More than one Thread accessing the same records in the database

Question

Hi, I have more than one thread accessing a synchronized method called getMinPrimaryKey() which gets the lowest of the primary key frm the table based on the a flag which is set to true. once it is retrieved the same method also sets the flag as false so it is not retrieved the second time. so next time a different thread calls this method it should retrieve the next available lowest primarmy key.
but even when i have the method as synchronized different threads keep returning the same primary key instead of getting the next sequence. can some one let me know where I might go wrong and what could be the solution. is it because when once i retrieve the record and set the flag as false, i also need to commit it?, which could be the reason the select query still picks up the same primary key. please help me out on this.
thanks,
Harish

Answer 1

Correction. If different threads always return the same key then your table isn't getting up dated. If different threads sometimes return the same key, then either the database is committing lazily, or else the threads are calling getMinPrimaryKey on different objects and so are not executing atomically with respect to each other.