mysql數(shù)據(jù)庫時(shí)間類型datetime、bigint、timestamp的查詢效率比較
數(shù)據(jù)庫中可以用datetime、bigint、timestamp來表示時(shí)間，那么選擇什么類型來存儲(chǔ)時(shí)間比較合適呢？
前期數(shù)據(jù)準(zhǔn)備
通過程序往數(shù)據(jù)庫插入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：github.com/TiantianUpu…如果不想用代碼生成，而是想通過sql文件倒入數(shù)據(jù)，附sql文件網(wǎng)盤地址：pan.baidu.com/s/1Qp9x6z8C…
sql查詢速率測(cè)試
通過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)化在去分組就沒有比較的意義了，轉(zhuǎn)化也是需要時(shí)間的
通過datetime類型分組：
select?time_date, count(*) from?users?group?by?time_date耗時(shí)：0.176s
通過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datetime類型排序：
select?* from?users?order?by?time_date耗時(shí)：1.038s
通過timestamp類型排序
select?* from?users?order?by?time_timestamp耗時(shí)：0.933s
通過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
鏈接：juejin.im/post/6844903701094596615