What is a clustered index anyway?

Recovered from DotNetJunkies blog -- Originally Posted: Saturday, February 17, 2007

Wanted to drop a quick post for two reasons: 1) To prove I have not died, been abducted by aliens, or been confined to a room with soft, cushy walls and a nerf PC for my own "protection". 2) To give a plug for someone I had an opportunity to work with this past week.

Our shop was in need of some SQL Server performance tuning. Not having the expertise in house we called in an outside consultant. Not having had the best experiences with outside "experts" in the past, I was skeptical. However, Ray Rankins and his Gotham Consulting seem to be the real deal. Not living in the SQL world day in and day out, I tend to leave the "deeper thoughts" to the DBA's and worry about the procs doing what I need when I need it. However, when it does come down to a proc that is dogging our application down, it would be nice to really understand why one syntax or set of indexes works so much better than another. Usually the approach to tuning a long running proc from a developer standpoint is "Well, that sucks, let's try something else" and "Wow, that sucks a lot less, let's do that!" Speaking with Ray this past week I found a man who knows, and seems to care, about what is happening under the hood in SQL Server as much as I do about the inner workings of the CLR. The longer I work in this field the more I realize that this kind of person is hard to find. In one ten minute conversation I now have a really good idea what a Clustered vs. a Non-Clustered index is, why it matters, what situations you would want to use either of them etc. Ray has written "the book" [note: updated link to latest edition of book when recovering blog post -- AZ] on SQL Server and is just making the final edits on the SQL 2005 edition. I think I will add it to my ever growing stack of books to read one rainy day.

© Copyright 2009 - Andreas Zenker