Intel 7xx Servers, 170 Servers, AS/400 RISC Server manual Database Access, Os / Db

yThroughput - Orders Per Minute (OPM). Each order actually consists of 10 web requests to complete the order.

yOrder response time (RT) in milliseconds

yTotal CPU - Total system processor utilization

yCPU Zend/AP - CPU for the Zend Core / Apache component.

yCPU DB - CPU for the DB component

Database Access

The following four methods were used to access the backend database for the DVD Store application. In the first three cases, SQL requests were issued directly from the PHP pages. In the fourth case, the i5 PHP API toolkit program call interface was used to call RPG programs to issue i5 native DB IO. For all the environments, the same presentation logic was used.

yibm_db2 extension shipped with Zend Core for i that provides the SQL interface to DB2 for i.

ymysqli extension that provides the SQL interface to MySQL databases. In this case the MySQL InnoDB and MyISAM storage engines were used.

yi5 PHP API Toolkit SQL functions included with Zend Core for i that provide an SQL interface to DB2 for i.

yi5 PHP API Toolkit classes included with Zend Core for i that provide a program call interface.

When using ibm_db2, there are two ways to connect to DB2. If empty strings are passed for userid and password on the connect, the database access occurs within the same job that the PHP script is executing in. If a specific userid and password are used, database access occurs via a QSQSRVR job, which is called server mode processing. In all tests using ibm_db2, server mode processing was used. This may have a minimal performance impact due to management of QSQSRVR jobs, but does prevent the apache job servicing the php request from not responding if a DB error occurs.

When using ibm_db2 and the i5 toolkit (SQL functions), the accepted practice of using prepare and execute was utilized. In addition stored procedures were utilized for processing the purchase transactions. For MySQL, prepared statements were not utilized because of performance overhead.

Finally, in the case of the i5 PHP API toolkit and ibm_db2, persistent connections were used. Persistent connections provides dramatic performance gains versus using non-persistent connections. This is discussed in more detail in the next section.

In the following table, we compare the performance of the different DB access methods.

	OS / DB	i 5.4 / DB2	i 5.4 / MySQL 5.0	i 5.4 / DB2	i 5.4 / DB2
	ZendCore Version	V2.5.2	V2.5.2	V2.5.2	V2.5.2
	Connect	db2_pconnect	mysqli	i5_pconnect	i5_pconnect
				SQL function	Pgm Call Function
	OPM	4997	3935	3920	5240
	RT (ms)	176	225	227	169
	Total CPU	99	98	99	98
	CPU - Zend/AP	62	49	63	88
	CPU - DB	33	47	33	7
IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
© Copyright IBM Corp. 2008		Chapter 6 - Web Server and WebSphere			89