Not strictly on topic, but fyi persistent connections are not supported by mysqli. It is added to PHP 5.3, but there is no direct support for it in eZ Publish yet ( will probably add support in 4.2).
Some nice reading on php, mysql and persistent connections:
The setting in eZ Publish decide how the application connect to the database. Basically it is mysql_connect or mysql_pconnect for persistent connections (while using MySQL driver).
Sure enough.
On oracle, the connection handshake is much heavier than it is in mysql, so persistent connections are usually faster/recommended.
They also have a lot of benefit in internal memory structures reusage and sharing. Otoh you will have to be careful tuning your resource allocation, as it is hard to put a clear limit on max persistent connections open from php to the db (apache max processes + cronjobs + cli scripts run on the spot +maybe more in cluster mode?), and all the connections will usually stay open eating your resources even if there are no users connected to the db, and you will have to be careful of connection state if there is a db restart while apache is running (all of this has been alleviated in recent php versions with some extra params in php.ini dedicated to tuning those aspects).
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