Recipe for conference talks: add a buzzword like "sharding" and show how mysqlnd helps you with asynchronous queries. Only two PHP database extensions give you asynchronous queries: mysqlnd and Postgres. Slides (OpenOffice) from the International PHP Conference 2008 have the details about the asynchronous query API in ext/mysqli (using mysqlnd).

Mysqlnd Async Ipc2008

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Asynchronous, non-blocking IO is an old favourite. Although its an old idea, and it is a well known technology that is supported in many environments, it is still new for PHP database extensions. A year ago, I blogged about parallel and asynchronous queries in mysqlnd. Shortly after we had it implemented but never tested it and therefore never pushed it forward. Parallel queries, using a background thread in PHP, did not turn out to fly. But asynchronous queries have some potential.

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Read the rest of PHP: How mysqlnd async queries help you with sharding! (331 words)