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JAVA JDBC SQL updating a new database based on the old database records

I am trying to write a runnable jar file that can be able to connect to 2 different databases informix old database and oracle new database. It should be able to update the new database(oracle) with the old database(informix) records.
I re-edit my java code I added separate methods for my select, update and connections I am not getting an error but its not updating my db. My select works but my update statement is not working. This is my result i get - SELECT profile_id, ingress_flag, egress_flag, ce_ingress_flag, ce_egress_flag from COS_PROFILE where profile_id = 102
profileid : 102
ingressflag : Y
egress_flag : Y
ceingressflag : Y
ceegressflag : Y
ResultSet not open, operation 'next' not permitted. Verify that autocommit is OFF
I am not sure how can I fixed the ResultSet not open, operation 'next' not permitted. Verify that autocommit is OFF
public class TestConnection {
static ResultSet rs;
public static void main (String[] args) throws Exception {
try{
selectRecordsIcore();
updateRecordIntoBids();
} catch (SQLException e) {
System.out.println(e.getMessage());
}
}
public static void selectRecordsIcore() throws SQLException {
Connection dbConnection = null;
Statement statement = null;
String selectTableSQL = "SELECT profile_id, ingress_flag, egress_flag, ce_ingress_flag, ce_egress_flag from COS_PROFILE";
try {
dbConnection = getInformixConnection();
statement = dbConnection.createStatement();
System.out.println(selectTableSQL);
// execute select SQL stetement
rs = statement.executeQuery(selectTableSQL);
while (rs.next()) {
int profileid = rs.getInt("profile_id");
String ingressflag = rs.getString("ingress_flag");
String egress_flag = rs.getString("egress_flag");
String ceingressflag = rs.getString("ce_ingress_flag");
String ceegressflag = rs.getString("ce_egress_flag");
System.out.println("profileid : " + profileid);
System.out.println("ingressflag : " + ingressflag);
System.out.println("egress_flag : " + egress_flag);
System.out.println("ceingressflag : " + ceingressflag);
System.out.println("ceegressflag : " + ceegressflag);
}
} catch (SQLException e) {
System.out.println(e.getMessage());
} finally {
if (statement != null) {
statement.close();
}
if (dbConnection != null) {
dbConnection.close();
}
}
}
private static void updateRecordIntoBids() throws SQLException {
Connection dbConnection = null;
Statement statement = null;
ArrayList<TempStorageRecords> updateSQL = new ArrayList<TempStorageRecords>();
while (rs.next()) {
int profileid = rs.getInt("profile_id");
String ingressflag = rs.getString("ingress_flag");
String egress_flag = rs.getString("egress_flag");
String ceingressflag = rs.getString("ce_ingress_flag");
String ceegressflag = rs.getString("ce_egress_flag");
String updateTableSQL = "UPDATE traffic_profile SET ingress_flag = " + ingressflag
+ " ,egress_flag = " + egress_flag
+ " ,ce_ingress_flag = " + ceingressflag
+ " ,ce_egress_flag = " + ceegressflag
+ " WHERE profile_id = " + profileid + ";";
try {
dbConnection = getOracleConnection();
statement = dbConnection.createStatement();
System.out.println("updateTableSQL 1 :" + updateTableSQL);
// execute update SQL stetement
statement.execute(updateTableSQL);
System.out.println("updateTableSQL 2: " + updateTableSQL);
} catch (SQLException e) {
System.out.println(e.getMessage());
} finally {
if (statement != null) {
statement.close();
}
if (dbConnection != null) {
dbConnection.close();
}
}
}
}
public static Connection getOracleConnection() throws SQLException {
String driver = "oracle.jdbc.driver.OracleDriver";
String url = "jdbc:oracle:thin:#oracle_host:1521:BIDS";
String username = "username";
String password = "password";
try {
Class.forName(driver);
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} // load Oracle driver
Connection dbConnection = null;
try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
System.out.println(e.getMessage());
}
try {
dbConnection = DriverManager.getConnection(
url, username,password);
return dbConnection;
} catch (SQLException e) {
System.out.println(e.getMessage());
}
return dbConnection;
}
public static Connection getInformixConnection() throws SQLException {
String driver = "com.informix.jdbc.IfxDriver";
String url = "jdbc:informix-sqli://informix_host:1615/icore:INFORMIXSERVER=icit";
String username = "user";
String password = "pass";
try {
Class.forName(driver);
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} // load Informix driver
Connection dbConnection = null;
try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
System.out.println(e.getMessage());
}
try {
dbConnection = DriverManager.getConnection(
url, username,password);
return dbConnection;
} catch (SQLException e) {
System.out.println(e.getMessage());
}
return dbConnection;
}
}

At first try to export data from source database into text file.
