Monday, December 15, 2014

The Wizard of Userville and the DB2 Developer's Guide

Once upon a time there was a kingdom called Userville. The people in the kingdom were impatient and wanted to know everything about everything—they could never get enough information. Life was difficult and the people were unhappy because data was often lost, and even when it was available, it was often inaccurate and not easy to access.
The King decided to purchase DB2, an advanced tool for storing and retrieving data. With DB2 the Users could process their data and turn it into information. “This,” he thought, “should keep the people happy. DB2 will solve all my problems.” But he soon found out that special knowledge was necessary to make DB2 work its wonders. Nobody in Userville knew how to use it properly.

Luckily, a grand Wizard living in a nearby kingdom knew many mystical secrets for retrieving data. These secrets were a form of magic called SQL. The King of Userville summoned the Wizard, offering him many great treasures if only he would help the poor Users in Userville.

The Wizard soon arrived, determined to please. Armed with nothing more than SQL and a smile, the Wizard strode to the terminal and uttered the magic words:

    SELECT E.EMPNO, E.FIRSTNME, E.LASTNAME, D.DEPTNO, D.DEPTNAME
    FROM   DSN81010.DEPT  D,
           DSN81010.EMP   E
    WHERE  E.WORKDEPT = D.DEPTNO;

A crowd gathered and applauded as the desired information began pumping out of the terminal. “More, more,” shouted the data-starved masses. The Wizard gazed into the screen, and with amazing speed effortlessly produced report after report. The King was overheard to say, “You know, this is just too good to be true!” Everybody was happy. The Users had their share of information, the King had a peaceful kingdom, and the Wizard had his treasures and the respect of the Users.

For many months, the Users were satisfied with the magic of the great Wizard. Then, one day, the Wizard disappeared…in a jet to the West Coast for 150 grand a year—and a bunch of stock options. The people of the kingdom began to worry. “How will we survive without the magic of the Wizard? Will we have to live, once again, without our precious information?” The Wizard’s apprentice tried to silence the crowd by using his magic, but it wasn’t the same. The information was still there, but it wasn’t coming fast enough or as effortlessly. The apprentice was not yet as skilled as the great Wizard who had abandoned the kingdom. But, as luck would have it, one day he stumbled upon the great Wizard’s diary. He quickly absorbed every page and soon was invoking the Wizard’s magic words. And all was well again.

Well, life is not always that simple. Departing Wizards do not often leave behind documentation of their secrets. But...


Many of you who have purchased my book, DB2 Developer's Guide, will recognize the story recounted above because it starts the book off in Chapter 1. The idea being that the rest of the book is the Wizard's guide to DB2 for z/OS... 

If you use DB2 for z/OS for a living and you have never read DB2 Developer's Guide, maybe it is time to treat yourself to an early present for the holidays? The book comprises more than 1500 pages of in-depth DB2 knowledge and information. Over the course of 46 chapters DB2 Developer's Guide covers:
  • SQL Techniques, Tips, and Tricks
  • DB2 Application Development
  • DB2 In-Depth (an under the covers look)
  • DB2 Perfromance Monitoring
  • DB2 Utilities and Commands
  • DB2 Tools and Organizational Issues
  • Distributed DB2
  • and much, much more

The book has been in print for more than 20 years now and has been published in 6 different editions over that span. The current edition is the 6th edition published by IBM Press.


So continue and take the next step toward becoming a DB2 Wizard by getting your own copy today!

2 comments:

Rikdeb Mukherjee said...

Happy New Year !!..
I am in search of one answer regarding locking.I was going through the link http://www.toadworld.com/platforms/ibmdb2/w/wiki/6655.lock-sizes-and-types.aspx and the first para says " DB2 does not take transaction locks on indexes at all, but uses data-only locking. "
Could you please explain a bit what is a 'data only locking'. Also, when data is fetched from index only, does db2 apply the same locks (S,IS) on the index like it does on TS,or Table?.. Would be waiting for your answer.. Thanks in advance!!

Craig S. Mullins said...

Here is a link for you to read through on DB2 data only locking: http://www-01.ibm.com/support/knowledgecenter/SSEPEK_11.0.0/com.ibm.db2z11.doc.perf/src/tpc/db2z_indexanddataonlylocks.dita