Best PHP DAL (data abstraction layer) so far

Question

What is the best PHP DAL (data abstraction layer) so far developed under any open source project which we could re-use with good faith?

I am finding it hard to choose a DAL for my application that sufficiently supports abstraction to most common databases systems (MySQL, PostgreSQL, MSSQL, Oracle, etc) and is:

1. widely tested,
2. has good interface (readable method names, good parameter passing strategy),
3. fast,
4. lightweight,
5. providing cache (e.g integrates with Memcache or supports a good caching mechanism),
6. open-source license,
7. should have adapters for at least MySQL/MySQLi (non-PDO based)

Some of the libararies to consider:

• PHPBB DAL http://wiki.phpbb.com/Database_Abstraction_Layer
• Joomla DAL http://api.joomla.org/Joomla-Framework/Database/JDatabase.html
• ADOdb http://phplens.com/adodb/
• Zend_db
• Doctrine (downside only supports PDO_*)
• any other DAL used/developed under any open-source project/branch

Please don't consider:

• PDO
• All ORMs (however, Doctrine seems to have a separate DAL besides ORM)

Answer 1

If you can do with PHP 5.3, I would highly recommend Doctrine DAL, it's built on top of PDO, so you get the same performance plus a great API.

Update: If Doctrine is not good, you can try MDB2. It has drivers for most of the popular RDBMS, a robust API, great docs and a huge user base:

• MySQL
• MySQLi (PHP5 only)
• PostgreSQL
• Oracle
• Frontbase
• Interbase/Firebird (PHP5 only)
• MSSQL
• SQLite