Intel AS/400 RISC Server, 170 Servers, 7xx Servers manual Database Isolation Levels, Zend Platform

Conclusions:

1.As stated earlier, persistent connections can dramatically improve overall performance. When using persistent connections for all transactions, the DB CPU utilization is significantly less than when using non-persistent connections.

2.For any transactions that run with autocommit turned on, use persistent connections. If the transaction requires that autocommit be turned off, use of non-persistent connections may be sufficient for pages that don’t have heavy usage. However, if a page is heavily used, use of persistent connections may be required to achieve acceptable performance. In this case, you will need a well designed transaction that handles error processing to ensure no commits are left outstanding.

Database - Isolation Levels

Because the transaction isolation level determines how data is locked and isolated from other processes while the data is being accessed, you should select an isolation level that balances the requirements of concurrency and data integrity. DB2_I5_TXN_SERIALIZABLE is the most restrictive and protected transaction isolation level, and it incurs significant overhead. Many workloads do not require this level of isolation protection. We did limited testing comparing the performance of using DB2_I5_TXN_READ_COMMITTED versus DB2_I5_TXN_READ_UNCOMMITTED isolation levels. With this workload, running under DB2_I5_TXN_READ_COMMITTED reduced the overall capacity by about 5%. However a given application might never update the underlying data or run with other concurrent updaters and DB2_I5_TXN_READ_UNCOMMITTED may be sufficient. Therefore, review your isolation level requirements and adjust them appropriately.

Zend Platform

Zend Platform for i is the production environment that ensures PHP applications are always available, fast, reliable and scalable on the i platform. Zend Platform provides caching and optimization of compiled PHP code, which provides significant performance improvement and scalability. Other features of Zend Platform that brings additional value, include:

y5020 Bridge – API for accessing 5250 data streams which allows Web front ends to be created for existing applications.

yPHP Intelligence – provides monitoring of PHP applications and captures all the information needed to pinpoint the root cause of problems and performance bottlenecks.

yOnline debugging and immediate error resolution with Zend Studio for i

yPHP/Java integration bridge

By automatically caching and optimizing the compiled PHP code, application response time and system capacity improves dramatically. The best part for this is that no changes are required to the take advantage of this optimization. In the measurements included below, the default Zend Platform settings were used.

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
© Copyright IBM Corp. 2008	Chapter 6 - Web Server and WebSphere	91