Need help/tools to compare SQL queries - sql

Question

I have this comments table with over 4 million rows:
CREATE TABLE `comments`
(
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`gid` int(11) unsigned NOT NULL DEFAULT '0',
`userid` int(6) unsigned DEFAULT NULL,
`date` int(11) unsigned DEFAULT NULL,
`comment` text NOT NULL,
`status` enum('on','alert') NOT NULL DEFAULT 'on',
PRIMARY KEY (`id`),
KEY `gid_2` (`gid`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
now I'm thinking about extracting the text-field to decrease the 400 MB and increase performance. Like this:
CREATE TABLE commentstext
(
id int(11) unsigned NOT NULL AUTO_INCREMENT,
`comment` text NOT NULL,
PRIMARY KEY (id)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
but I'm not sure if this will perform better this way. I need to test this cases by using different queries (also). My results so far differ a lot. Between 0.001* - 3.321 sec. I'm not able to check this by querying in phpmyadmin.
Is there a better and easy way or tool to compare queries performance?

Answer 1

That's what I was looking for:
SELECT BENCHMARK(1000000000, (
SELECT
comments.comment
FROM
comments
WHERE
`gid`=303410
LIMIT 1
));
(result 34.1612 sec.)
(result 32.2737 sec.)
SELECT BENCHMARK(1000000000, (
SELECT
commentstext.comment
FROM
commentsindex,
commentstext
WHERE
`gid`=303410
AND commentsindex.`id` = commentstext.`id`
LIMIT 1
));
(result 34.1237 sec.)
(result 34.2914 sec.)
SELECT BENCHMARK(1000000000, (
SELECT
commentstext.comment
FROM
commentsindex
INNER JOIN
commentstext
ON commentstext.`id` = commentsindex.`id`
WHERE
`gid`=303410
LIMIT 1
));
(result 32.8471 sec.)
(result 34.7079 sec.)
... but now I'm really wondering that it doesn't matter, which table design is in use. confused