A new Technical Whitepaper "PHP Scalability and High Availability" is out on OTN
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. One of my talks last year pointed out that scalability doesn't just mean huge: it's the potential to be huge. You can use DRCP (it's free with 11g) even on small machines and take advantage of the savings it offers.
I shouldn't forget the new FAN support, also covered in the whitepaper. FAN adds an error detection capability that allows PHP to take advantage of Oracle RAC clusters or standby databases to handle workload when one node is unreachable. (You can also use FAN with single instance DBs, if you want). Other code changes in PHP OCI8 1.3 allow it to handle unusable connections better. Adding FAN event detection on top of this allows PHP to recover from such situations fast and proactively.
You can get PHP OCI8 1.3.2 Beta from PECL and install it on PHP 4 or 5, or simply just install a PHP 5.3 development snapshot (which has the new extension by default). The extension compiles with Oracle 9iR2, 10g or 11g client libraries. Oracle's standard cross-version compatibility is applicable. DRCP functionality is only available using Oracle Database 11g. FAN is available from 10gR2 onwards. You can use the DRCP and FAN features separately, together, or even not at all.