Your code uses hard coded column names, but I think it could read table names to export from some config file and column names from metadata from SELECT * FROM [table_name]. In JDBC there is getMetaData() for RecordSet. Use it.
When you export data into text files without problems you can do the next step: import such data directly from the source database to the destination database.
For destination database create prepareStatement with:
'INSERT INTO ' + table_name_dest + ' (' + column_names +') VALUES ('+ question_marks + ')'
(there question_marks are '?' chars which maps to columns).
Then for each record from source table and for each record (row) do:
insert_stmt.setObject(i, rs_in.getObject(i))
For big tables you can also use setFetchSize() and addBatch()/executeBatch()

Glassfish Closing JDBC Connection

I am new to Glassfish and Java EE, and I try to develop a project using glassfish as the server. The problem I have is that sometiems glassfish takes too long to deploy the project because it is closing JDBC Connections, and that takes too long.
SEVERE: Closing JDBC Connection 0
SEVERE: Closing JDBC Connection 1
SEVERE: Closing JDBC Connection 2
SEVERE: Closing JDBC Connection 3
SEVERE: Closing JDBC Connection 4
...........
SEVERE: Closing JDBC Connection 19
I don't know if the problem is from the glassfish server or from my code.. I am closing the connections after using them..
Can you please help me with figuring out where the problem comes from and how can I solve it?
I will add some more info.
I am using GlassFish Server 4.1 and Java EE 7 Web.
For connections, I have the following classes:
public class PooledConnection {
private Connection connection = null;
private boolean inuse = false;
// Constructor that takes the passed in JDBC Connection
// and stores it in the connection attribute.
public PooledConnection(Connection value) {
if (value != null) {
this.connection = value;
}
}
// Returns a reference to the JDBC Connection
public Connection getConnection() {
// get the JDBC Connection
return this.connection;
}
// Set the status of the PooledConnection.
public void setInUse(boolean value) {
inuse = value;
}
//Returns the current status of the PooledConnection.
public boolean inUse() {
return inuse;
}
// Close the real JDBC Connection
public void close() {
try {
connection.close();
} catch (SQLException sqle) {
System.err.println(sqle.getMessage());
}
}
}
The ConnectionPool class
public class ConnectionPool {
// JDBC Driver Name
private String driver = null;
// URL of database
private String url = null;
// Initial number of connections.
