However, the first statement is slower because it does a time-consuming full scan of the EMP table for every department number in the DEPT table. A third cause of poor performance is unnecessary parsing and binding. Recall that before executing a SQL statement, Oracle8 must parse and bind it. Parsing means examining the SQL statement to make sure it follows syntax rules and refers to valid database objects. Binding means associating host variables in the SQL statement with their addresses so that Oracle8 can read or write their values.
Many applications manage cursors poorly.
This results in unnecessary parsing and binding, which adds noticeably to processing overhead. If you are unhappy with the performance of your precompiled programs, there are several ways you can reduce overhead. Using Host Tables Host tables can boost performance because they let you manipulate an entire collection of data with a single SQL statement. For example, suppose you want to insert salaries for 300 employees into the EMP table. Without tables your program must do 300 individual inserts-one for each employee.