Date: Sat, 9 Feb 2019 11:16:33 -0600
From: Justin Pryzby <pryzby@telsasoft.com>
To: Evandro Abreu <evandro.abreu@gmail.com>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: slow to run query 5000 times
Message-ID: <20190209171633.GO31721@telsasoft.com>
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Hi,

Please don't send images to the list, you can send a link to one of the image
host websites if you need to describe something graphical.

But here, you could just send the queries and \d for the tables.

On Sat, Feb 09, 2019 at 01:45:50PM -0300, Evandro Abreu wrote:
> I have a report that takes about 20 minutes to generate. It is generated
> from 3 tables: according to image.
> The report input parameter is a date range. So to generate it I select all
> records in Table A and run them
> in loop-for. For each record in Table A I make a query Table B join with
> Table C where I filter the records through the date field and make the sum
> of the value field.

So you're running query 5000 times ?

Do you really need a for loop ?  Could you just join the 3 tables together and GROUP BY a.id ?

Please send "explain analyze" for the queries, or a link to the output on
depesz site.
https://wiki.postgresql.org/wiki/Slow_Query_Questions#Information_You_Need_To_Include

Also, are they all taking about the same amount of time ?

Justin