From: Tom Lane <tgl@sss.pgh.pa.us>
To: Suya Huang <shuang@connexity.com>
Cc: Claudio Freire <klaussfreire@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: what's the slowest part in the SQL
Date: Tue, 09 Aug 2016 20:45:23 -0400
Message-ID: <12338.1470789923@sss.pgh.pa.us> (raw)
In-Reply-To: <F21B81F4-E136-4F46-AD90-310BF8C257A1@connexity.com>
References: <1D0FF65A-EAB9-453C-9B95-684E05B494B7@connexity.com>
<CAGTBQpYz8mFz9kie740ayGysfST35s3zAvpL-wrM8UNtCT22mA@mail.gmail.com>
<001EBA46-372C-4325-9AC5-168E19949C8A@connexity.com>
<CAGTBQpZfyj9252RYGY7+EL540mXxd4dRTRGZtQWYFJm63Byj2Q@mail.gmail.com>
<F21B81F4-E136-4F46-AD90-310BF8C257A1@connexity.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>
Suya Huang <shuang@connexity.com> writes:
> -> Index Scan using idx_order_1_us on order o (cost=0.56..8.58 rows=1 width=30) (actual time=5.814..5.814 rows=0 loops=526)
4 or so ms per row fetched is well within expectation for random access to
spinning-rust media. For example, a 15K RPM drive spins at 4 ms per
revolution, so rotational delay alone would probably explain this number,
never mind needing to do any seeks. So I see nothing even slightly
unexpected here, assuming that the "order" table is large enough that none
of what you need is in RAM already. If you need more performance, look
into SSDs.
(If you have storage kit for which you'd expect better performance than
this, you should start by explaining what it is.)
regards, tom lane
--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
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: tgl@sss.pgh.pa.us, shuang@connexity.com, klaussfreire@gmail.com
Subject: Re: what's the slowest part in the SQL
In-Reply-To: <12338.1470789923@sss.pgh.pa.us>
* 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