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1293897600
然后
select COUNT(*) from 20130107date where c_date_long BETWEEN 1293811200 and 1293897600;
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.