Commit when exceptionn occurs?

Question

public static void main(String args[])
method1();//transaction1
method2()// transaction2
// catching exception here
say we have a main method main . In that main method we call method1 which creates a customer using connection con1. Then we call method2() which creates
the account for customer using same connection con1.I have two questions on above
1)Assume some exception occurs during method2 and we catch the exception and do con1.commit(); Will the transaction1 still be commited ?
2) Assume no exception occurs. But When we do con1.commit jvm crashes and transaction is not committed yet, Now when we restart the application
will that transaction be committed?

Answer 1

JavaFunda wrote:
public static void main(String args[])
method1();//transaction1
method2()// transaction2
// catching exception here
say we have a main method main . In that main method we call method1 which creates a customer using connection con1. Then we call method2() which creates
the account for customer using same connection con1.I have two questions on above
1)Assume some exception occurs during method2 and we catch the exception and do con1.commit(); Will the transaction1 still be commited ?Yes, t1 will be committed. Additionally, any changes that were part of t2 that occurred before the exception will be committed, because in reality, if you don't commit until {t1; part of t2; catch}, t1 and t2 are the same--there's only one transaction.
Committing in a catch block is a bad idea, because you don't know how much was done before the error occurred.
It defeats the purpose of a transaction, which is that either all happens, or none happens.
2) Assume no exception occurs. But When we do con1.commit jvm crashes and transaction is not committed yet, Now when we restart the application
will that transaction be committed?Impossible to say, but then, you don't actually care. and it shouldn't matter.
Since you're talking about the JVM crashing at an inopportune moment, there's always the chance of the commit either succeeding or failing, and then the JVM crashesbefore you can find out, so no matter what, you have to assume that when restarting after a crash, you'll have to figure out which transactions failed and which succeeded, if that matters to you.
Edited by: jverd on Jul 21, 2011 9:54 AM