From: Dave Dutcher <dave@tridecap.com>
To: 'Clemens Eisserer' <linuxhippy@gmail.com>
To: pgsql-performance@postgresql.org
Subject: Re: Question about explain-command...
Date: Wed, 10 May 2006 09:47:07 -0500
Message-ID: <01a901c67440$9cf097e0$8300a8c0@tridecap.com> (raw)
In-Reply-To: <194f62550605100449p2d200fc3pfe501da895cfcc00@mail.gmail.com>
> -----Original Message-----
> From: pgsql-performance-owner@postgresql.org
> [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of
> Clemens Eisserer
> Sent: Wednesday, May 10, 2006 6:50 AM
> To: pgsql-performance@postgresql.org
> Subject: [PERFORM] Question about explain-command...
>
> What does the hash-lines mean, does that mean my query does not use
> the indices at all?
> Why are some table-names and some column-names surrounded by ' " '?
> Are they threated as text-columns?
> I have to admit that the tables are just filled with test-data so the
> analyzer may take just a very simple way since almost no data is in...
>
For small tables, it is faster to do a sequential scan than an index
scan. You probably don't have enough test data to make the planner
choose an index scan.
I don't think the quotes really mean anything. They are just used as
delimiters.
The hash lines mean your tables are being joined by hash joins. You
should read this page for more info:
http://www.postgresql.org/docs/8.1/interactive/performance-tips.html
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: dave@tridecap.com, linuxhippy@gmail.com
Subject: Re: Question about explain-command...
In-Reply-To: <01a901c67440$9cf097e0$8300a8c0@tridecap.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox