Hi,

Postgres optimizer automatically tries to convert an IN clause to Hash Join
(something similar to EXISTS equivalent of that query).

Does a similar translation happen for NOT IN as well? Given that the column
used is NOT NUL.

Select * from emp where deptid not in (select deptid from dept where
deptLocation='New York');

Will this above statement be automatically converted to a plan which would
match below statement?

Select * from emp where not exists (select 1 from dept where
deptLocation='New York' and dept.deptid=emp.deptid);

 Regards
Sameer

PS: Sent from my Mobile device. Pls ignore typo n abb

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