RE: select query does not pick up the right index

Lana ABADIE
Database Engineer
CODAC Section

ITER Organization, Building 72/4108, SCOD, Control System Division
Route de Vinon-sur-Verdon - CS 90 046 - 13067 St Paul Lez Durance Cedex - France
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-----Original Message-----
From: Justin Pryzby <pryzby(at)telsasoft(dot)com>
Sent: 02 January 2019 17:45
To: Abadie Lana <Lana(dot)Abadie(at)iter(dot)org>
Cc: pgsql-performance(at)lists(dot)postgresql(dot)org
Subject: Re: select query does not pick up the right index

On Wed, Jan 02, 2019 at 04:28:41PM +0000, Abadie Lana wrote:
> css_archive_3_0_0=# explain analyze select t.name, c.smpl_time,c.nanosecs,c.float_val,c.num_ val,c.str_val,c.datatype,c.array_val from sample c, channel t where t.channel_id=c.channel_i d and t.name='BUIL-B36-VA-RT-RT1:CL0001-2-ABW' order by c.smpl_time desc limit 5;
> QUERY PLAN
>
> --------------------------------------------------------------------------------------------
> --------------------------------------------------------------------------------------------
> -------------
> Gather (cost=1004.71..125606.08 rows=5 width=150) (actual time=38737.443..1220277.244 rows
> =3 loops=1)
> Workers Planned: 1
> Workers Launched: 1
> Single Copy: true

Do you have force_parallel_mode set ?

http://rhaas.blogspot.com/2018/06/using-forceparallelmode-correctly.html

--
Justin Pryzby
System Administrator
Telsasoft
+1-952-707-8581

Hi Justin
Indeed force_parallel_mode was set to on. Even after disabling it, same issue...
cheers