_func(ten) from tenk1;                                  QUERY PLAN
----------------------------------------------------------------------------
!  Gather  (cost=0.00..625383.00 rows=10000 width=8)    Workers Planned: 4
!    ->  Parallel Seq Scan on tenk1  (cost=0.00..625383.00 rows=2500 width=8) (3 rows)
 drop function costly_func(var1 integer);

From https://travis-ci.org/postgresql-cfbot/postgresql/builds/277376953 .

-- 
Thomas Munro
http://www.enterprisedb.com


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