HP 3000 Manuals HP 3000 Manuals
Using Procedures and Rules Stored procedures, used independently or invoked by rules, can improve performance in the DBEnvironment. For applications that access a local DBEnvironment, combining multiple SQL statements and logic in a stored procedure can improve performance by reducing the overhead of multiple calls to SQLCore. For applications that operate on a remote DBEnvironment or in a client/server environment, each call to SQLCore must travel across the network. In this environment, the use of stored procedures can dramatically reduce network traffic and thus improve performance. It is generally better to place conditions in the FiringCondition of a rule rather than including them as conditional statements within the procedure invoked by the rule, to minimize the overhead of procedure execution. The specification of a FiringCondition minimizes overhead by avoiding unnecessary procedure calls. For each row affected by the statement, the FiringCondition is tested, and the procedure is invoked only when the FiringCondition is satisfied. Thus, the specification of a FiringCondition can improve the performance of data manipulation operations on the table on which the rule is defined. Since a procedure executed by a rule may itself execute statements that fire rules, the developer should carefully analyze the relationships among rules and the procedures invoked by rules to ensure that the performance implications on data manipulation statements that fire a chain of rules are well understood.