features in PHP

Hi all, Since I couldn't find solid docs on the web about this... I was curious if PHP in Apache 2.0 implements a couple features that I'm used to using in the AOLserver world: -- Can PHP hold a global cache that's accessible for all threads? -- How well do persistent database connections work in PHP? I recall some tests saying that persistent connections with MySQL were actually slower in PHP 4.0.x than building and tearing down a MySQL connection each time you wanted to query info from the database. -- What are the performance differences (if any) between pooled connections to MySQL vs Postgres? Thanks! Justin