Vinay's Blog: Tips and Tricks

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Dec 3, 2009

Performance Optimization for large I/O Operations

PDF, performance tuning, Tips and TricksNo comments

This article discussed about the following topics

Issues with export & import of huge files
Our Approaches to resolve these issues
NIO package advantage
Performance issues during serialization
Progressive rendering
Case Studies with Solutions

Issues while exporting huge files

Issues faced during exporting or importing of large Data/Files:

It takes long time to export or import a huge data/file.
Out of Memory error during the file I/O operation or copying to a location.
In some instances the application hangs. Hard disks are very good at reading and writing sizable chunks of data, but they are much less efficient when working with small blocks of data.
Transaction timeouts.

Our Approach-Key points

The basic rules for speeding up I/O performance are

To maximize I/O performance, you should batch read and write operations.
Use Buffered stream operation to achieve batch read and write operations or use Java NIO package.
Minimize accessing the hard disk.
Minimize processing bytes and characters individually.
Minimize accessing the underlying operating system.
Better understanding of java.io and nio package package can lead to major improvements in I/O performance.

Let us look at some of the techniques to improve I/O performance

Large chunks of a file are read from a disk and then accessed a byte or character at a time. This is a problem.
Use buffering to minimize disk access and underlying operating system. As shown below, with buffering

Without buffering : inefficient code

try
{
    File f = new File("myFile.txt");
    FileInputStream fis = new FileInputStream(f);
    int count = 0;
    int b = ;
    while((b = fis.read()) != -1)
    {
        if(b== '\n')
        {
            count++;
        }
    }
    // fis should be closed in a finally block.
    fis.close() ;
}
catch(IOException io)
{
}

Note : fis.read() is a native method call to theunderlying system.

With Buffering: yields better performance

try
{
    File f = new File("myFile.txt");
    FileInputStream fis = new FileInputStream(f);
    BufferedInputStream bis = new BufferedInputStream(fis);
    int count = 0;
    int b = ;
    while((b = bis.read()) != -1)
    {
        if(b== '\n')
        {
            count++;
        }
    }
    //bis should be closed in a finally block.
    bis.close() ;
}
catch(IOException io)
{
}

Note: bis.read() takes the next byte from the input buffer and only rarely access the underlying operating system.

Instead of reading a character or a byte at a time, the above code with buffering can be improved further by reading one line at a time as shown below:

FileReader fr = new FileReader(f); 
BufferedReader br = new BufferedReader(fr); 
While (br.readLine() != null) count++;

It is recommended to use logging frameworks like Log4J or apache commons logging, which uses buffering instead of using default behavior of System.out.println(…..) for better performance.

Use the NIO package

If you are using JDK 1.4 or later use the NIO package, which uses performance-enhancing features like buffers to hold data, memory mapping of files, non-blocking I/O operations etc.

Previously Java IO code must read data from the file system, bring it up into JVM memory, and then push it back down to the file system through Java IO.

Java NIO has the potential to really improve performance in a lot of areas. File copies is just one of them

Provides the ability to monitor multiple I/O operations concurrently, also known as "multiplexing."

Multiplexed NIO is a technique that moves all the I/O work into a single thread that watches over many I/O operations executing concurrently.

NIO-Example

Basic file-to-file copy algorithm implemented using 'NIO':

public static void copyFile(File sourceFile, File destFile) throws IOException
{
    if(!destFile.exists())
    {
        destFile.createNewFile();
    }
      FileChannel source = null;
    FileChannel destination = null;
    try
    {
        source = new FileInputStream(sourceFile).getChannel();
        destination = new FileOutputStream(destFile).getChannel();
        destination.transferFrom(source, 0, source.size());
    }
    finally
    {
        if(source != null)
        {
            source.close();
        }
        if(destination != null)
        {
            destination.close();
        }
    }
}

Use the NIO package

Note that there is no reference to the buffering used or the implementation of the actual copy algorithm.

This is key to the potential performance advantages of this algorithm.

Serialization Example

Serializing a class and writing to an Output stream.

This stems from the fact that serialization is a recursive process.

If your class has Jpanel then all of the Swing UI widgets and any objects they reference in a class are written. This is one care item to be taken care during Serialization.

