Tuesday, August 28, 2007

TEMPLATE Switching [DB2 9 for z/OS]

Next up in this on-going series covering the new features and functionality of DB2 9 for z/OS we will tackle the improvements that have been made to the IBM DB2 utilities.

A nice new feature that impacts multiple utilities is TEMPLATE switching. For those not familiar with templating, TEMPLATE is a utility control statement that enables the allocation of data sets for a LISTDEF (LISTDEF is the way you control the list of database objects for a utility execution). With the TEMPLATE statement you essentially specify data set naming conventions and allocation information without using JCL DD statements.

OK, so what is TEMPLATE switching? What it enables you to do is to specify different characteristics for image copies of varying sizes. So, for example, you can create a different template for low and high volume image copies. Here is an example:



//SYSIN DD *
TEMPLATE low DSN &DB..&TS..IC.D&DA..T&TI.
UNIT=DASD LIMIT(50 CYL,high)

TEMPLATE high DSN &DB..&TS..IC.D&DA..T&TI.

UNIT=TAPE

COPY TABLESPACE MY.SMALLTS COPYDDN(low)

COPY TABLESPACE MY.LARGETS COPYDDN(low)



Note the new parameter named LIMIT. This is what controls when the TEMPLATE is switched. In this example we set the LIMIT for low volume at 50 cylinders. When this is reached the TEMPLATE will be switched to the high volume template. Of course, you have the flexibility to control the limit by specifying whatever number is appropriate for your site as well as specifying it in CYL, GB, or MB.

It is important to understand that DB2 can only switch the TEMPLATE once, so you cannot have more than two templates.

Template switching is available for image copies produced by COPY, COPYTOCOPY, MERGECOPY, LOAD, and REORG. And you can set up template switching for both the COPYDDN and RECOVERYDDN.

3 comments:

Anonymous said...

You say
TEMPLATE low

and later
COPYDDN(small)

shouldn't that be the same name ?

Craig S Mullins said...

Good catch... I modified it so it is correct and consistent now.

Kane said...

Is this available with v8 under in any form?