Oups wrong copy and paste. I did run your query with equal instead of in but it resulted in the same plan ________________________________ From: David Rowley <david.row...@2ndquadrant.com> Sent: 09 January 2019 17:41:24 To: Abadie Lana Cc: Justin Pryzby; pgsql-performance@lists.postgresql.org Subject: Re: select query does not pick up the right index
On Thu, 10 Jan 2019 at 01:55, Abadie Lana <lana.aba...@iter.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. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