To improved Serialization we need to take care when object are serialized.

Use the transient keyword to specify when the object implements Serialization.

public class TestObject implements Serializable
{
    private int value;
    private String name;
    private Date timeStamp;
    private JPanel panel;
    public TestObject(int value)
    {
        this.value = value;
        name = new String("Object:" + value);
        timeStamp = new Date();
        panel = new JPanel();
        panel.add(new JTextField());
        panel.add(new JButton("Help"));
        panel.add(new JLabel("This is a text label"));
    }
}
//Writing objects to a stream:
for (int i =0;i &lt;50; i++)
{
    vector.addElement(new TestObject(i));
}
Stopwatch timer = new Stopwatch().start();
try
{
    OutputStream file = new FileOutputStream("Out.test");
    OutputStream buffer = new BufferedOutputStream(file);
    ObjectOutputStream out = new ObjectOutputStream(buffer);
    out.writeObject(vector);
    out.close();
}
catch (Exception e)
{
    e.printStackTrace();
}
timer.stop();
System.out.println("elapsed = " + timer.getElapsedTime());
//Reading Objects From the Stream:
Stopwatch timer = new Stopwatch().start();
try
{
    InputStream file = new FileInputStream("Out.test");
    InputStream buffer = new BufferedInputStream(file);
    ObjectInputStream in = new ObjectInputStream(buffer);
    vector = (Vector)in.readObject();
    in.close();
}
catch (Exception e)
{
    e.printStackTrace();
}
timer.stop();
System.out.println("elapsed = " + timer.getElapsedTime());
//Improved serializable object
public class TestObjectTrans implements Serializable
{
    private int value;
    private transient String name;
    private Date        timeStamp;
    private transient JPanel panel;
    public TestObjectTrans(int value)
    {
        this.value = value;
        timeStamp = new Date();
        initTransients();
    }
    public void initTransients()
    {
        name = new String("Object:" + value);
        panel = new JPanel();
        panel.add(new JTextField());
        panel.add(new JButton("Help"));
        panel.add(new JLabel("This is a text label"));
    }
    private void readObject(ObjectInputStream in)
    throws IOException, ClassNotFoundException
    {
        in.defaultReadObject();
        initTransients();
    }
}

Case Study 1

Requirement :

Export the data to an export sheet when export data link is clicked.

Data is retrieved from a table which has 65 columns and more than 80,000 records.

Solution:

To achieve the above requirement read the records using readLine() and store it in a String Buffer and write to an Output Stream using NIO.

Keep a counter and which will count the number of records.

The string Buffer length to be set to 0 and clear the memory and flush the output stream when counter count reaches 20.

Clearing will have the advantage of not storing the huge data in memory and write the data quickly to the outputstream.

Case Study 2

Requirement:

Read a CSV file of 50MB and insert the data into a DB based on few processing instructions.

Solution:

Read the file from the remote Location and copy to a local location using java NIO on the server for faster retrieval. This should be a temporary file.

Use readLine() of the file InputStream and process data is set of 50 by storing them in a String Buffer.

Use a batchupdate to store data in records of 50 it in the database.

Incase if there is an exception in process of updating the batch job then we will add the 50 records in an exception list & process them one by one separately.

The logger will contain the error log for records which were not updated with exception.

Case Study 3

Requirement:

User selects to generate a 500 pages PDF report on click of a link/submit of a page.

Solution:

Since the report size is too huge of 500 page. We will loading the whole page in background, but just show around first 10 to 20 pages on click or submit so that user UI is not hanged/idle till all the 500 pages.

As the user scroll down the PDF the remaining pages will be loaded parallel in background.

Progressive rendering is the act of displaying each object as it is downloaded.

A method and a system are provided for processing displayed text and progressively displaying results of processing the displayed text. In some embodiments, displayed text may be submitted as processing requests to process portions of the displayed text Both IE and FF supports progressive rendering;

They differ on how they render tables.

Internet Explorer renders a , it downloads all the objects within the table before displaying it. This is required so that Internet Explorer can render the table with the correct width for each column.

