标签:des style blog io color os sp for strong
select * from ( select event_date, ‘2014-12-06‘ as active_date, channel_id, new_user_count as new_user_count, 1d_retain/new_user_count as 1d_retain_rate from web_channel_retain where app_id=-1 and event_date=‘2014-12-05‘ and new_user_count>= 500 and channel_id in (select distinct channel_id from formated_channel_category where type_id=507 ) )as f order by 1d_retain_rate desc limit 0,50;
The above sql runs less than 2 seconds, while below sql runs a long time(I killed it before it completed). The only difference is the position of in statement.
select * from ( select event_date, ‘2014-12-06‘ as active_date, channel_id, new_user_count as new_user_count, 1d_retain/new_user_count as 1d_retain_rate from web_channel_retain where channel_id in (select distinct channel_id from formated_channel_category where type_id=507 ) and app_id=-1 and event_date=‘2014-12-05‘ and new_user_count>= 500 )as f order by 1d_retain_rate desc limit 0,50;
Mysql in statement performance related with its position?
标签:des style blog io color os sp for strong
原文地址:http://www.cnblogs.com/linghuaichong/p/4149835.html