时间戳
如果需要对
时间字段进行操作(如通过时间范围查找或者排序等)，推荐使用bigint，如果时间字段不需要进行任何操作，推荐使用timestamp，使用4个字节保存比较节省空间，但是只能记录到2038年记录的时间有限
CREATE TABLE `users` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`time_date` datetime NOT NULL,
`time_timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`time_long` bigint(20) NOT NULL,
PRIMARY KEY (`id`),
KEY `time_long` (`time_long`),
KEY `time_timestamp` (`time_timestamp`),
KEY `time_date` (`time_date`)
) ENGINE=InnoDB AUTO_INCREMENT=500003 DEFAULT CHARSET=latin1
@Builder
@Data
public class Users {
/**
* 自增唯一id
* */
private Long id;
/**
* date类型的时间
* */
private Date timeDate;
/**
* timestamp类型的时间
* */
private Timestamp timeTimestamp;
/**
* long类型的时间
* */
private long timeLong;
}
@Mapper
public interface UsersMapper {
@Insert("insert into users(time_date, time_timestamp, time_long) value(#{timeDate}, #{timeTimestamp}, #{timeLong})")
@Options(useGeneratedKeys = true,keyProperty = "id",keyColumn = "id")
int saveUsers(Users users);
}
public class UsersMapperTest extends BaseTest {
@Resource
private UsersMapper usersMapper;
@Test
public void test() {
for (int i = 0; i < 500000; i++) {
long time = System.currentTimeMillis();
usersMapper.saveUsers(Users.builder().timeDate(new Date(time)).timeLong(time).timeTimestamp(new Timestamp(time)).build());
}
}
}
- sql查询速率测试
#通过datetime类型查询： 耗时：0.171
select count(*) from users where time_date >="2018-10-21 23:32:44" and time_date <="2018-10-21 23:41:22"
#通过timestamp类型查询: 耗时：0.351
select count(*) from users where time_timestamp >= "2018-10-21 23:32:44" and time_timestamp <="2018-10-21 23:41:22"
#通过bigint类型查询: 耗时：0.130s
select count(*) from users where time_long >=1540135964091 and time_long <=1540136482372
#通过datetime类型分组： 耗时：0.176s
select time_date, count(*) from users group by time_date
#通过timestamp类型分组： 耗时：0.173s
select time_timestamp, count(*) from users group by time_timestamp
- 结论 在InnoDB存储引擎下，通过时间分组，性能timestamp > datetime，但是相差不大
#通过datetime类型排序： 耗时：1.038s
select * from users order by time_date
#通过timestamp类型排序： 耗时：0.933s
select * from users order by time_timestamp
#通过bigint类型排序： 耗时：0.775s
select * from users order by time_long
- 结论 在InnoDB存储引擎下，通过时间排序，性能bigint > timestamp > datetime