Today we begin a multi-part series of blog posts taking a look at what is involved in
making database changes in a Db2 for z/OS environment. The first thing that
DBAs will need is the ability to change all the database objects supported
by Db2 for z/OS. There are numerous different types of database objects and structures that can be
created and modified by DDL, and at one point or another, DBAs are called upon
to create, alter, and drop every one of them.
But let’s dig a little deeper into what is required.
Assume that you are a Db2 DBA who has been given a request to make several changes
to database structures. The first thing you must do, of course, is to review
the requested changes to make sure they are
appropriate. Assuming they are, what is the next step?
You must determine how to go about making
each change. At a high level, there are three different types of schema changes:
- simple (or immediate),
- medium (or pending), and
- complex.
Simple changes can be
implemented immediately without requiring intervening actions. Medium changes
require a bit more work to implement by running a REORG, and then we have
complex changes that require an in-depth script for dropping and re-creating
the database object. But not every type of database change request can use each
type of schema change method. There are requirements and nuances in deciding
which method can be used when.
In our next blog post, we will discuss simple Db2 changes.
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