JProfiler Get rid of your performance problems and memory leaks! Modern Garbage Collection Tuning Java Performance Training Courses COURSES AVAILABLE NOW. We can provide training courses to handle all your Java performance needs Java Performance Tuning, 2nd ed The classic and most comprehensive book on tuning Java Java Performance Tuning Newsletter Your source of Java performance news. Subscribe now! Enter email: Training online Threading Essentials course JProfiler Get rid of your performance problems and memory leaks!

Published May 2003

TABLE OF CONTENTS

1. Introduction
2. How it Works
3. Installing IronEye SQL
4. How to Use IronEye SQL
5. Customizing Filters
6. Query Optimization
7. Suggested Optimizations
8. Conclusion
9. Obtaining a Free Trial Version
10. About IronGrid

Introduction

In typical application development, one of the most constrained resources (and causes of "slowness") is database access.? In general, sending requests over the wire (network I/O) and getting data from persistent storage (reading and writing to the database) are the two places that can cause performance deficiencies orders of magnitude greater than using a bubble sort instead of a quick sort.

IronEye SQL is a new tool from IronGrid that helps developers uncover some of the most bedeviling JDBC performance problems?slow queries, degrading performance, and beans that thrash the database?by providing an elegant way to intercept and time every interaction between an application (or application server) and a database.?? Using a JDBC driver wrapper, IronEye SQL provides Swing-based charts and graphs to analyze the performance of each SQL query.? It works with any JDBC compatible database, intercepts every database call, and requires no changes to source code.

How it Works

IronEye SQL provides a JDBC driver wrapper that a developer substitutes for the application?s native driver.? The wrapper intercepts all SQL being passed between an application (or application server) and a database.? Using a Java Swing-based GUI (similar to JMeter), developers can sort or filter SQL statements by various criteria.? Unlike other JDBC profiling tools, IronEye SQL does not require the installation and maintenance of its own separate application server.? Each developer in the organization can independently install and use the IronEye SQL GUI on his own machine without affecting the rest of the organization.

Also, because IronEye SQL relies on a vendor-neutral SQL wrapper, it can be used on Oracle, Sybase, Microsoft SQL Server, MySQL, Foxpro?and any other database for which a JDBC wrapper is available.

Installing IronEye SQL

Installation simply involves swapping the current JDBC driver for the driver wrapper, and then configuring the wrapper to use your original driver.? Start-to-finish, installation should take about 15 minutes.

The first step is to download the 30-day free trial software from http://www.irongrid.com/ironeyesql.? The basic steps to set up the program are:

1. Run the installer program, ironeyesql-install-1.0.nnn.exe.? The installer will prompt you for an installation directory.
   
   
2. When installation completes, the IronEye SQL application automatically starts and prompts you to configure your JDBC driver.
   
   In the Configuration dialog, enter the hostname of the machine on which the JDBC driver wrapper will be running.? If the application is running on your local machine, enter ?localhost?.
   
   Next, select the Port the driver will use to communicate with the GUI.? Port 3000 is configured by default, so you may need to change the setting if another application is already using that port.
   
   Finally, leave the Refresh Interval setting at 5000, unless you would like the GUI to poll the wrapper driver more frequently (set it lower to poll more frequently).
   
   
3. Go to the IronEye SQL installation directory that you specified in Step 1.? The top-level directory (e.g. C:\Program Files\IronGrid\IronEyeSql), contains three files:
   
   ironeyesql.jar
   p6spy.jar
   spy.properties
   
   Copy these files into your application (or application server?s) classpath.?
   
   Since each app server is different, customized instructions are available at: http://www.irongrid.com/documentation/ for numerous application servers (e.g. Weblogic, JBoss, Tomcat, Websphere, Resin, and others).
   