Firefox renders all objects progressively regardless if it's in a table. That is to say - each object is displayed as soon as it is downloaded.

If a html page has to display a table with more than 1000 records then make an Ajax call and load the data progressively for a set of 50 records.

Performance Optimization for large I/O Operations

PDF, performance tuning, Tips and TricksNo comments

This article discussed about the following topics

Issues with export & import of huge files
Our Approaches to resolve these issues
NIO package advantage
Performance issues during serialization
Progressive rendering
Case Studies with Solutions

Issues while exporting huge files

Issues faced during exporting or importing of large Data/Files:

It takes long time to export or import a huge data/file.
Out of Memory error during the file I/O operation or copying to a location.
In some instances the application hangs. Hard disks are very good at reading and writing sizable chunks of data, but they are much less efficient when working with small blocks of data.
Transaction timeouts.

Our Approach-Key points

The basic rules for speeding up I/O performance are

To maximize I/O performance, you should batch read and write operations.
Use Buffered stream operation to achieve batch read and write operations or use Java NIO package.
Minimize accessing the hard disk.
Minimize processing bytes and characters individually.
Minimize accessing the underlying operating system.
Better understanding of java.io and nio package package can lead to major improvements in I/O performance.

Let us look at some of the techniques to improve I/O performance

Large chunks of a file are read from a disk and then accessed a byte or character at a time. This is a problem.
Use buffering to minimize disk access and underlying operating system. As shown below, with buffering

Without buffering : inefficient code

try
{
    File f = new File("myFile.txt");
    FileInputStream fis = new FileInputStream(f);
    int count = 0;
    int b = ;
    while((b = fis.read()) != -1)
    {
        if(b== '\n')
        {
            count++;
        }
    }
    // fis should be closed in a finally block.
    fis.close() ;
}
catch(IOException io)
{
}

Note : fis.read() is a native method call to theunderlying system.

With Buffering: yields better performance

try
{
    File f = new File("myFile.txt");
    FileInputStream fis = new FileInputStream(f);
    BufferedInputStream bis = new BufferedInputStream(fis);
    int count = 0;
    int b = ;
    while((b = bis.read()) != -1)
    {
        if(b== '\n')
        {
            count++;
        }
    }
    //bis should be closed in a finally block.
    bis.close() ;
}
catch(IOException io)
{
}

Note: bis.read() takes the next byte from the input buffer and only rarely access the underlying operating system.

Instead of reading a character or a byte at a time, the above code with buffering can be improved further by reading one line at a time as shown below:

FileReader fr = new FileReader(f); 
BufferedReader br = new BufferedReader(fr); 
While (br.readLine() != null) count++;

It is recommended to use logging frameworks like Log4J or apache commons logging, which uses buffering instead of using default behavior of System.out.println(…..) for better performance.

Use the NIO package

If you are using JDK 1.4 or later use the NIO package, which uses performance-enhancing features like buffers to hold data, memory mapping of files, non-blocking I/O operations etc.

Previously Java IO code must read data from the file system, bring it up into JVM memory, and then push it back down to the file system through Java IO.

Java NIO has the potential to really improve performance in a lot of areas. File copies is just one of them

Provides the ability to monitor multiple I/O operations concurrently, also known as "multiplexing."

Multiplexed NIO is a technique that moves all the I/O work into a single thread that watches over many I/O operations executing concurrently.

NIO-Example

Basic file-to-file copy algorithm implemented using 'NIO':

public static void copyFile(File sourceFile, File destFile) throws IOException
{
    if(!destFile.exists())
    {
        destFile.createNewFile();
    }
      FileChannel source = null;
    FileChannel destination = null;
    try
    {
        source = new FileInputStream(sourceFile).getChannel();
        destination = new FileOutputStream(destFile).getChannel();
        destination.transferFrom(source, 0, source.size());
    }
    finally
    {
        if(source != null)
        {
            source.close();
        }
        if(destination != null)
        {
            destination.close();
        }
    }
}

Use the NIO package

Note that there is no reference to the buffering used or the implementation of the actual copy algorithm.

This is key to the potential performance advantages of this algorithm.

Serialization Example

Serializing a class and writing to an Output stream.