private int size = 0;
// Username
private String username = null;
// Password
private String password = null;
// Vector of JDBC Connections
private ArrayList<PooledConnection> pool = null;
private ArrayList<PooledConnection> poolInUse = null;
private ArrayList<PooledConnection> poolNotInUse = null;
public ConnectionPool() {
}
// Set the value of the JDBC Driver
public void setDriver(String value) {
if (value != null) {
driver = value;
}
}
// Get the value of the JDBC Driver
public String getDriver() {
return driver;
}
// Set the URL Pointing to the Datasource
public void setURL(String value) {
if (value != null) {
url = value;
}
}
// Get the URL Pointing to the Datasource
public String getURL() {
return url;
}
// Set the initial number of connections
public void setSize(int value) {
if (value > 1) {
size = value;
}
}
// Get the initial number of connections
public int getSize() {
return size;
}
// Set the username
public void setUsername(String value) {
if (value != null) {
username = value;
}
}
// Get the username
public String getUserName() {
return username;
}
// Set the password
public void setPassword(String value) {
if (value != null) {
password = value;
}
}
// Get the password
public String getPassword() {
return password;
}
// Creates and returns a connection
private Connection createConnection() throws Exception {
Connection con = null;
// Create a Connection
con = DriverManager.getConnection(url, username, password);
return con;
}
// Initialize the pool
public synchronized void initializePool() throws Exception {
// Check our initial values
if (driver == null) {
throw new Exception("No Driver Name Specified!");
}
if (url == null) {
throw new Exception("No URL Specified!");
}
if (size < 1) {
throw new Exception("Pool size is less than 1!");
}
// Create the Connections
try {
// Load the Driver class file
Class.forName(driver);
// Create Connections based on the size member
for (int x = 0; x < size; x++) {
System.err.println("Opening JDBC Connection " + x);
Connection con = createConnection();
if (con != null) {
// Create a PooledConnection to encapsulate the real JDBC Connection
PooledConnection pcon = new PooledConnection(con);
// Add the Connection to the pool
addConnection(pcon);
}
}
} catch (SQLException sqle) {
System.err.println(sqle.getMessage());
} catch (ClassNotFoundException cnfe) {
System.err.println(cnfe.getMessage());
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
// Adds the PooledConnection to the pool
private void addConnection(PooledConnection value) {
// If the pool is null, create a new vector with the initial size of
if(pool == null)
{
pool = new ArrayList<PooledConnection>(size);
}
pool.add(value);
}
public synchronized void releaseConnection(Connection con)
{
if(con != null)
{
// find the PooledConnection Object
for (int x = 0; x < pool.size(); x++) {
PooledConnection pcon = pool.get(x);
// Check for correct Connection
if (pcon.getConnection() == con) {
System.err.println("Releasing Connection " + x);
// Set its inuse attribute to false, which
// releases it for use
pcon.setInUse(false);
break;
}
}
}
}
// Find an available connection
public synchronized Connection getConnection() throws Exception {
PooledConnection pcon = null;
// find a connection not in use
for (int x = 0; x < pool.size(); x++) {
pcon = pool.get(x);
// Check to see if the Connection is in use
if (pcon.inUse() == false) {
// Mark it as in use
pcon.setInUse(true);
// return the JDBC Connection stored in the
// PooledConnection object
return pcon.getConnection();
}
}
// Could not find a free connection, create and add a new one
try {
// Create a new JDBC Connection
Connection con = createConnection();
// Create a new PooledConnection, passing it the JDBC Connection
pcon = new PooledConnection(con);
// Mark the connection as in use
pcon.setInUse(true);
// Add the new PooledConnection object to the pool
pool.add(pcon);
} catch (Exception e) {
System.err.println(e.getMessage());
}
// return the new Connection
return pcon.getConnection();
}
// When shutting down the pool, you need to first empty it.
public synchronized void emptyPool() {
// Iterate over the entire pool closing the JDBC Connections.
for (int x = 0; x < pool.size(); x++) {
System.err.println("Closing JDBC Connection " + x);
PooledConnection pcon = pool.get(x);
// If the PooledConnection is not in use, close it
if (pcon.inUse() == false) {
pcon.close();
} else {
// If it is still in use, sleep for 30 seconds and force close.
