Thursday, February 7, 2013

Logical Query Processing

Well, that's been a while since my last post.. A new year, new chances!

Opposed to physical query processing which follows the order of the statements:
SELECT .. FROM .. WHERE.. GROUP BY ..)
logical query processing processes the statements in the following order:
FROM .. WHERE .. GROUP BY .. SELECT ..

Last week I saw this excellent poster from (who else then) Itzik Ben Gan, writing down the phases of logical query processing in T-SQL in a flow diagram.


You can download the original poster here.