Select distinct … inner join vs. select … where id in (…)

Question

I\'m trying to create a subset of a table (as a materialized view), defined as those records which have a matching record in another materialized view.

For example,

Answer 1

Try this

select * from Users u
where exists 
   ( select user_id 
     from Log_mview l
     where l.user_id = u.user_id )
/

If the sub-query returns a large number of rows WHERE EXISTS can be substantially faster than WHERE ... IN.