try {
java.lang.Thread.sleep(30000);
pcon.close();
} catch (InterruptedException ie) {
System.err.println(ie.getMessage());
}
}
}
}
}
And the DBAccessController
public final class DBAccessController {
private Connection connection = null;
public DBAccessController(String url, String userId, String password, boolean typereadonly) {
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
connection = DriverManager.getConnection(url, userId, password);
connection.setReadOnly(typereadonly);
} catch (java.lang.ClassNotFoundException exceptionClassNotFound) {
} catch (java.lang.InstantiationException instantException) {
} catch (java.lang.IllegalAccessException illegalAccess) {
} catch (java.sql.SQLException sqle) {
}
}
public DBAccessController(Connection con) {
if (con != null) {
this.connection = con;
}
}
public final synchronized ArrayList runSQL(String queryString, List<String> parametrii) {
try {
PreparedStatement prepStmt = connection.prepareStatement(queryString, PreparedStatement.RETURN_GENERATED_KEYS);
connection.setAutoCommit(true);
for (int i = 0; i < parametrii.size(); i++) {
prepStmt.setString((i + 1), parametrii.get(i));
}
ResultSet rs = prepStmt.executeQuery();
boolean flag = prepStmt.execute();
ArrayList<HashMap<String, String>> rezultate = new ArrayList<>();
ResultSet keyset = prepStmt.getGeneratedKeys();
while (keyset != null && keyset.next()) {
HashMap<String, String> keysHM = new HashMap<>();
// Retrieve the auto generated key(s).
int key = keyset.getInt(1);
keysHM.put("cheia", Integer.toString(key));
rezultate.add(keysHM);
}
if (flag) {
ResultSet res = prepStmt.getResultSet();
ResultSetMetaData rsmd = res.getMetaData();
int numberOfColumns = rsmd.getColumnCount();
while (res.next()) {
HashMap<String, String> hm = new HashMap<>();
Object o = res.getObject(i);
if (o != null) {
hm.put(rsmd.getColumnName(i), o.toString());
}
}
rezultate.add(hm);
}
res.close();
prepStmt.close();
return rezultate;
} else {
prepStmt.close();
if (keyset != null) {
return rezultate;
} else {
return null;
}
}
} catch (java.sql.SQLException sqle) {
return null;
}
}
public final synchronized ArrayList runSQL(String queryString) {
try {
PreparedStatement statement = connection.prepareStatement(queryString, PreparedStatement.RETURN_GENERATED_KEYS);
connection.setAutoCommit(true);
boolean flag = statement.execute();
System.out.println("Statement: " + statement + " flag: " + flag);
ArrayList<HashMap<String, String>> rezultate = new ArrayList<>();
ResultSet keyset = statement.getGeneratedKeys();
while (keyset != null && keyset.next()) {
HashMap<String, String> keysHM = new HashMap<>();
// Retrieve the auto generated key(s).
int key = keyset.getInt(1);
keysHM.put("cheia", Integer.toString(key));
rezultate.add(keysHM);
System.out.println("Cheile " + keyset.toString());
}
System.out.println("Cheile " + keyset.toString());
if (flag) {
ResultSet res = statement.getResultSet();
ResultSetMetaData rsmd = res.getMetaData();
int numberOfColumns = rsmd.getColumnCount();
System.out.println("res: " + res + " rsmd: " + rsmd + " numberOfColumns: " + numberOfColumns);
while (res.next()) {
HashMap<String, String> hm = new HashMap<>();
System.out.println("Res to string " + res.toString());
for (int i = 1; i <= numberOfColumns; i++) {
System.out.println("obiectul " + i + " res.getObject(i) " + res.getObject(i));
Object o = res.getObject(i);
System.out.println("rsmd.getColumnName(i) " + rsmd.getColumnName(i));
if (o != null) {
