Mladen Gogala <gogala.mladen@xxxxxxxxx> writes: > I tried the following: > _*1st Session:*_ > mgogala=# begin transaction; > BEGIN > mgogala=*# update emp set sal=sal*1 where empno=7934; > UPDATE 1 > mgogala=*# > _*2nd Session:*_ > mgogala=# begin transaction; > BEGIN > mgogala=*# select pg_try_advisory_lock(0) from (select ename from emp > where empno=7934 for update) as tbl; > To my infinite surprise, "pg_advisory_lock" is waiting. I doubt it. I think the FOR UPDATE in the sub-select is blocked because the other session has an uncommitted update on the row it wants to lock. This command won't reach the pg_try_advisory_lock call until that row lock comes free. regards, tom lane
