Neil Harkins wrote on 29.01.2014 23:37:
> I totally understand DDL taking exclusive locks, the problem here seems to be that the *SELECTs*
>are taking out exclusive locks, locking out the ALTER, which feels like a bug.
The SELECT is not holding an exclusive lock, it's holing a *shared* lock, but the ALTER is _requesting_ an exclusive
lockand that can only be granted until all shared (or otherwise incompatible) locks are released.