MySQL数据库时间类型datetime、bigint、timestamp的查询效率比较
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数据库中可以用datetime、bigint、timestamp来表示时间，那么选择什么类型来存储时间比较合适呢？文章源自JAVA秀-https://www.javaxiu.com/37963.html
前期数据准备
通过程序往数据库插入50w数据文章源自JAVA秀-https://www.javaxiu.com/37963.html
数据表：文章源自JAVA秀-https://www.javaxiu.com/37963.html
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其中time_long、time_timestamp、time_date为同一时间的不同存储格式文章源自JAVA秀-https://www.javaxiu.com/37963.html
实体类users文章源自JAVA秀-https://www.javaxiu.com/37963.html
/** * @author hetiantian * @date 2018/10/21 * */@Builder@Datapublic 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;}dao层接口文章源自JAVA秀-https://www.javaxiu.com/37963.html
/** * @author hetiantian * @date 2018/10/21 * */@Mapperpublic 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);}测试类往数据库插入数据文章源自JAVA秀-https://www.javaxiu.com/37963.html
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：文章源自JAVA秀-https://www.javaxiu.com/37963.html
select count(*) from users where time_date >="2018-10-21 23:32:44" and time_date <="2018-10-21 23:41:22"耗时：0.171文章源自JAVA秀-https://www.javaxiu.com/37963.html
通过timestamp类型查询文章源自JAVA秀-https://www.javaxiu.com/37963.html
select count(*) from users where time_timestamp >= "2018-10-21 23:32:44" and time_timestamp <="2018-10-21 23:41:22"耗时：0.351文章源自JAVA秀-https://www.javaxiu.com/37963.html
通过bigint类型查询文章源自JAVA秀-https://www.javaxiu.com/37963.html
select count(*) from users where time_long >=1540135964091 and time_long <=1540136482372 耗时：0.130s文章源自JAVA秀-https://www.javaxiu.com/37963.html
结论 在InnoDB存储引擎下，通过时间范围查找，性能bigint > datetime > timestamp文章源自JAVA秀-https://www.javaxiu.com/37963.html
sql分组速率测试
使用bigint 进行分组会每条数据进行一个分组，如果将bigint做一个转化在去分组就没有比较的意义了，转化也是需要时间的文章源自JAVA秀-https://www.javaxiu.com/37963.html
通过datetime类型分组：文章源自JAVA秀-https://www.javaxiu.com/37963.html
select time_date, count(*) from users group by time_date耗时：0.176s文章源自JAVA秀-https://www.javaxiu.com/37963.html
通过timestamp类型分组：文章源自JAVA秀-https://www.javaxiu.com/37963.html
select time_timestamp, count(*) from users group by time_timestamp耗时：0.173s文章源自JAVA秀-https://www.javaxiu.com/37963.html
结论 在InnoDB存储引擎下，通过时间分组，性能timestamp > datetime，但是相差不大文章源自JAVA秀-https://www.javaxiu.com/37963.html
sql排序速率测试
通过datetime类型排序：文章源自JAVA秀-https://www.javaxiu.com/37963.html
select * from users order by time_date耗时：1.038s文章源自JAVA秀-https://www.javaxiu.com/37963.html
通过timestamp类型排序文章源自JAVA秀-https://www.javaxiu.com/37963.html
select * from users order by time_timestamp耗时：0.933s文章源自JAVA秀-https://www.javaxiu.com/37963.html
通过bigint类型排序文章源自JAVA秀-https://www.javaxiu.com/37963.html
select * from users order by time_long耗时：0.775s文章源自JAVA秀-https://www.javaxiu.com/37963.html
结论 在InnoDB存储引擎下，通过时间排序，性能bigint > timestamp > datetime文章源自JAVA秀-https://www.javaxiu.com/37963.html
小结
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年记录的时间有限文章源自JAVA秀-https://www.javaxiu.com/37963.html
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