如何在大数据的MySQL上通过计算优化更新查询

Question

i want to update data on mysql table, this table have 2.258.164 row there is the query

select ch_0  
from bmkg.tb_datastore_2017 
WHERE id_station='150001' 
AND date_time<'2017-02-06 17:30:00' 
and DATE_FORMAT(`date_time`,'%Y-%m-%d') = '2017-02-06' 
order by date_time Desc limit 1

this query need 55-60 second, its to slowly, Please help me to optimize this.. Thank you, Warmest regards,

Answer 1

You can use BETWEEN to prevent a FULL TABLE SCAN

SELECT  ch_0  
FROM bmkg.tb_datastore_2017 
WHERE id_station='150001' 
AND `date_time` BETWEEN '2017-02-06 00:00:00' AND  '2017-02-06 17:30:00'
ORDER BY date_time DESC
LIMIT 1;

please post also the EXPLAIN of my query to see if there are any INDEX

Answer 2

SELECT  ch_0  
FROM bmkg.tb_datastore_2017 
WHERE id_station='150001' 
AND `date_time` BETWEEN '2017-02-06 00:00:00' AND  '2017-02-06 17:30:00'
ORDER BY date_time DESC
LIMIT 1;

Please try this.And let me know how much time it took to execute with same data. Hope this will helps you.

Answer 3

You can also use like this :-

select ch_0  
from bmkg.tb_datastore_2017
WHERE id_station='150001'
AND date_time<'2017-02-06 17:30:00' and DATE(`date_time`) = '2017-02-06'
order by date_time Desc limit 1;

I too was stuck with such issue and using Date() function solved by problem or else you can share EXPLAIN plan for your query so that we can analyse more.

Thanks,