Mysql數(shù)據(jù)庫(kù)中datetime、bigint、timestamp來(lái)表示時(shí)間選擇,誰(shuí)來(lái)存儲(chǔ)時(shí)間效率最高
數(shù)據(jù)庫(kù)中可以用datetime、bigint、timestamp來(lái)表示時(shí)間,那么選擇什么類型來(lái)存儲(chǔ)時(shí)間比較合適呢?
# 后數(shù)據(jù)準(zhǔn)備
通過(guò)程序往數(shù)據(jù)庫(kù)插入50w數(shù)據(jù)
數(shù)據(jù)表:
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為同一時(shí)間的不同存儲(chǔ)格式
實(shí)體類users
/** * @author hetiantian * @date 2018/10/21 * */ @Builder @Data public class Users { /** * 自增唯一id * */ private Long id; /** * date類型的時(shí)間 * */ private Date timeDate; /** * timestamp類型的時(shí)間 * */ private Timestamp timeTimestamp; /** * long類型的時(shí)間 * */ private long timeLong; }
dao層接口
/** * @author hetiantian * @date 2018/10/21 * */ @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); }
測(cè)試類往數(shù)據(jù)庫(kù)插入數(shù)據(jù)
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()); } } }
生成數(shù)據(jù)代碼方至github:https://github.com/TiantianUpup/sql-test/ 如果不想用代碼生成,而是想通過(guò)sql文件倒入數(shù)據(jù),文末附sql文件網(wǎng)盤(pán)地址。
# sql查詢速率測(cè)試
通過(guò)datetime類型查詢:
select count(*) from users where time_date >="2018-10-21 23:32:44" and time_date <="2018-10-21 23:41:22"
耗時(shí):0.171
通過(guò)timestamp類型查詢
select count(*) from users where time_timestamp >= "2018-10-21 23:32:44" and time_timestamp <="2018-10-21 23:41:22"
耗時(shí):0.351
通過(guò)bigint類型查詢
select count(*) from users where time_long >=1540135964091 and time_long <=1540136482372
耗時(shí):0.130s
結(jié)論 在InnoDB存儲(chǔ)引擎下,通過(guò)時(shí)間范圍查找,性能bigint > datetime > timestamp
# sql分組速率測(cè)試
使用bigint 進(jìn)行分組會(huì)每條數(shù)據(jù)進(jìn)行一個(gè)分組,如果將bigint做一個(gè)轉(zhuǎn)化在去分組就沒(méi)有比較的意義了,轉(zhuǎn)化也是需要時(shí)間的
通過(guò)datetime類型分組:
select time_date, count(*) from users group by time_date
耗時(shí):0.176s
通過(guò)timestamp類型分組:
select time_timestamp, count(*) from users group by time_timestamp
耗時(shí):0.173s
結(jié)論 在InnoDB存儲(chǔ)引擎下,通過(guò)時(shí)間分組,性能timestamp > datetime,但是相差不大
# sql排序速率測(cè)試
通過(guò)datetime類型排序:
select * from users order by time_date
耗時(shí):1.038s
通過(guò)timestamp類型排序
select * from users order by time_timestamp
耗時(shí):0.933s
通過(guò)bigint類型排序
select * from users order by time_long
耗時(shí):0.775s
結(jié)論:在InnoDB存儲(chǔ)引擎下,通過(guò)時(shí)間排序,性能bigint > timestamp > datetime
# 小結(jié)
如果需要對(duì)時(shí)間字段進(jìn)行操作(如通過(guò)時(shí)間范圍查找或者排序等),推薦使用bigint,如果時(shí)間字段不需要進(jìn)行任何操作,推薦使用timestamp,使用4個(gè)字節(jié)保存比較節(jié)省空間,但是只能記錄到2038年記錄的時(shí)間有限。
文中sql文件網(wǎng)盤(pán)地址: 鏈接: https://pan.baidu.com/s/1cCRCxtTlPriXMERGsbnb_A 提取碼: hbq2
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