José José Ventura-3 wrote > By default, connections start in Auto-Commit mode, which means every > statement is executed as a single transaction. > http://docs.oracle.com/javase/tutorial/jdbc/basics/transactions.html#disable_auto_commit > > To group several statements in a transaction, you first set autoCommit to > false (just like your example); then, execute all the statements you want; > and then execute *conn.commit()* (or *conn.rollback()* if you detect an > error). Since you said everything is working, I assume there is a call to > conn.commit() somewhere in your code. > > If the call to commit() is being made "too soon", such as after each > statement (kind of what happens with autoCommit on), and the host goes > down > between statements, you have to worry about consistency yourself. Consider > a program that withdraws money from one bank account, commits, then > deposits into another account, then commits: if the host goes down between > commits, some money just disappeared. > > On the other hand, if the call to commit() is being made "too late" (only > when the user quits the program, for example), then if the host goes down > before that, none of the new data will be in the database. It will still > be > consistent, but data will have been lost. > > What you need to do is find out what statements (if any) should be grouped > in atomic blocks for your application, then commit() each time one of > those > blocks finish.
What a great explanation, thanks. I just looked at my code and I see that I only do the "conn.setAutoCommit(false)" statement during Database initialization methods[twice]. I do, however do the "conn.commit()" statement in all the methods I have written to perform Database operations. I think that all of these methods only perform one transaction at a time. I'll go back and make sure that is a true statement. I think I just felt that the commit was necessary in my Derby operations code but I do not know why I decided to do the conn.setAutoCommit(false) operation? My derby code is somewhat basic and not to complex but I am thankful for your info in case I need to write something more interesting someday. Regards, Jim... -- View this message in context: http://apache-database.10148.n7.nabble.com/JPA-required-tp127242p127281.html Sent from the Apache Derby Users mailing list archive at Nabble.com.
