Java Stored Procedure in .NET Assign EAN-13 Supplement 2 in .NET Java Stored Procedure

Java Stored Procedure generate, create ean13+5 none on .net projects iReport for Jasper Server Elapsed Time (s). FIGURE 12-16 Java integer arithmetic compared to various PL/SQL alternatives. Using and Tuning PL/SQL PL/SQL function i n memory and, if the function is expensive to resolve, can retrieve the results for the function from memory more efficiently than by reexecuting the function. You might want to use the function cache in the following circumstances: You have a computationally expensive function that is deterministic: It will always return the same results given the same inputs. You have a database access routine encapsulated in a function that accesses tables that are infrequently updated.

. The prime number EAN-13 for .NET function we introduced previously in this chapter is a good example of the first type of function. It is expensive to calculate but will always return the same outputs given the same inputs.

To take advantage of the function cache, we add the RESULT_CACHE clause to our function definition. For our prime number function, we would add the clause as follows: CREATE OR REPLACE FUNCTION nprimes1_rc (p_num NUMBER) RETURN NUMBER RESULT_CACHE IS For SQL statements that access the database, you also will want to include the RELIES clause. This lets Oracle know that changes to the data in the specified table invalidate the cached results.

For instance, the following function retrieves sales totals for the last specified number of days: CREATE OR REPLACE FUNCTION time_sales_rc (p_days NUMBER) RETURN NUMBER RESULT_CACHE RELIES_ON(sh.sales) IS v_amount_sold NUMBER; BEGIN SELECT SUM (amount_sold) INTO v_amount_sold FROM sh.sales WHERE time_id>sysdate-numtodsinterval(p_days,"DAY"); return(v_amount_sold); END; The SH.

SALES table might be updated infrequently (perhaps overnight), and caching the function could avoid expensive lookups should the function be issued with the same arguments between data loads. Figure 12-17 shows the effect of implementing the function cache on this function for 100 executions with random date ranges between 1 to 30 days..

12 . 5.21 No Function Cache 1.51 Function Cache Elapsed Time (s). FIGURE 12-17 Example of Oracle 11g function cache performance. Oracle 11g PL/SQL GS1-13 for .NET function cache can result in large improvements for expensive but deterministic functions, or for data access functions on static tables..

The Oracle 11g fu nction cache is part of the more general result set cache that we discuss in detail in 20, Other Memory Management Topics. . DML TRIGGER PERFORMANCE DML Triggers are PL/SQL programs that execute whenever DML operations alter the contents of a table. They can be used to validate data, enforce business rules, or to automatically implement denormalization and nondeclarative referential integrity. Because trigger code can create an overhead on DML statements, it s critical to ensure that the trigger code is executed only when absolutely necessary.

UPDATE OF AND WHEN CLAUSES The UPDATE OF clause of the CREATE TRIGGER statement allows a FOR UPDATE trigger to fire only when the nominated columns are updated. In a similar way, the WHEN clause can prevent the execution of the trigger unless a logical condition is met. These clauses help to prevent the trigger from executing unnecessarily and can improve performance of DML operations on the table in which the trigger is based.

. Using and Tuning PL/SQL For example, the following trigger fires whenever any column in the SALES table is updated, even though it does nothing unless the new AMOUNT_SOLD value is greater than 1500: CREATE OR REPLACE TRIGGER sales_upd BEFORE UPDATE OR INSERT ON sales FOR EACH ROW DECLARE v_adjusted_amount sales.amount_sold%TYPE; BEGIN v_adjusted_amount := sales_discount (:new.amount_sold); IF :new.

amount_sold > 1500 THEN :new.amount_sold := v_adjusted_amount; END IF; END; The following trigger is more efficient because it fires only when the AMOUNT_SOLD column is updated and only when the new value of AMOUNT_SOLD is greater than $1,500: CREATE OR REPLACE TRIGGER sales_upd BEFORE UPDATE OF amount_sold OR INSERT ON sales FOR EACH ROW WHEN (new.amount_sold > 1500) DECLARE v_adjusted_amount sales.

amount_sold%TYPE; BEGIN v_adjusted_amount := sales_discount (:new.amount_sold); IF :new.amount_sold > 1500 THEN :new.

amount_sold := v_adjusted_amount; END IF; END; Figure 12-18 shows that for an example workload, the WHEN and UPDATE OF clauses significantly improved performance.. Make use of the O ean13+5 for .NET F columns and WHEN clauses of the CREATE TRIGGER statement to ensure that your trigger fires only when necessary..

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