Re: select query does not pick up the right index

Oups wrong copy and paste. I did run your query with equal instead of in but it resulted in the same plan
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From: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
Sent: 09 January 2019 17:41:24
To: Abadie Lana
Cc: Justin Pryzby; pgsql-performance(at)lists(dot)postgresql(dot)org
Subject: Re: select query does not pick up the right index

On Thu, 10 Jan 2019 at 01:55, Abadie Lana <Lana(dot)Abadie(at)iter(dot)org> wrote:
> The other query suggested by D.Rowley has the same issue : still swap activity is higher.
> explain analyze select 'BUIL-B36-VA-RT-RT1:CL0001-2-ABW', c.smpl_time,c.nanosecs,c.float_val,c.num_val,c.str_val,c.datatype,c.array_val from sample c where c.channel_id in (select channel_id from channel where name ='BUIL-B36-VA-RT-RT1:CL0001-2-ABW') order by c.smpl_time desc limit 5;

This is not the query I suggested. I mentioned if channel.name had a
unique index, you'd be able to do WHERE c.channel_id = (select
channel_id from channel where name = '...'). That's pretty different
to what you have above.

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David Rowley http://www.2ndQuadrant.com/
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