This stems from the fact that serialization is a recursive process.

If your class has Jpanel then all of the Swing UI widgets and any objects they reference in a class are written. This is one care item to be taken care during Serialization.

To improved Serialization we need to take care when object are serialized.

Use the transient keyword to specify when the object implements Serialization.

public class TestObject implements Serializable
{
    private int value;
    private String name;
    private Date timeStamp;
    private JPanel panel;
    public TestObject(int value)
    {
        this.value = value;
        name = new String("Object:" + value);
        timeStamp = new Date();
        panel = new JPanel();
        panel.add(new JTextField());
        panel.add(new JButton("Help"));
        panel.add(new JLabel("This is a text label"));
    }
}
//Writing objects to a stream:
for (int i =0;i &lt;50; i++)
{
    vector.addElement(new TestObject(i));
}
Stopwatch timer = new Stopwatch().start();
try
{
    OutputStream file = new FileOutputStream("Out.test");
    OutputStream buffer = new BufferedOutputStream(file);
    ObjectOutputStream out = new ObjectOutputStream(buffer);
    out.writeObject(vector);
    out.close();
}
catch (Exception e)
{
    e.printStackTrace();
}
timer.stop();
System.out.println("elapsed = " + timer.getElapsedTime());
//Reading Objects From the Stream:
Stopwatch timer = new Stopwatch().start();
try
{
    InputStream file = new FileInputStream("Out.test");
    InputStream buffer = new BufferedInputStream(file);
    ObjectInputStream in = new ObjectInputStream(buffer);
    vector = (Vector)in.readObject();
    in.close();
}
catch (Exception e)
{
    e.printStackTrace();
}
timer.stop();
System.out.println("elapsed = " + timer.getElapsedTime());
//Improved serializable object
public class TestObjectTrans implements Serializable
{
    private int value;
    private transient String name;
    private Date        timeStamp;
    private transient JPanel panel;
    public TestObjectTrans(int value)
    {
        this.value = value;
        timeStamp = new Date();
        initTransients();
    }
    public void initTransients()
    {
        name = new String("Object:" + value);
        panel = new JPanel();
        panel.add(new JTextField());
        panel.add(new JButton("Help"));
        panel.add(new JLabel("This is a text label"));
    }
    private void readObject(ObjectInputStream in)
    throws IOException, ClassNotFoundException
    {
        in.defaultReadObject();
        initTransients();
    }
}

Case Study 1

Requirement :

Export the data to an export sheet when export data link is clicked.

Data is retrieved from a table which has 65 columns and more than 80,000 records.

Solution:

To achieve the above requirement read the records using readLine() and store it in a String Buffer and write to an Output Stream using NIO.

Keep a counter and which will count the number of records.

The string Buffer length to be set to 0 and clear the memory and flush the output stream when counter count reaches 20.

Clearing will have the advantage of not storing the huge data in memory and write the data quickly to the outputstream.

Case Study 2

Requirement:

Read a CSV file of 50MB and insert the data into a DB based on few processing instructions.

Solution:

Read the file from the remote Location and copy to a local location using java NIO on the server for faster retrieval. This should be a temporary file.

Use readLine() of the file InputStream and process data is set of 50 by storing them in a String Buffer.

Use a batchupdate to store data in records of 50 it in the database.

Incase if there is an exception in process of updating the batch job then we will add the 50 records in an exception list & process them one by one separately.

The logger will contain the error log for records which were not updated with exception.

Case Study 3

Requirement:

User selects to generate a 500 pages PDF report on click of a link/submit of a page.

Solution:

Since the report size is too huge of 500 page. We will loading the whole page in background, but just show around first 10 to 20 pages on click or submit so that user UI is not hanged/idle till all the 500 pages.

As the user scroll down the PDF the remaining pages will be loaded parallel in background.

Progressive rendering is the act of displaying each object as it is downloaded.

A method and a system are provided for processing displayed text and progressively displaying results of processing the displayed text. In some embodiments, displayed text may be submitted as processing requests to process portions of the displayed text Both IE and FF supports progressive rendering;

They differ on how they render tables.

Internet Explorer renders a , it downloads all the objects within the table before displaying it. This is required so that Internet Explorer can render the table with the correct width for each column.

