Hi!
I have a problem with ACCESS EXCLUSIVE lock when I drop a reference in
transaction. I have 2 tables:
create table a(id SERIAL primary key);
create table b(id SERIAL primary key references a(id));
After that I have 2 processes: P1, P2
In P1:
begin;
ALTER TABLE b DROP CONSTRAINT b_id_fkey;
In P2:
SELECT * FROM a;
And I'm waiting for the result, but I don't get until P1 finishes.
I know the DROP CONSTRAINT put an ACCESS EXCLUSIVE table LOCK into the
TABLE a, and the SELECT is stopped by this LOCK in P2.
Note: I cannot commit the P1 earlier, because it's a very long
transaction (more hours, data conversion transaction)
My question: Why need this strict locking?
In my opinion there isn't exclusion between the DROP CONSTRAINT and the
SELECT.
Thanks for your suggestions!
Regards,
Antal Attila
