Carlos Sierra's Tools and Tips

A question that I hear often is: “how to tune a query?”. It comes in several flavors, but what I usually read between lines is: I am new to this “sql tuning” thing, and I have been asked to improve the performance of this query, but I have no clue where to start.

Knowing about nothing on SQL Tuning is quite common for most DBAs. Even seasoned DBAs may stay away from SQL Tuning, mostly because they feel out of their comfort zone. In addition, I think SQL Tuning is like Sushi: You either love it or hate it! And same like Sushi, most would avoid it simply because they haven’t tried it. By the way, I am a Sushi lover but that is another story…

SQL Tuning 101

So, if you are like in square 1, and you are serious about learning SQL Tuning, where do you start? There are about a couple dozens of well recognized names on this space of SQL Tuning. Look at my blog roll to get some idea. The problem with this list is that most of the “gurus” walk on water and their very simple explanations require like tons of knowledge in related topics. Not bad if you are traveling the road from intermediate to advanced, but a newbie gets lost like in 5 seconds. There is also the risk of falling for all the misinformation you find in the internet written by some adventurous self-proclaimed “experts”.

I strongly suggest to start by reading the Concepts reference manual for your Oracle release, followed by the SQL Reference. Feeling comfortable writing SQL is a must. You don’t know SQL? Then, learn it first then move into SQL Tuning. If you have some Development experience that helps a lot. If you are a seasoned Developer you are half the way there already.

After reading the Concepts reference manual and becoming proficient in SQL, then get yourself a copy of the “Oracle SQL High-Performance Tuning (2nd Edition)” book written by Guy Harrison more than 10 years ago. Disregard the fact that the book is old. I like this book because it starts with the basics. It assumes nothing. I learned a lot from it when I first read it long time ago. If you search for it in Amazon just be aware the front-cover picture is incorrect, but the actual book is correct.

Another book I suggest is the recent one written by Stelios Charalambides. The title is “Oracle SQL Tuning with Oracle SQLTXPLAIN”. I like this one because it introduces SQLTXPLAIN like you would do with Sushi: Starting with a California Roll, then Sushi and last Sashimi. Also, you would get to learn of SQLTXPLAIN and how this FREE tool can help you to digest your dinner better… I mean your SQL Tuning.

Once you gain some experience doing some real SQL Tuning, then you can move to start reading endorsed blogs and books from the Sushi Masters. I hope you give it a try, and I hope you also get to love it!