DB2 Performance Tuning

From archive: June 2011

DB2 Java Performance: DB2 Transaction Framework

DaveBeulke Tags: db2 java 2,131 Views

Given the object model of Java and the relational model of the DB2 database, accessing data properly continues to be difficult for most DB2 Java application developers. Over the history of DB2 Java development, there have been many attempts within vendor products, interfaces and open source projects to bridge this object to relational data chasm. Many object to relational mapping of (ORM) solutions exist but few applications leverage them properly or efficiently.

Java Architectures

The leading architectures providing good performance for my DB2 Java clients today, Enterprise Java Bean (EJB) specifications and Java Persistence Architecture (JPA) continue to evolve. Sometimes I have seen the open source Hibernate product implemented by DB2 Java projects looking for a quick database interface, but usually it is leveraged improperly and performs poorly. Sometimes the Hibernate interface even masks or creates problems in DB2 Java systems with its SQL handling and various parameter settings. Some clients have even written their own plain old Java object (POJO) interface to get to their DB2 data.

Any of these ways to get to the data can work and get good performance if the proper application framework, architecture and design pattern is matched with the correct application and transaction type. Working with IMS, IDMS, CICS and MQ systems referencing DB2 shows that very large databases with high availability have a variety of frameworks, architectures and design patterns. Just because an application is using an object oriented language such as Java, C## or .Net does not mean that performance or good database standards and principles should not be implemented or expected. Sometimes the application focuses on making the application fit the framework and more attention should be paid to DB2 Java performance.

DB2 Performance is Java Performance: Holy Grail (cont.)

DaveBeulke Tags: db2 java 1 Comment 2,597 Views

Over the last three years, my clients have shown that multiple framework, architecture and programming patterns are usually implemented within the same project. The problem is the poor performance lessons experienced from the application implementation are not fully understood and the performance problems are continued and replicated into the next architecture, framework or pattern iteration, including DB2 Java applications.

Each application is different and each service or process within the application is unique. Step back and be flexible in your design patterns to understand that one or two architectures, frameworks or programming patterns are not correct for every situation. Your design should reflect the application requirements and the correct implementation for achieving the best DB2 Java performance might mean a variety or mix of approaches.

Objects within Java are great for flexibility and reuse. Java services and open source products such as Hibernate, iBatis, Ruby and techniques such as Java Persistence Architecture (JPA) and Data Access Objects (DAO) are great for accessing the DB2 database. Many of these techniques are common in today’s DB2 Java applications. My clients have experienced problems with these techniques when the application processing does not pay attention to the transaction integrity or the unit of work properly. When this happens the DB2 Java application processes usually have connected to the database multiple times, processed the transaction too many times or not committed or rolled back the transaction properly. These DB2 Java transaction situations usually manifest themselves in JDBC errors or poor referential integrity issues that developers blame on the database. Unfortunately, it is not the database but the application coding of the services that cause the problems.

In the coming weeks I will talk further about DB2 Java applications, their processing and issues that I have experienced with my clients. I know it will help you avoid some of these problems too.

DB2 Performance is Java Performance: Holy Grail

DaveBeulke Tags: java db2 1 Comment 2,804 Views

When getting my taxes ready every year, I review the previous year’s activity. Reviewing 2008 showed that the majority of my consulting was spent fixing and tuning DB2 Java based systems. This is not a big surprise since the trend and majority of my clients since 2005 have had DB2 Java performance tuning opportunities. Even in 2011, the trend of Java applications being built and implemented with DB2 z/OS and LUW continues at an ever-growing pace.

In most of these client situations, the majority of the problem has not been the database or the DB2 LUW or z/OS system; it has been related to the DB2 Java application processing. Java is the new workhorse and many systems are being implemented and not performing well. Working with my clients, I’ve discovered a variety of issues with these systems and over the next several weeks I will highlight the most common factors that kill performance for these new DB2 Java application systems.

By leveraging the new object model and great application development tools in Eclipse, according to a E-week poll in February 2009, Java applications with AJAX and JavaScript development are taking over as the dominate application programming languages at the start of this century -- almost twice as fast as .Net applications.

Many object framework, architecture and programming pattern options are implemented with these languages. Given that there is no one object framework, architecture or application programming pattern that is right for every situation, there is neither a single right nor wrong way for performance success with your DB2 Java application.

(To be continued next week.)

