mysqltimestamp和long存储时间效率比较_MySQL

<code class="hljs sql">show create table 20130107date;

CREATE TABLE `20130107date` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `c_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `c_date_long` int(20) NOT NULL,
  `idx_date` timestamp NOT NULL DEFAULT &#39;0000-00-00 00:00:00&#39;,
  `idx_date_long` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `20130107date_idx_date` (`idx_date`),
  KEY `20130107date_idx_long` (`idx_date_long`)
) ENGINE=InnoDB
</code>

里面有90w数据,都是随机的时间.<br> 先看没有索引的全表扫描

1 :

<code class="hljs sql"><code class="hljs sql">select COUNT(*) from 20130107date
where c_date BETWEEN DATE(&#39;20110101&#39;) and DATE(&#39;20110102&#39;)</code></code>

<code class="hljs sql">这个需要1.54s

<code class="hljs sql">2:

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql">select COUNT(*) from 20130107date
where c_date_long BETWEEN UNIX_TIMESTAMP(&#39;20110101&#39;) and UNIX_TIMESTAMP(&#39;20110102&#39;)</code></code></code>

<code class="hljs sql"><code class="hljs sql">这个是2.3s

<code class="hljs sql"><code class="hljs sql">但是可以这样搞<br> 3 :

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql">select UNIX_TIMESTAMP(&#39;20110101&#39;),UNIX_TIMESTAMP(&#39;20110102&#39;);</code></code></code></code>

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql">得到结果1293811200和1293897600

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql">然后

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql">select COUNT(*) from 20130107date
where c_date_long BETWEEN 1293811200 and 1293897600；</code></code></code></code></code>

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql">发现变成了0.61s<br> 1和2的差距还可以说是比较int和比较timestamp的差距,那么2和3的差距呢?难道多出来的时间是每一条记录都要evaluate UNIX_TIMESTAMP(‘20110102’)?

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql">然后用索引

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql">select COUNT(*) from 20130107date
where idx_date_long BETWEEN UNIX_TIMESTAMP(&#39;20110101&#39;) and UNIX_TIMESTAMP(&#39;20110102&#39;);

select COUNT(*) from 20130107date
where idx_date BETWEEN &#39;20110101&#39; and &#39;20110102&#39;</code></code></code></code></code></code>

<code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql"><code class="hljs sql">毫无悬念,两个基本都是瞬时的.