Savepoint, rollback and viewstate

I just came to know about how view state affects the buddies savepoint and rollback so just wanted to share about it.

Every time a page is called, it goes through a particular set of actions. One entire set of actions is a single transaction. When you view the page, Salesforce goes through a series of actions, which generally looks like the following:


1) Load the appropriate classes into memory, initialize memory heap, use an implied Database.setSavePoint().

2) If the View State is empty (i.e. you are visiting the page the first time), call the page's constructor methods.

3) If View State is not empty, load those memory variables into the object (deserialization).

4) If View State is not empty, call each of the Setter methods for all values that were rendered into the form from the last action.

5) If an "action" was called, perform the action.

6) Call the getter methods and render the page's output.

7) Set the view state for the form and output the total results (Serialization).

8) Call the implied Database.commit() if nothing went wrong in any prior step.


(These may not be precise order). A transaction is started before each page action, and completed at the end of each action.


Every time you call back to the server, it is one complete transaction. For example, if you press a "Next" button, then press a "Save" button, even though you're on the same page, with the same view state throughout, you've had three distinct database transactions (the initial load, the Next action, and the Save action). You can't roll back changes between each transaction, because the transaction is already complete.



This is the same inherent design with every major RDBMS out there on the market-- when one whole transaction is done, the data is committed. In every major database out there, each page served results in one entire transaction.


While View State can hold almost any data, the database can't place the transaction in a holding pattern indefinitely. It must immediately commit or rollback the entire transaction before the end of a single transaction unit, and the default is to commit unless there is an uncaught exception or error that causes it to rollback automatically, or the programmer manually rolls back a transaction.

While using savePoint and Rollback make sure that you are using it in same view state or else savepoint will change to null and it will give argument passed cannot be null at line database.commit().