hm.put(rsmd.getColumnName(i), o.toString());
}
}
rezultate.add(hm);
}
res.close();
statement.close();
System.out.println("Return rezultate");
return rezultate;
} else {
System.out.println("Return null 1");
statement.close();
if (keyset != null) {
return rezultate;
} else {
return null;
}
}
} catch (java.sql.SQLException sqle) {
System.out.println("Return null 2" + sqle.getMessage());
return null;
}
}
public final void stop() {
try {
connection.close();
} catch (java.sql.SQLException e) {
}
}
}
When I need to use a connection I do the following (for example):
Connection con;
try {
con = cp.getConnection();
udao = new UtilizatorDAO(con);
con.close();
}
} catch (Exception ex) {
Logger.getLogger(RegisterController.class.getName()).log(Level.SEVERE, null, ex);
}
out.close();

Deferencing Null pointer

public class Model
{
public static Connection getConnection()
{
Connection conn = null;
try
{
Class.forName("oracle.jdbc.OracleDriver");
conn = DriverManager.getConnection("jdbc:oracle:thin:#localhost:1521:xe", "System", "system");
}
catch(ClassNotFoundException e)
{
e.printStackTrace();
}
catch(SQLException e)
{
e.printStackTrace();
}
return conn;
}
public static class Cart
{
public String itmName="";
public int howmany=0;
public static long itmQty=0, itmID=0;
public double itmPrice=0.0, itmCost=0.0, totalSum=0.0;
}
public static ArrayList<Cart> getCartDatabase(String user) throws Exception
{
Connection conn = getConnection();
String sql = "select * from userCarts where userID = '" + user + "'";
PreparedStatement pstmt = conn.prepareStatement(sql);
ResultSet rst = pstmt.executeQuery();
ArrayList<Cart> al = null;
Cart crt=null;
while(rst.next())
{
System.out.println("CPoint");
try
{
long p = rst.getLong("itemID");
crt.itmID = p; // This is the line thats creating the error
System.out.println(p + " is long! I guess...");
}
catch(NullPointerException e)
{
System.out.println("NPE Caught in Model");
}
System.out.println("CP 1 " + crt.itmID);
ArrayList<row> alr=null;
try
{
alr = Model.getStoreInventory();
}
catch(Exception e)
{
e.printStackTrace();
}
System.out.println("CP 2");
for(int i=0; i<alr.size(); i++)
{
crt.itmName = alr.get(i).itmName;
crt.itmPrice = alr.get(i).itmPrice;
crt.itmQty = alr.get(i).itmQty;
}
System.out.println("CP 3");
crt.howmany = rst.getInt("howmany");
crt.itmCost = crt.itmPrice*crt.howmany;
al.add(crt);
}
return al;
}
}
When I try to access this method of getCartFromDatabase, it gives a NullPointerException however I don't understand why it would do this. Moreover, I tried to make the class as a non static class too, but still it gave the same error:
"Possible deferencing Null Pointer"

Cart crt=null;
while(rst.next())
{
System.out.println("CPoint");
try
{
long p = rst.getLong("itemID");
crt.itmID = p; // This is the line thats creating the error
System.out.println(p + " is long! I guess...");
}
crt is null when you try to access crt.itemID. You have to assign it an instance first.
I think you may simply change the first line from the snippet to
Cart crt = new Cart();

Using profiling tool to find the exact reason for outOfMemoryError in the java code

Hi i have a java program for accessing remote as well as local databases at the same time using JDBC.
But i am getting this exception:
->Exception in thread "Thread-1964" java.lang.OutOfMemoryError: Java heap space
Now i wanted to use any profiling tool through whic i can get exact reason for this exception in my code.
