SQL Query Optimization - Part-9 (Covering Indexes)

To speed up query performance, use a Covering Index that covers (indexes) not just columns that will be used in the WHERE clause, but also columns that will be used in the projection list of the SELECT query.

See this video for a more detailed explanation.

Converting Regular Expressions to a DFA

Instead of writing anything on this most researched topic, I'm just posting some links here.

http://www.youtube.com/watch?v=dlH2pIndNrU
http://projectsseminar.blogspot.com/2011/06/regular-expression-to-dfa.html
http://en.wikipedia.org/wiki/Regular_expression#Implementations_and_running_times
http://swtch.com/~rsc/regexp/regexp1.html