Firefox renders all objects progressively regardless if it's in a table. That is to say - each object is displayed as soon as it is downloaded.

If a html page has to display a table with more than 1000 records then make an Ajax call and load the data progressively for a set of 50 records.

Tips & Tricks for SQUID (Proxy) Server

Tips and TricksNo comments

Overview

This article will be helpful to improve your squid performance in any hectic and slow bandwidth / traffic kind of scenario. This will also helpful to the organization, who will use the only one Squid Server Hardware and giving the internet access to more then 1000 users. Even, you can bypass or stream line your SSL / SAFE ports for any outgoing traffic, which needs to be allow.

1) Faster Performance of Cache

To take the advantage of the Squid Cache, mount the “Cache directory” on “diskd” format. Also use more than 1 hard disk and mount /cache directory on each hard disk to get faster performance of cache.

2) Partition & Mount Point

Create and Mount the /log and /var directory on separate hard disk to faster performance of Squid Server.

3) Bandwidth Management

If you have Lower Bandwidth and Higher End Server with minimum 3 harddisk for Cache and 4 GB Minimum Ram, then keep:

“maximum_object_size 4028 KB” &
“maximum_object_size_in_memory 3072 KB”
And, If you have Higher Bandwidth and Lowered Server, then keep:
“maximum_object_size 1024 KB” &
“maximum_object_size_in_memory 512 KB”

4) Only 1 Authentication

To set the one user can access the internet from one system only on same time, add the below line to your squid.conf file.

acl only1 max_user_ip -s 1
http_access deny only1

5) Squid File Modify

When ever you need to change your squid.conf file, save it and write the command as below to take the change effect immediately:

squid –k reconf

6) Cache Initialization

If and problem persist regarding to initializing the squid cache, give the write permission to the specified directory. (i.e. chmod 777 /cache)

7) Use Maximum Memory for Squid

If you have more than sufficient memory in your squid server, set the below lines in your squid.conf file, to get the highest performance of your unused memory.

memory_pools on
memory_pools_limit 2048 MB

If you set the value of memory_pools_limit to 0, squid will keep all memory it can.

8) Retry while Error

If set “retry_on_error on”, squid will automatically retry requests when receiving an error response. This is mainly useful if you are in a complex cache hierarchy to work around access control errors.

9) Memory Warning

If you set this to “high_memory_warning 2048 MB”, and the memory usage will be exceeds to determined value, Squid prints a WARNING with debug level 0 to get the administrators attention.

10) Bypass the SSL ports

To bypass the SSL ports from squid server, mentioned the acl as below:

acl SSL_ports port 443
http_access deny CONNECT !SSL_ports

Tips & Tricks for SQUID (Proxy) Server

Tips and TricksNo comments

Overview

1) Faster Performance of Cache

2) Partition & Mount Point

Create and Mount the /log and /var directory on separate hard disk to faster performance of Squid Server.

3) Bandwidth Management

If you have Lower Bandwidth and Higher End Server with minimum 3 harddisk for Cache and 4 GB Minimum Ram, then keep:

“maximum_object_size 4028 KB” &
“maximum_object_size_in_memory 3072 KB”
And, If you have Higher Bandwidth and Lowered Server, then keep:
“maximum_object_size 1024 KB” &
“maximum_object_size_in_memory 512 KB”

4) Only 1 Authentication

To set the one user can access the internet from one system only on same time, add the below line to your squid.conf file.

acl only1 max_user_ip -s 1
http_access deny only1

5) Squid File Modify

When ever you need to change your squid.conf file, save it and write the command as below to take the change effect immediately:

squid –k reconf

6) Cache Initialization

If and problem persist regarding to initializing the squid cache, give the write permission to the specified directory. (i.e. chmod 777 /cache)

7) Use Maximum Memory for Squid

If you have more than sufficient memory in your squid server, set the below lines in your squid.conf file, to get the highest performance of your unused memory.

memory_pools on
memory_pools_limit 2048 MB

If you set the value of memory_pools_limit to 0, squid will keep all memory it can.

