2.7.3 Connection Pool Sizing Guidelines

OHI Components utilize WebLogic Data Sources & Connection Pools to connect to the database. The number of connections in the Connection Pool should be properly sized. This paragraph contains guidelines for that sizing exercise.

2.7.3.1 Connection Pool management

The connection pool is managed by the WebLogic application server. For example, WebLogic may temporarily test a connection before it is handed to the process that requested it. For determining the size of the connection pool the total amount of connections is corrected for this overhead by increasing it with 30%.

2.7.3.2 UI Related Connection Pool Sizing

The number of connections for servicing UI requests depends largely on the number of (concurrent) users. Roughly, servicing a user's request requires the use of one connection. After the system's response is completed "think time" (before the user initiates a follow-up request) needs to be taken into account. Oracle assumes that a user spends 75% of his time evaluating the response and for initiating the next activity. The formula for determining the number of connections for servicing UI requests is: number of concurrent users * (100-75%) with a minimum of 50 connections for handling UI requests.

2.7.3.3 Processing Related Connection Pool Sizing

For task or activity processing, the number of database connections required is similar to the amount of processing threads.

2.7.3.4 Web Services Related Connection Pool Sizing

For handling Web Service request, OHI Components use more than one database connection. For auditing purposes, information is logged using a separate connection. As a result, for handling Web Services requests the number of database connections required is: the number of concurrent requests * 2.

2.7.3.4.1 Sample Worksheet for connection pool calculations

	Users	40
UI Database Connections	50	40 * 0.25 = 10 (less than minimum of 50)
	Processing Threads	15
Processing Database Connections	15	15
	Number of concurrent Web Services Requests	15
Web Services Database Connections	30	15 * 2
Total number of Database Connections	137	(50 + 15 + 30) * 1.3 (management overhead)

As a result, the maximum number of database connections in the pool should be set to 137. Make sure that the number of sessions that the database can accommodate is larger than that number.