How to optimize Database Calls to improve performance of an application

Question

Hi,
I have a performance issue with my applications. It takes a lot of time to load, as it is making several calls to the database. And, moreover, the resultset has more than 2000 records that are returned. I need to know what is the better way to improve the performance
1. What is the solution to optimize the database calls so that I can improve the performance of my application and also improve on the trun around time to load the web pages.
2. Stored procedures are a good way to get the data from the result set iteratively. How can I implement this solution in Java?
This is very important, and any help is greatly appreciated.
Thanks in Advance,
Sailatha

Answer 1

latha_kaps wrote:
I have a performance issue with my applications. It takes a lot of time to load, as it is making several calls to the database. And, moreover, the resultset has more than 2000 records that are returned. I need to know what is the better way to improve the performance
1. What is the solution to optimize the database calls so that I can improve the performance of my application and also improve on the trun around time to load the web pages.
2. Stored procedures are a good way to get the data from the result set iteratively. How can I implement this solution in Java?
This is very important, and any help is greatly appreciated.1. 2000 records inside a resultset are not a big number.
2. Which RDBMS you use?
Concerning the answer to 2. you have different possibilities. The best thing is always to handle as many transactions as possible inside the database. Therefore a stored procedure is the best approach imho.
Below there is an example for an Oracle RDBMS.
Assumption #1 you have created an object (demo_obj) in your Oracle database:
create type demo_obj as object( val1 number, val2 number, val3 number);
create type demo_array as table of demo_obj;
/Assumption #2 you've created a stored function to get the values of the array in your database:
create or replace function f_demo ( p_num number )
return demo_array
as
    l_array demo_array := demo_array();
begin
    select demo_obj(round(dbms_random.value(1,2000)),round(dbms_random.value(2000,3000)),round(dbms_random.value(3000,4000)))
    bulk collect into l_array
      from all_objects
     where rownum <= p_num;
    return l_array;
end;
/For getting the data out of database use the following Java program (please watch the comments):
import java.sql.*;
import java.io.*;
import oracle.sql.*;
import oracle.jdbc.*;
public class VarrayDemo {
     public static void main(String args[]) throws IOException, SQLException {
          DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
          Connection conn = DriverManager.getConnection(
                    "jdbc:oracle:oci:@TNS_ENTRY_OF_YOUR_DB", "scott", "tiger"); // I am using OCI driver here, but one can use thin driver as well
          conn.setAutoCommit(false);
          Integer numRows = new Integer(args[0]); // variable to accept the number of rows to return (passed at runtime)
          Object attributes[] = new Object[3]; // "attributes" of the "demo_obj" in the database
          // the object demo_obj in the db has 3 fields, all numeric
          // create an array of objects which has 3 attributes
          // we are building a template of that db object
          // the values i pass below are just generic numbers, 1,2,3 mean nothing really
          attributes[0] = new Integer(1);
          attributes[1] = new Integer(2);
          attributes[2] = new Integer(3);
          // this will represent the data type DEMO_OBJ in the database
          Object demo_obj[] = new Object[1];
          // make the connection between oracle <-> jdbc type
          demo_obj[0] = new oracle.sql.STRUCT(new oracle.sql.StructDescriptor(
                    "DEMO_OBJ", conn), conn, attributes);
          // the function returns an array (collection) of the demo_obj
          // make the connection between that array(demo_array) and a jdbc array
          oracle.sql.ARRAY demo_array = new oracle.sql.ARRAY(
                    new oracle.sql.ArrayDescriptor("DEMO_ARRAY", conn), conn,
                    demo_obj);
          // call the plsql function
          OracleCallableStatement cs =
               (OracleCallableStatement) conn.prepareCall("BEGIN ? := F_DEMO(?);END;");
          // bind variables
          cs.registerOutParameter(1, OracleTypes.ARRAY, "DEMO_ARRAY");
          cs.setInt(2, numRows.intValue());
          cs.execute();
          // get the results of the oracle array into a local jdbc array
          oracle.sql.ARRAY results = (oracle.sql.ARRAY) cs.getArray(1);
          // flip it into a result set
          ResultSet rs = results.getResultSet();
          // process the result set
          while (rs.next()) {
               // since it's an array of objects, get and display the value of the underlying object
               oracle.sql.STRUCT obj = (STRUCT) rs.getObject(2);
               Object vals[] = obj.getAttributes();
               System.out.println(vals[0] + " " + vals[1] + " " + vals[2]);
          // cleanup
          cs.close();
          conn.close();
}For selecting 20.000 records it takes only a few seconds.
Hth