Re: Fwd: Slow query from ~7M rows, joined to two tables of ~100 rows each

From: Karl Czajkowski <karlcz(at)isi(dot)edu>
To: Chris Wilson <chris+postgresql(at)qwirx(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org, george(dot)saklatvala(at)cantabcapital(dot)com
Subject: Re: Fwd: Slow query from ~7M rows, joined to two tables of ~100 rows each
Date: 2017-06-26 20:32:21
Message-ID: 20170626203221.GA10516@moraine.isi.edu
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

On Jun 26, Chris Wilson modulated:

> I created the index starting with date and it did make a big
> difference: down to 10.3 seconds using a bitmap index scan and bitmap
> heap scan (and then two hash joins as before).
>

By the way, what kind of machine are you using? CPU, RAM, backing
storage?

I tried running your original test code and the query completed in
about 8 seconds, and adding the index changes and analyze statement
brought it down to around 2.3 seconds on my workstation with Postgres
9.5.7. On an unrelated development VM with Postgres 9.6.3, the final
form took around 4 seconds.

Karl

In response to

Browse pgsql-performance by date

  From Date Subject
Next Message Jeff Janes 2017-06-26 21:22:51 Re: Fwd: Slow query from ~7M rows, joined to two tables of ~100 rows each
Previous Message Karl Czajkowski 2017-06-26 17:01:20 Re: Fwd: Slow query from ~7M rows, joined to two tables of ~100 rows each