Hello!
We have a huge POSTGRES 9.4 database in the production environment (several tables have more than 100.000.00 registers). Last two months we have had problems with CPU utilization. Debugging the locks (on pg_locks) we notice that sometimes simple UPDATE (by primary key) operation takes out ACCESS_EXCLUSIVE_LOCK mode over these huge tables so POSTGRES DB collapses and it generates excessive CPU consumption. My question is, How is it possible that UPDATE operation takes out ACCESS_EXCLUSIVE_LOCK mode?
More information, this system never manifests this behavior before and we don't make software changes on last 2 years