DB2 10 SQL Optimization Preservation

DaveBeulke Tags: db2 plan 2,960 Views

Leverage DB2 Version 9 BASIC and EXTENDED Plan Stability Features

Last week I talked about leveraging the Version 9 DB2 Plan BASIC and EXTENDED plan stability features. I also commented that if you don’t have DB2 9 and are coming from DB2 Version 8 to DB2 10 that you can still save your DB2 access plans. If you are migrating from DB2 Version 8, move all your DB2 Plans to Packages and make copies of the Packages with different OWNERs or COLLIDs such as “SAVED” or something equally obvious. This way you can copy back, include the backup collection or manipulate your application to use these SAVED packages. Keeping the old SQL optimization and access path information is vital.

The following diagrams show how to setup a way save your SQL optimization access path and then back out a module. This worked for me a long time ago Version 3 or 4 and for a client with Version 7, so make sure you test out your setup and back out procedures. Then the process can be quickly executed by operations personnel with a REXX exec or library control process such as Endevor or other change management products. Since a picture is a thousand words below are two charts that illustrate how to set up a simple DB2 PLAN PKLIST access path preservation process.

Gene Fuh and Terry Purcell wrote an article describing this type of DB2 Plan technique and the CURRENT PACKAGESET options for protecting your access paths. "Insurance for Your Access Paths Across Rebinds" for further detailed explanation.

Remember DB2 Plan Stability with DB2 9 and DB2 10 is the best and simplest way to implement a method to protect your SQL Optimizer access paths. There are also software tools on the market for handling more complex backup and recovery situations. Use Version 10 DB2 Plan Stability as soon as possible, but there are several other techniques to protect your access paths and guarantee performance.

My DB2 10 information has been put into a collaborative book with information from Roger Miller, Julian Stuhler, Surekha Pureka, DB2 10 for z/OS – Cost Savings ….. Out of the Box.

Maintaining DB2 Query Performance Tuning within DB2 10

DaveBeulke Tags: query performance tuning 3,216 Views

Three Things to Do to Retain Your DB2 Query Performance

According to the majority of the DB2 10 Beta Customers, the performance figures for DB2 10 are true and sometimes better than the 5-10% saving right out of the box that is being advertised. But this is not to say that your DB2 10 migration and experience will be as good or better. Previous DB2 version migration horror stories abound and I have helped many clients tune and improve their DB2 system and query performance tuning. Some of these engagements have seen improvements in query performance tuning by correcting DSNZPARM settings that obviously got messed up. Did it happen during a migration, maybe? So here are three things you can do now in DB2 V9 that will help your application retain its current DB2 query performance tuning and get the most out of your DB2 10 system and application.

Gather Current Performance and DB2 Explain Output

To retain your query performance tuning going into DB2 10, you first need to understand and measure your current DB2 9 query performance tuning. Gather performance figures and EXPLAIN output for all your applications. Gather and understand the SQL access and overall processing of the application. Having these statistics before going into a DB2 10 migration is the first step to understand how much query performance tuning improvement your systems and applications are experiencing from the new DB2 10 features.

Leverage DB2 Version 9 BASIC and EXTENDED Plan Stability Features

To retain your query performance tuning leverage DB2 Version 9 BASIC and EXTENDED plan stability features. The DB2 9 BASIC and EXTENDED plan stability features are there to provide an easy way to preserve or fall back to a good package access path. By using this feature you can save off a good access path associated with the EXPLAIN information that was gathered in Step 1. Also by setting up the BASIC and EXTENDED plan stability features any special bind parameters or table/index statistics considerations can be exposed and documented before the migration to DB2 10. In addition the REBIND process will help your system make the transition to all DB2 packages from DB2 plans and bind everything in the current DB2 9. If you are migrating from DB2 Version 8, get all your DB2 Plans to Packages and make a copy of the Packages with a different OWNER or COLLID such as “SAVED” or something obvious. This way you can copy back, include the backup collection or manipulate your application to use these SAVED packages.

Determine Impact of DB2 10

Next, determine whether there is a high, medium or low probability that the DB2 packages will be able to leverage or be influenced by the new DB2 10 features. The DB2 10 improved parallel INSERT into multiple indexes feature will improve elapsed time but not CPU time. The new Stage 1 SQL Optimization improvements will potentially cut both elapsed and CPU time for your applications’ query performance tuning. Determine which of your individual application DB2 packages could see a benefit from the many DB2 10 features. (Go to my DB2 10 White Paper for a complete list of the DB2 10 enhancements.) Analyze your applications and understand which ones will benefit or may have potential issues before your DB2 migration. Use your Plan Stability BASIC and EXTENDED packages to use the best performing access path regardless of whether it is DB2 10 or DB2 9 and you will definitely have success and a good experience once your DB2 10 migration is complete.

Follow these three steps to insure your query performance tuning stays the same, or more likely, improves substantially.

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