When conducting performance tests of our application, I saw quite a few exclusive locks in SELECTs with WITH clause. So I created a big table and executed a query which takes time. with x as (select * from emp where first_name like 'Sco%') select * from x; I got 2 locks - one accesshare lock against the table and one ExclusiveLock with out any database/relation. 2417 postgres 10/95 10/95 ExclusiveLock Yes 2013-11-23 17:38:58+05:30
My guess is that the Exclusive lock is against some in-memory structure (the temp table created by the WITH clause) and hence is not an issue. Is that correct?
