VA Smalltalk uses an optimistic locking policy for database queries that modify the database. After you execute a query, no locks are held in the database manager for the result table. If your application updates the result table and then applies the changes, the database will be updated, even if it has been modified by another user since you first retrieved your result table.

If someone else deleted a row that you are trying to update, your changes cannot be applied, and an error is returned.

A cursor is opened to lock the current row of the result table. When the current row changes, the cursor is closed on the previous row and opened on the new row.

Usually, closing the cursor releases the lock, but some database managers (such as Oracle) do not release locks until a commit or a rollback. In this case, be sure to select Auto commit so as not to lock so many rows at a time.