8) Retry while Error

9) Memory Warning

To bypass the SSL ports from squid server, mentioned the acl as below:

acl SSL_ports port 443
http_access deny CONNECT !SSL_ports

Top 10 Blackberry Troubleshooting Tips

mobile, Tips and TricksNo comments

Introduction

Use this article to resolve a problem involving or relating to the BlackBerry wireless device, before engaging the help of your BlackBerry technical support provider.

Troubleshooting Tips

Tip 1

Check the signal strength. Sufficient signal strength allows the BlackBerry device to send and receive wireless information.

Turn on the device.
On the device Home screen, click Options and select Status.
In the Signal field, verify the value is less than 100 dBm.

Note: For BlackBerry devices, verify GPRS, or EDGE network status indicators appear in the status section on the Home screen.

Tip 2

Reset the device.

Tip 3

Check network settings. Appropriate network settings enable the device to send and receive information on the wireless network.

For BlackBerry wireless devices based on Java

On the device Home screen, click Options and select Network.
Click Scan for Networks and verify the device is running on the correct network.

For RIM Wireless Handhelds based on C++

On the RIM handheld, click Options and select Network Settings.
In the Radio field, verify the value is set to On.
Verify the appropriate country is set for Roaming.
Verify the status is active.
Click the trackwheel and select Register Now.
Verify the handheld registration request has been sent

Tip 4

Verify the device-to-computer connection to confirm that the device connects properly to the personal computer.

Verify the device is properly connected to the personal computer.
Close and open BlackBerry Desktop Manager.
Verify the device is detected.

Tip 5

Synchronize the device with the BlackBerry Desktop Software in order to verify that the information is current.

Connect the device to the personal computer.
In Desktop Manager, open Intellisync.
Click Configure PIM and select the application check box you want to synchronize.
Click OK.
Verify the Synchronize PIM option is selected.
Click Synchronize Now.

Tip 6

Send a test message from the mail client to the device. If you receive the message in your device Inbox, this proves your messaging and collaboration server is able to process internal messaging.

Tip 7

Send a message and personal identification number (PIN) message from the device. This confirms that you can send messages from the device to the mail client or to other recipients with a BlackBerry device.

Tip 8

Verify messages are redirected to the device based on the following message redirection method:

BlackBerry Enterprise Server - Check with your BlackBerry Enterprise Server administrator to verify the BlackBerry Enterprise Server is working as expected.
BlackBerry Desktop Redirector - Confirm the BlackBerry Desktop Redirector is running on the personal computer and displays a Running status.
BlackBerry Internet Service - Contact your service provider to verify the account is provisioned properly.

Tip 9

Run the BlackBerry Application Loader in order to verify that your applications are loaded correctly.

Warning: Back up the device data with the Backup and Restore application before your

complete the following steps.

Connect the device to the personal computer.
In Desktop Manager, open Application Loader.
Click Next and follow the on-screen instructions

Tip 10

For specific issues and troubleshooting tips, search the Support Knowledge Base.

Conclusion

If you are still experiencing issues after troubleshooting, Consult the BlackBerry Technical Support (Incase of India it is with Airtel-9871427070)

Top 10 Blackberry Troubleshooting Tips

mobile, Tips and TricksNo comments

Introduction

Use this article to resolve a problem involving or relating to the BlackBerry wireless device, before engaging the help of your BlackBerry technical support provider.

Troubleshooting Tips

Tip 1

Check the signal strength. Sufficient signal strength allows the BlackBerry device to send and receive wireless information.

Turn on the device.
On the device Home screen, click Options and select Status.
In the Signal field, verify the value is less than 100 dBm.

Note: For BlackBerry devices, verify GPRS, or EDGE network status indicators appear in the status section on the Home screen.

Tip 2

Reset the device.

Tip 3

Check network settings. Appropriate network settings enable the device to send and receive information on the wireless network.

For BlackBerry wireless devices based on Java

On the device Home screen, click Options and select Network.
Click Scan for Networks and verify the device is running on the correct network.

For RIM Wireless Handhelds based on C++

On the RIM handheld, click Options and select Network Settings.
In the Radio field, verify the value is set to On.
Verify the appropriate country is set for Roaming.
Verify the status is active.
Click the trackwheel and select Register Now.
Verify the handheld registration request has been sent

Tip 4

Verify the device-to-computer connection to confirm that the device connects properly to the personal computer.

