I'm taking notes from the MySQL core kernel talk:
The core has an architecture like:
Parser Optimizer Storage Layer The storage layer has a Handler and Handlerton. Handlers are the real storage engines but Handlerton is new in MySQL 5.1.
On startup MySQL calls main() and then a plugin init.
The plugin has a UDF handler for user defined functions. It also has a fulltext handler which was originally written for CNET. The fulltext handler allows one to parse out all BLOBs sent to the database. This seems like a cool way to add Lucene support to any type of MySQL storage engine.
There's a new super cool plugin named Daemon which one can use to embed daemons within MySQL. For example someone embedded Apache as a Daemon plugin so that you could get "show processlist" as XML via HTTP. The were going to call this raw but it was too …
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