Christopher Jones has pointed out a new whitepaper that's been published by oracle about the scalability the connection pooling affords for current versions of PHP.

The whitepaper talks about the changes in the PHP OCI8 1.3 extension, explains some of the concepts behind DRCP and FAN, and gives best practices and tuning tips. It includes a new PHP benchmark which shows up to 20,000 connections being handled by Oracle on commodity hardware using only 2G RAM.

The paper also talks about the FAN support that's built in - the ability for PHP to use the Oracle RAC cluster functionality to make for high availability (switching between nodes). The latest beta with all of this functionality in it can be grabbed from its page on the PECL site.