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Mysql in statement performance related with its position?
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 forder by 1d_retain_rate desclimit 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 forder by 1d_retain_rate desclimit 0,50;
Mysql in statement performance related with its position?
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