Verify the device is properly connected to the personal computer.
Close and open BlackBerry Desktop Manager.
Verify the device is detected.

Tip 5

Synchronize the device with the BlackBerry Desktop Software in order to verify that the information is current.

Connect the device to the personal computer.
In Desktop Manager, open Intellisync.
Click Configure PIM and select the application check box you want to synchronize.
Click OK.
Verify the Synchronize PIM option is selected.
Click Synchronize Now.

Tip 6

Send a test message from the mail client to the device. If you receive the message in your device Inbox, this proves your messaging and collaboration server is able to process internal messaging.

Tip 7

Tip 8

Verify messages are redirected to the device based on the following message redirection method:

BlackBerry Enterprise Server - Check with your BlackBerry Enterprise Server administrator to verify the BlackBerry Enterprise Server is working as expected.
BlackBerry Desktop Redirector - Confirm the BlackBerry Desktop Redirector is running on the personal computer and displays a Running status.
BlackBerry Internet Service - Contact your service provider to verify the account is provisioned properly.

Tip 9

Run the BlackBerry Application Loader in order to verify that your applications are loaded correctly.

Warning: Back up the device data with the Backup and Restore application before your

complete the following steps.

Connect the device to the personal computer.
In Desktop Manager, open Application Loader.
Click Next and follow the on-screen instructions

Tip 10

For specific issues and troubleshooting tips, search the Support Knowledge Base.

Conclusion

If you are still experiencing issues after troubleshooting, Consult the BlackBerry Technical Support (Incase of India it is with Airtel-9871427070)

DB2 Tuning Tips

Tips and TricksNo comments

1) Take out any / all-Scalar functions coded on columns in predicates. For example, this is the most common:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE YEAR(HIREDATE) = 2005

Should be coded as:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE HIREDATE BETWEEN ‘2005-01-01’ and ‘2005-12-31’

2) Take out any / all mathematics coded on columns in predicates. For example:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE SALARY * 1.1 > 50000.00

Should be coded as:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE SALARY > 50000.00 / 1.1

3) Stay away from ‘Distinct’ if at all possible.

If duplicates are to be eliminated from the result set, try:

- ‘Group By’ which looks to take advantage of any associated indexes to eliminate a sort for uniqueness.

- Rewriting the query using an ‘In’ or ‘Exists’ subquery.

This will work if the table causing the duplicates (due to a one to many relationship) does not have data being returned as part of the result set.

4) Minimize the SQL requests to DB2.

This is huge in performance tuning of programs, especially batch programs because they tend to process more data. Every time an SQL call is sent to the database manager, there is overhead in sending the SQL statement to DB2, going from one address space in the operating system to the DB2 address space for SQL execution.

In general, developers need to minimize:

- The number of time cursors are Opened/Closed

- The number of random SQL requests (noted as synchronized reads in DB2 monitors).

5) Give prominence to Stage 1 over Stage 2 Predicates.

Always try to code predicates as Stage 1 and index able. In general, Stage 2 predicates do not perform as well and consume extra CPU. See the IBM SQL Reference Guide to determine what predicates are Stage 1 vs. Stage 2 and make sure to go to the correct Version of DB2 when checking. Recommendation: Use Visual Explain.

IBM DB2 Manuals: Search on ==> Summary of Predicate Processing

6) Never put filtering logic within application code.

It is always best to have all the filtering logic that is needed written as predicates in a SQL statement. Do not leave some predicates out and have the database manager bring in extra rows and then eliminate / bypass some of the rows through program logic checks. (Some people call this Stage 3 processing)..

Deviate only when performance is an issue and not all other efforts have provided significant enough improvement in performance.

7) When using cursors, use ROWSET positioning and fetching using multi row fetch, multi row update, and multi row insert. New as of V8.

