Hello. I had a strange issue with postgresql 9.3 server. Load on server rapidly increased, queries which took about 4ms were executed for 100ms and creation a foreign key on empty table blocked all queries to server. After server restart everithing became fine again, the same foreign key was created less then in a second, and queries worked fast again. What may be the reason?
I understand that this information is not enough to give some reasonable answer but still will be grateful for any advise.