I have a question about MySQL performance
Query1:
select departments.*, booth_feature.some_feature
from departments
left join booth on booth.dept_id = departments.dept_id
left join booth_feature on booth.booth_id=booth_feature.booth_id
Query2:
select departments.*, booth_feature.some_feature
from departments
left join (booth, booth_feature) on ( booth.dept_id = departments.dept_id and booth.booth_id=booth_feature.booth_id)
Assuming: a department may have several cabins
1 stand => 1 stand function
both department and stand tables are large tables.
Using the clarification, the first query seems better (it checks the stand before booth_feature), although the left join is usually more expensive than the inner join. It is right?
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