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 '0000-00-00 00:00:00',
`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
里面有90w数据,都是随机的时间.
先看没有索引的全表扫描
1 :
select COUNT(*) from 20130107date
where c_date BETWEEN DATE('20110101') and DATE('20110102')
这个需要1.54s
2:
select COUNT(*) from 20130107date
where c_date_long BETWEEN UNIX_TIMESTAMP('20110101') and UNIX_TIMESTAMP('20110102')
这个是2.3s
但是可以这样搞
3 :
select UNIX_TIMESTAMP('20110101'),UNIX_TIMESTAMP('20110102');
得到结果1293811200和12937600
然后
select COUNT(*) from 20130107date
where c_date_long BETWEEN 1293811200 and 12937600；
发现变成了0.61s
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’)?
然后用索引
select COUNT(*) from 20130107date
where idx_date_long BETWEEN UNIX_TIMESTAMP('20110101') and UNIX_TIMESTAMP('20110102');
select COUNT(*) from 20130107date
where idx_date BETWEEN '20110101' and '20110102'
毫无悬念,两个基本都是瞬时的.