I was doing some research this morning for some query tuning on a client system and I came across a couple of blog series with some excellent posts for those looking to learn more about query plans (and as a handy reference).

The first series is by Craig Freedman on the Query Processor team at Microsoft and discusses the various types of joins:

The second series is an ongoing series by Brazilian consultant Fabiano Amorim discussing all sorts (ha – no pun intended) of query plan operators – you can get the growing list of articles here.