Can someone point me to documentation on (or confirm) this detail on Postgres locking?
- Transaction X starts and acquires a lock on a table T
- Transaction Y starts and attempts to acquire a conflicting lock on T - it is now blocked
- Transaction Z starts and also attempts to acquire a conflicting lock on T - it is now blocked
Is txn Y guaranteed to be the first txn to proceed once X finishes? Is there some "lock queue order" that is respected? Is there any chance Z can proceed before Y, say if it acquires a less aggressive lock?
Put differently: when txn Y starts, it has to wait. Is this wait time at most the length of the longest txn older than Y?
Thanks,
Josh