Top Ten Things You Need to Know About DB2 For z/OS
For DB2 DBAs and Developers
There is a veritable boatload of information and details about DB2 for z/OS available to you. But can you digest all of it? Wouldn’t it be nice if you could focus on the things that were the most important for you to know instead of wading through thousands of pages of manuals, web pages, and presentations? This session will distill the essence of what you need to know into the top ten most important issues for the two biggest categories of DB2 users: application programmers and database administrators.
Join Craig Mullins and Datavail for this webinar as we:
- Count down the top ten most important things you need to know
- See what is most important for DBA, developers, and managers to understand about DB2 for z/OS
- Understand the hierarchy of DB2 performance tuning objectives
Show Transcript
Below is a preview of the webinar transcript.
Next, join predicates. If you've got a series of tables that are being joined together, and you should, this goes back to the first rule: let SQL do the work. Do the joins instead of multiple sequel statements that are then cobbled together in the program. When you've got multiple tables being joined in an SQL statement, be sure that you are providing appropriate joined predicates. What I mean by that, well if you have table A, B, and C, you should have wear clauses, or on clauses depending on how you close the joints, that connect table A to B, table B to C, or table C to A, C to B. There should be a path through all three of those tables or all X of those tables regarding the number of tables you have in the joint.
If you don't have joint predicates, what you're doing is causing DB2 to do a Cartesian product. A Cartesian product says, "Take all the rows in this table and join them to all the row in that table." It's going to take a lot of resources to do that and probably give you the wrong results. Whatever you've got joined, go back, check you got passed you where or on clauses.
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