mysql关于order by效率很慢的问题
select
ts.uploadDate,
tv.carNumber as CarNumber,
tv.id as VinId,tu.nick as Nick,
tu.userName as UserName,
tu.id as UserId,
ts.id as Id
from t_travel_data_summarize ts
left outer join t_vin tv on ts.vinId = tv.id
left join t_user tu on ts.userId = tu.id
where Length(tv.carNumber) > 7 and tv.carNumber !='无车牌' and tv.carNumber != '测试车'
group by ts.vinId order by ts.id desc limit 6
rows
1 SIMPLE ts index index_vinid PRIMARY 4 6 Using temporary
1 SIMPLE tv eq_ref PRIMARY PRIMARY 4 qcwp_auto_data.ts.VinId 1 Using where
1 SIMPLE tu eq_ref PRIMARY PRIMARY 4 qcwp_auto_data.ts.UserId 1
查询时间接近1分钟,把order by去掉瞬间出来,有大神可以解答下吗