On 7/30/2011 1:07 PM, John Du Hart wrote: I'd like to see PDO support[1] in addition to MySQLi, reasons being is that: a) PDO is a common interface for all types of databases (supports MySQL, Postgres, SQLite, and bunch of others) as long as the appropriate drivers are installed, which would allow us to cut down on the amount of code in the Database* classes considerably (to the point where most of the methods could probably be implemented in DatabaseBase without any issue) b) PDO ships with PHP 5.1+ (and MediaWiki requres 5.2+), although it seems that only the SQLite driver is installed by default. Haven't checked packages to see what the various distros all enable yet. c) Both PDO and MySQLi support "prepared" statements, which could let us introduce a form of statement cache so that if we need to execute the same query multiple times except with different parameters, there is less overhead involved since the statement is already prepared and just needs the data values to use. Another bonus of prepared statements is that it properly escapes everything according to whatever database engine you happen to be using when you substitute in parameters. d) Supporting both PDO and MySQLi will allow MediaWiki to be installed in more server configurations, as some hosts may have one enabled but not the other. I think that they should be considered separate db types as far as the installer is concerned so that users can choose between the one they wish to use (we can of course mark the old mysql one as "not recommended" to coerce users into picking one of the other two if they have them available for use). [1] http://www.php.net/manual/en/book.pdo.php

That statement cache needs persistent connections, which are somewhat expensive. Otherwise you're doing two roundtrips instead of one, and there's not much performance win anyway. I don't think that has been an issue lately. Domas