   
4. Edit your application?s current JDBC configuration and point the driver to:
   
   com.p6spy.engine.spy.P6SpyDriver
   
   
5. Open to the directory to which you copied the spy.properties file.? Edit the spy.properties file and point it to your original JDBC driver (this example assumes it is Oracle):
   
   realdriver = oracle.jdbc.driver.OracleDriver
   
   Also in the spy.properties file, configure the port number that will be used to share the profiling data with the GUI (this should be the same port number you selected in Step 2, port 3000).
   
   monitorport=3000
   
   
6. You configuration is now complete.? You can start your application server or database application and IronEye SQL will automatically intercept and analyze your SQL data.
   
   
7. Return to the IronEye SQL application and click the Connect button.? If IronEye SQL is not currently running, click Start -> Programs -> IronEyeSql -> IronEyeSql.

You can Connect and Disconnect to your application?s profiling data by clicking ?Connect? and ?Disconnect.?? Whenever your application sends a SQL query to the database, IronEye SQL will register a line in the console for each query.

How to Use IronEye SQL

As your application runs, each database query sent to the JDBC layer will appear in IronEye SQL?s interface.?

The application allows you to sort queries based on:

a) the number of times the query was called,

b) the query?s average total time,

c) the query?s maximum time

Clicking on an individual query displays more detailed performance data in the bottom of the console via three graphs, which include: Rows Returned, Time Performance, and Count.?

• Rows Returned displays the maximum, average, and minimum rows returned that match the selected SQL statement.? The same query can return different numbers of rows depending on the state of the data at the moment the query executed or the parameters passed in a PreparedStatement.
  
  
• Time Performance displays the maximum, average, and minimum completion times for the selected SQL statement.?
  
  
• Count displays the number of times the selected SQL statement has run since the server was started (or last purged).?

In addition to reporting the overall time for each query, IronEye SQL also reports Preparation time, Execution time, and Retrieval time for each query.

• Preparation time is the amount of time between when a statement is created and when it is executed.? In other words, it is the time between when you call?
  
  Statement stmt = conn.createStatement();
  String strSql = ?SELECT * from properties WHERE property_units > 4?;
  
  ?and when you call?
  
  ResultSet res = stmt.executeQuery(strSql);

• Execution time is the amount of time that the executeQuery() or executeUpdate() methods require to finish.
  
  
• Retrieval time is the total time spent in the ResultSet.next() method.? Since the .next() method is often called for each row retrieved, as the number of rows (or amount of data) increases, retrieval time also increases.

Customizing Filters

Because IronEye SQL captures every query sent by an application, the interface provides filtering capabilities.? Filtering will help you focus on key tables or the most problematic queries, suppressing those that are within expected performance boundaries.

For example, to filter the queries so that only those queries that average more than one (1) second, enter ?1000? in the left-most Average Time field, and click Apply Filter (not pictured).

Or, to filter queries so that only those queries that have never executed in anything less than one (1) second are displayed, enter ?1000? in the left-most Min Time field, and click Apply Filter (pictured below).

To filter only certain queries, enter the entire query in the SQL field, and click Apply Filter (not pictured).

Query Optimization

The data IronEye SQL produces helps developers discover and test optimizations.? Instead of putting blind trust in a black box optimization engine or a monolithic suite of third-party software, IronEye SQL gives developers control over the optimizations that are appropriate for their application.? This approach focuses on addressing the root cause of performance problems and the least expensive, most reliable solution?better code.

Suggested Optimizations

Armed with information from IronEye SQL, developers can return to their code to focus on improving the queries that harm database performance the most.? Following is a list of improvements based on the types of problems that IronEye SQL commonly uncovers:

• High preparation time.? Queries that require high preparation time may perform unnecessary activities in the time between when a statement is initialized and when it is executed.? Consider moving any code related to building the SQL query before creating the Statement object.
  
  
• Frequent queries.? Queries that are called frequently should be considered as candidates for data caching.? Simple caching strategies involve copying the RecordSet values into a Collection or using the CacheRowSet API described in this article at JavaWorld: http://www.javaworld.com/javaworld/jw-02-2001/jw-0202-cachedrow_p.html.
  
  Repeat queries of the same basic form should be considered for conversion to a PreparedStatement.? Java?s PreparedStatement object gives the database an opportunity to pre-parse the query, which can be especially time-saving when a query is repeatedly called.
  
