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Re: Why should such a simple query over indexed columns be so slow?

From: Claudio Freire <klaussfreire(at)gmail(dot)com>
To: Alessandro Gagliardi <alessandro(at)path(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Why should such a simple query over indexed columns be so slow?
Date: 2012-01-30 20:50:21
Message-ID: CAGTBQpYkABcva8=PzXyzRFqxMKjsXhXfZT-k2tsLh61h-aLsAw@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Mon, Jan 30, 2012 at 5:35 PM, Alessandro Gagliardi
<alessandro(at)path(dot)com> wrote:
> To answer your (non-)question about Heroku, it's a cloud service, so I don't
> host PostgreSQL myself. I'm not sure how much I can mess with things like
> GUC since I don't even have access to the "postgres" database on the server.
> I am a long time SQL user but new to Postgres so I welcome suggestions on
> where to start with that sort of thing. SettingĀ enable_seqscan=false made a
> huge difference, so I think I'll start there.

It's not a good idea to abuse of the enable_stuff settings, they're
for debugging, not for general use. In particular, disable sequential
scans everywhere can have a disastrous effect on performance.

It sounds as if PG had a misconfigured effective_cache_size. What does
"show effective_cache_size" tell you?

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Subject: Re: Why should such a simple query over indexed columns be so slow?
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