This is my java program
public class DBTestCases{
Connection localConnection;
Connection remoteConnection;
Connection localCon;
Connection remoteCon;
List<Connection> connectionsList;
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String password = "root";
String dbName = "myDB";
String connectionUrl1= "jdbc:mysql://11.232.33:3306/"+dbName+"?user="+user+"&password="+password+"&useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&maxReconnects=10";
String connectionUrl2= "jdbc:mysql://localhost:3306/"+dbName+"?user="+user+"&password="+password+"&useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&maxReconnects=10";
public List<Connection> createConnection() {
try {
Class.forName(driver);
localCon = DriverManager.getConnection(connectionUrl2);
if(localCon != null)
System.out.println("connected to remote database at : "+new Date());
remoteCon = DriverManager.getConnection(connectionUrl1);
if(remoteCon != null)
System.out.println("connected to local database at : "+new Date());
connectionsList = new ArrayList<Connection>( 2 );
connectionsList.add( 0 , localCon );
connectionsList.add( 1 , remoteCon );
} catch(ClassNotFoundException cnfe) {
cnfe.printStackTrace();
} catch(SQLException sqle) {
sqle.printStackTrace();
}
return connectionsList;
}
public void insert(){
Runnable runnable = new Runnable(){
public void run() {
PreparedStatement ps1 = null;
PreparedStatement ps2 = null;
String sql = "insert into user1(name, address, created_date)" +
" values('johnsan', 'usa', '2013-08-04')";
if(remoteConnection != null&&localConnection != null) {
System.out.println("Database Connection Is Established");
try {
ps1 = remoteConnection.prepareStatement(sql);
ps2 = localConnection.prepareStatement(sql);
int i = ps1.executeUpdate();
int k = ps2.executeUpdate();
if(i > 0) {
System.out.println("Data Inserted into remote database table Successfully");
}
if(k > 0) {
System.out.println("Data Inserted into local database table Successfully");
}
} catch (SQLException s) {
System.out.println("SQL code does not execute.");
s.printStackTrace();
}catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Inserting values in db");
}
};
Thread thread = new Thread(runnable);
thread.start();
}
public void retrieve(){
Runnable runnable = new Runnable(){
public void run() {
try {
Statement st1 = localConnection.createStatement();
Statement st2 = remoteConnection.createStatement();
ResultSet res1 = st1.executeQuery("SELECT * FROM user1");
ResultSet res2 = st2.executeQuery("SELECT * FROM user1");
System.out.println("---------------------------Local Database------------------------");
while (res1.next()) {
Long i = res1.getLong("userId");
String s1 = res1.getString("name");
String s2 = res1.getString("address");
java.sql.Date d = res1.getDate("created_date");
System.out.println(i + "\t\t" + s1 + "\t\t" + s2 + "\t\t"+ d);
}
System.out.println("------------------------Remote Database---------------------");
while (res2.next()) {
Long i = res2.getLong("userId");
String s1 = res2.getString("name");
String s2 = res2.getString("address");
java.sql.Date d = res2.getDate("created_date");
System.out.println(i + "\t\t" + s1 + "\t\t" + s2 + "\t\t"+ d);
}
} catch (SQLException s) {
System.out.println("SQL code does not execute.");
s.printStackTrace();
}catch (Exception e) {
e.printStackTrace();
}
}
};
Thread thread = new Thread(runnable);
thread.start();
}
public static void main(String[] args) {
DBTestCases dbTestCases = new DBTestCases();
List l = dbTestCases.createConnection();
dbTestCases.localConnection = (Connection)l.get(0);
dbTestCases.remoteConnection = (Connection)l.get(1);
for(;;) {
dbTestCases.insert();
dbTestCases.countRows();
dbTestCases.retrieve();
}
}
}
PLease can anybody help me which is the best tool to use and how i have to use it,and any links for this.i am using linux operating system.
I think i am starting a new thread for each call of method can anybody suggest how to close thread before starting it again or use thred pool..
Thankyou in advance.

The same problem has happened to me once. The problem is your java reserved heap memory. This heap memory is configurable through one of the java config files; both it's minimum and maximum amount.

There are a lots of profilers.
I have been using Visual VM for a while and that's useful for me, at least. It's easy to use and pretty powerful tool as well.
Here's the link:
http://visualvm.java.net
Not sure which IDE you are using. But there's nothing do do with OutOfMemoryError which mean that it's a RuntimeException.

A little bit of offtopic (because I'm not going to suggest you a profiler), but the problem, I think, comes from these lines
ps1 = remoteConnection.prepareStatement(sql);
ps2 = localConnection.prepareStatement(sql);
int i = ps1.executeUpdate();
int k = ps2.executeUpdate();
and
Statement st1 = localConnection.createStatement();
Statement st2 = remoteConnection.createStatement();
ResultSet res1 = st1.executeQuery("SELECT * FROM user1");
ResultSet res2 = st2.executeQuery("SELECT * FROM user1");
After you create PreparedStatement and use it, you should close it. Either you should use close() method when you don't need it anymore or use try-with-resources (it use close() automatically). Java Tutorial on statements and on try-with-resources. Also consider reading this and this topics.