  Consider consolidating multiple queries of the same table into a single statement.? For example, one developer found that his application was querying the database to retrieve a list of all ID?s from a table, then looping through the list to instantiate a bean for each ID.? The problem was that each bean instantiation, in turn, required a separate query to the database.? By changing the bean?s constructor to allow for an alternative instantiation, he was able to consolidate thousands of queries into a single query, reducing the execution time from over 75 seconds to under 20 seconds.
  
  
• High execution time.? Time spent in the executeQuery() or executeUpdate() methods is time that the database is spending to process and execute the query.? As a result, performance optimization can be approached from two directions?from the application side and the database side.
  
  In the application, developers can attempt to simplify queries to make them easier for the database to interpret.? If the query is repeatedly called, converting the query to a PreparedStatement would lower the cost of repeat query parsing.? Queries should also be examined to consider if they can be rewritten to avoid complex joins, or if the table design should be re-analyzed to improve performance.? Another execution bottleneck may be database-layer scripts such as triggers and stored procedures.? Strictly speaking, executing a script in the database layer is suboptimal for two reasons: 1) it requires CPU cycles on the most constricted resource, and 2) script execution is not the strength of the database.? Run the programmatic code on the application layer rather than the database, because compiled code will generally be faster and does not take cycles away from the bottleneck resource.? Alternatively, consider rewriting the SQL or database script to improve its execution time, for example, by using a compound or nested statement instead of an iterative statement.
  
  In the database, work with the DBA to investigate improvements to the database configuration such as adding indexes, increasing the SQL parsing cache, optimizing disk I/O by separating database tables from logs, and implementing database-specific hinting mechanisms (e.g. Oracle?s /* */ syntax) and idioms that improve the database?s query execution plan.
  
  
• High retrieval time.? Retrieval time includes all of the time spent returning records from the database to the application.? The primary drivers of this time are the number of rows returned, and the amount of data in each row.? Queries should be examined for opportunities to limit the number of columns or rows (or both) returned.? If the database stores large BLOB?s in a table (such as employee photos), returning the entire table via a ?SELECT *? statement may transfer an unnecessarily large amount of data across the network.? Consider returning fewer records, fewer columns, or both.??? Also, developers should consider whether all of the rows are needed at once, or if paging can be used to download only the data needed for the current step in execution.

Conclusion

Database performance problems can be the hidden killer in overall application performance.? With complex applications, encapsulation, and automated O/R mapping frameworks, database performance problems can go unnoticed until the worst possible time?just as an application?s usage begins to rise.? IronEye SQL equips developers with the tools to analyze query performance early, and fix performance problems at their root.

By operating as a JDBC wrapper, IronEye SQL requires no code changes.? Analytical data is presented via a Java Swing interface, avoiding the need to install, set up, and maintain a separate application server specific to performance tuning.? Morever, IronEye SQL does not require changes to production systems or architecture.?

IronEye SQL is an inexpensive tool (priced at $195 through 5/31/2003 and $395 thereafter) that you can install and configure in under 15-minutes, requires no code changes, and provides instant insight into one of the most insidious sources of performance problems.

Obtaining a free trial version

To obtain a free 30-day trial version of IronEye SQL, download a copy from ?http://www.irongrid.com/ironeyesql.? Download IronEye SQL before May 31, 2003 and you will automatically be entered in a contest for $2,500 in cash (please see http://www.irongrid.com/catalog/promotion_home.php for complete contest details).

About IronGrid

IronGrid, Inc. provides lightweight Java development tools that solve specific problems and provide immediate results to Java application developers.? Products are affordably priced for wide usage, can be installed quickly, and require no changes to a developer?s source code.? IronGrid focuses on products that enable software performance turning throughout the development cycle, to help developers deliver software that is on time, on budget, and on spec.? The tools support a practice called continuous performance. ?Like continuous integration, continuous performance is an extreme programming extension that favors performance testing throughout the entire lifecycle of an application. IronGrid is venture-backed and headquartered in Austin, Texas.