DB2 V8 introduced support for the manipulation of multiple rows on fetches, updates, and insert processing. Prior versions of DB2 would only allow for a program to process one row at a time during cursor processing. Now having the ability to fetch, update, or insert more than 1 row at a time reduces network traffic and other related costs associated with each call to DB2. The recommendation is to start with 100 row fetches, inserts, or updates, and then test other numbers. It has been proven many times that this process reduces runtime on average of 35%. Consult the IBM DB2 manuals for further detail and coding examples.

8) Take advantage of Scalar Full selects within the Select clause whenever possible. New as of V8:

Many times the output needed from SQL development requires a combination of Detail and aggregate data together. There are typically a number of ways to code this with SQL, but with the Scalar Full select now part of DB2 V8, there is now another option that is very efficient as long as indexes are being used.

For Example: Individual Employee Report with Aggregate Department Averages

SELECT E1.EMPNO, E1.LASTNAME, 

E1.WORKDEPT, E1.SALARY, (SELECT AVG(E2.SALARY)

FROM EMPLOYEE E2

WHERE E2.WORKDEPT = E1.WORKDEPT)

AS DEPT_AVG_SAL 

FROM EMPLOYEE E1

ORDER BY E1.WORKDEPT, E1.SALARY

9) Watch out for tablespace scans.

What do you do? If you as a developer see that a tablespace scan is occurring in your SQL execution, then go through the following checklist to help figure out why?

- The predicate(s) may be poorly coded in a non-indexable way.

- The predicates in the query do not match any available indexes on the table.

- The table could be small, and DB2 decides a tablespace scan may be faster than index processing.

- The catalog statistics say the table is small, or maybe there are no statistics on the table.

- The predicates are such that DB2 thinks the query is going to retrieve a large enough amount of data that would require a tablespace scan.

- The predicates are such that DB2 picks a non-clustered index, and the number of pages to retrieve is high enough based on total number of pages in the table to require a tablespace scan.

- The tablespace file or index files could physically be out of shape and need a REORG.

- The predicates in the query do not match any available indexes on the table

10) Only code the columns needed in the Select portion of the SQL statement.

Having extra columns can have an affect on:

- The optimizer choosing ‘Index Only’

- Expensiveness of any sorts

- Optimizer’s choice of join methods

DB2 Tuning Tips

Tips and TricksNo comments

1) Take out any / all-Scalar functions coded on columns in predicates. For example, this is the most common:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE YEAR(HIREDATE) = 2005

Should be coded as:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE HIREDATE BETWEEN ‘2005-01-01’ and ‘2005-12-31’

2) Take out any / all mathematics coded on columns in predicates. For example:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE SALARY * 1.1 > 50000.00

Should be coded as:

SELECT EMPNO, LASTNAME

FROM EMPLOYEE

WHERE SALARY > 50000.00 / 1.1

3) Stay away from ‘Distinct’ if at all possible.

If duplicates are to be eliminated from the result set, try:

- ‘Group By’ which looks to take advantage of any associated indexes to eliminate a sort for uniqueness.

- Rewriting the query using an ‘In’ or ‘Exists’ subquery.

This will work if the table causing the duplicates (due to a one to many relationship) does not have data being returned as part of the result set.

4) Minimize the SQL requests to DB2.

In general, developers need to minimize:

- The number of time cursors are Opened/Closed

- The number of random SQL requests (noted as synchronized reads in DB2 monitors).

5) Give prominence to Stage 1 over Stage 2 Predicates.

IBM DB2 Manuals: Search on ==> Summary of Predicate Processing

6) Never put filtering logic within application code.

Deviate only when performance is an issue and not all other efforts have provided significant enough improvement in performance.

7) When using cursors, use ROWSET positioning and fetching using multi row fetch, multi row update, and multi row insert. New as of V8.

8) Take advantage of Scalar Full selects within the Select clause whenever possible. New as of V8:

For Example: Individual Employee Report with Aggregate Department Averages

SELECT E1.EMPNO, E1.LASTNAME, 

E1.WORKDEPT, E1.SALARY, (SELECT AVG(E2.SALARY)

FROM EMPLOYEE E2

WHERE E2.WORKDEPT = E1.WORKDEPT)

AS DEPT_AVG_SAL 

FROM EMPLOYEE E1

ORDER BY E1.WORKDEPT, E1.SALARY