new to CI, need advice on db connections

Sorry to answer late...
yes, you're right, I was misunderstanding php connection persistence

I had (to some extent still have) performance problems connecting CI to a middleware through postgresql odbc, and trying to catch what was causing horribly slow queries, I noticed on the server that other simple query tools opened and reused a single connection while CI opened a new one at every page refresh... and I thought that it could be to something in the php/odbclinux/postgresql driver due to my relative inexperience with odbclinux, postgresql ad CI.

It turned out that CI was fine, and the problem was between linux odbc driver and the middleware, mainly.

Middleware is Jboss Teiid (http://teiid.jboss.org/), btw, and after several thread posts in their support forum, we spotted a coulple of problems, and they fixed the most troubling ones in a new beta version, which I'm testing. See https://developer.jboss.org/thread/268880.

While Teiid is much more performant through (eg) jdbc and odata, the same queries through its emulated odbc/postrgresql interface were much, much slower. Now is better, even if not yet perfect, and I'm going to learn more of CI.

Thank you, all, and feel free to suggest me any resource that could help in this respect,

Marco