A would rewrite your code something like this (didn't actually tried it, but it compiles and it supposed to eliminate problems with memory leaks):
public class DBTestCases {
Connection localConnection;
Connection remoteConnection;
Connection localCon;
Connection remoteCon;
List<Connection> connectionsList;
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String password = "root";
String dbName = "myDB";
String connectionUrl1= "jdbc:mysql://11.232.33:3306/"+dbName+"?user="+user+"&password="+password+"&useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&maxReconnects=10";
String connectionUrl2= "jdbc:mysql://localhost:3306/"+dbName+"?user="+user+"&password="+password+"&useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&maxReconnects=10";
public List<Connection> createConnection() {
try {
Class.forName(driver);
localCon = DriverManager.getConnection(connectionUrl2);
if(localCon != null)
System.out.println("connected to remote database at : "+new Date());
remoteCon = DriverManager.getConnection(connectionUrl1);
if(remoteCon != null)
System.out.println("connected to local database at : "+new Date());
connectionsList = new ArrayList<Connection>( 2 );
connectionsList.add( 0 , localCon );
connectionsList.add( 1 , remoteCon );
} catch(ClassNotFoundException cnfe) {
cnfe.printStackTrace();
} catch(SQLException sqle) {
sqle.printStackTrace();
}
return connectionsList;
}
public void insert(){
Runnable runnable = new Runnable(){
public void run() {
PreparedStatement ps1 = null;
PreparedStatement ps2 = null;
String sql = "insert into user1(name, address, created_date)" +
" values('johnsan', 'usa', '2013-08-04')";
if(remoteConnection != null&&localConnection != null) {
System.out.println("Database Connection Is Established");
try {
ps1 = remoteConnection.prepareStatement(sql);
ps2 = localConnection.prepareStatement(sql);
int i = ps1.executeUpdate();
int k = ps2.executeUpdate();
if(i > 0) {
System.out.println("Data Inserted into remote database table Successfully");
}
if(k > 0) {
System.out.println("Data Inserted into local database table Successfully");
}
} catch (SQLException s) {
System.out.println("SQL code does not execute.");
s.printStackTrace();
}catch (Exception e) {
e.printStackTrace();
} finally {
if (ps1 != null) {
try {
ps1.close();
} catch (SQLException ex) {
System.out.println("Cannot close ps1 statement.");
}
}
if (ps2 != null) {
try {
ps2.close();
} catch (SQLException ex) {
System.out.println("Cannot close ps2 statement.");
}
}
}
}
System.out.println("Inserting values in db");
}
};
Thread thread = new Thread(runnable);
thread.start();
}
public void retrieve(){
Runnable runnable = new Runnable(){
public void run() {
Statement st1 = null;
Statement st2 = null;
ResultSet res1 = null;
ResultSet res2 = null;
try {
st1 = localConnection.createStatement();
st2 = remoteConnection.createStatement();
res1 = st1.executeQuery("SELECT * FROM user1");
res2 = st2.executeQuery("SELECT * FROM user1");
System.out.println("---------------------------Local Database------------------------");
while (res1.next()) {
Long i = res1.getLong("userId");
String s1 = res1.getString("name");
String s2 = res1.getString("address");
java.sql.Date d = res1.getDate("created_date");
System.out.println(i + "\t\t" + s1 + "\t\t" + s2 + "\t\t"+ d);
}
System.out.println("------------------------Remote Database---------------------");
while (res2.next()) {
Long i = res2.getLong("userId");
String s1 = res2.getString("name");
String s2 = res2.getString("address");
java.sql.Date d = res2.getDate("created_date");
System.out.println(i + "\t\t" + s1 + "\t\t" + s2 + "\t\t"+ d);
}
} catch (SQLException s) {
System.out.println("SQL code does not execute.");
s.printStackTrace();
}catch (Exception e) {
e.printStackTrace();
} finally {
if (res1 != null) {
try {
res1.close();
} catch (SQLException ex) {
System.out.println("Cannot close res1 result set.");
}
}
if (st1 != null) {
try {
st1.close();
} catch (SQLException ex) {
System.out.println("Cannot close st1 statement.");
ex.printStackTrace();
}
}
if (res2 != null) {
try {
res2.close();
} catch (SQLException ex) {
System.out.println("Cannot close res2 result set.");
}
}
if (st2 != null) {
try {
st2.close();
} catch (SQLException ex) {
System.out.println("Cannot close st2 statement.");
ex.printStackTrace();
}
}
}
}
};
Thread thread = new Thread(runnable);
thread.start();
}
public static void main(String[] args) {
DBTestCases dbTestCases = new DBTestCases();
List l = dbTestCases.createConnection();
dbTestCases.localConnection = (Connection)l.get(0);
dbTestCases.remoteConnection = (Connection)l.get(1);
for(;;) {
dbTestCases.insert();
dbTestCases.countRows();
dbTestCases.retrieve();
}
}
}
There is also another problem with these statements:
ResultSet res1 = st1.executeQuery("SELECT * FROM user1");
ResultSet res2 = st2.executeQuery("SELECT * FROM user1");
I should never (with very rare exceptions) read entire table without using conditions in WHERE. Also if you need only one column created_date, then you must rewrite it like this:
ResultSet res1 = st1.executeQuery("SELECT created_date FROM user1");
ResultSet res2 = st2.executeQuery("SELECT created_date FROM user1");
But I didn't actually replaced it in a full listing, because it can be just 'quick and dirty' code. :)

Efficiently Handling a ResultSet

I'm trying to fetch the results from a database using jdbc connectivity. My result set is made of more than 60,000 rows which I'm then iterating to build a list for comparison with another list object of similar size. Problem is that while this approach gives the correct result, it's very slow. Any ideas as two how to speed it up ? The code sample is given below:
public class PerformanceTest {
//create a connection
Connection getConnection(String uName, String pwd, String url) throws ClassNotFoundException, SQLException
{
Properties info = new Properties();
info.setProperty("user", uName);
info.setProperty("password", pwd);
try
{
Class.forName("oracle.jdbc.driver.OracleDriver");
return DriverManager.getConnection(url, info);
}
catch (ClassNotFoundException e)
{
throw e;
}
catch (SQLException e)
{
throw e;
}
}
//Fetch the records and put them in a map with schema name as key and table name as value
public List<String> fetchRecords(Connection conn, String sql) throws SQLException
{
Statement stmt;
ResultSet rs;
String tableName;
List<String> tableList;
long startTime;
int i=0;
if(conn!=null)
{
try
{
tableList = new ArrayList<String>();
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
startTime = System.currentTimeMillis();
while(rs.next())
{
System.out.println(++i);
tableName = rs.getString(1);
tableList.add(tableName);
}
System.out.println("Running Time: " + (System.currentTimeMillis() - startTime)/1000 + " seconds");
return tableList;
}
catch(SQLException e)
{
throw e;
}
}
else
{
return null;
}
}
public boolean main() throws ClassNotFoundException, SQLException
{
String url = "jdbc:oracle:thin:#xxxxxx:1521:xxxxx";
Connection conn = getConnection("", "", url);
String sql = "SELECT table_name FROM user_tables";
long startTime;
boolean result;
List<String> l1 = fetchRecords(conn, sql);
List<String> l2 = new ArrayList<String>(l1);
//l2.add("1");
startTime = System.currentTimeMillis();
result = l2.containsAll(l1);
System.out.println("Running Time: " + (System.currentTimeMillis() - startTime)/1000 + " seconds");
return result;
}
}