Craig S. Mullins
Database Performance Management
The Buffer Pool
By Craig S. Mullins
“The Buffer Pool” will be a regular feature of PLATINUM SYSJOURNAL. The purpose of this column is to disseminate tips, tricks, techniques, rumors, and all-purpose information about DB2 for OS/390. If you have anything to contribute, please e-mail me at firstname.lastname@example.org.
APARty Going On!
there a favorite feature of Version 6 of DB2 for OS/390 that you simply cannot
wait to have? Well, many of the new features announced for V6 are being added to
V5 via APARs. So you might not have to wait until V6 becomes generally available
(due in June 1999)! For example, APAR #PQ15682 allows DB2 utilities to be run as
a WLM-managed stored procedure. And APAR #PQ18543 increases the DSMAX limit to
be greater than 10,000.
can check for yourself what new functionality has been added to DB2 through
APARs by going to IBM’s web site. The following URL provides the details:
Early SQLJ Bird Gets the Worm!
a related news byte, SQLJ support was announced for DB2 V6, but IBM has
announced early availability of SQLJ support in DB2 V5 via APAR #PQ19814. SQLJ
complements JDBC to enable both static and dynamic SQL in Java code. JDBC is
dynamic; SQLJ is static. For more information or to download SQLJ, visit:
the DB2 Catalog
has been possible to reorganize the DB2 Catalog table spaces using the REORG
utility since DB2 V4. But don’t go overboard and spend too much time here! I
mean, you had no REORG capability on the system catalog for more than a decade
and your DB2 subsystems survived. I’d recommend reviewing the DB2 Catalog for
reorganization no more than once a year unless you have made huge changes to
your DB2 environment that could have impacted the system catalog table spaces.
For example, adding a large number of new DB2 databases or applications could
cause inefficiency in the DB2 Catalog.
DB2 Mailing List
with an interest in DB2 for OS/390 should belong to the DB2-L mailing list.
Simply by subscribing to the mailing list, pertinent information is sent
directly to your email in-box. Postings will begin to arrive in your email box
from a remote computer called a list server. The information that you will
receive varies - from news releases, to announcements, to questions, to answers.
Be careful, though, because much of it is just other users’ opinions and not
the gospel from IBM. Users can send and respond to DB2
mailing list messages. Responses are sent back to the list server as
email, and the list server sends the response out to all other members of the
mailing list. To subscribe to the mailing list, simply send an email to the
appropriate subscription address, requesting a
issuing the preceding command, the list server will send you a message asking
you to confirm the subscription. When you do, information will quickly begin
flowing into your email box (perhaps at a much quicker rate than you can
reasonably absorb). Literally,
of this volume, I also recommend digesting your DB2 mailing list emails. A
digest is an accumulation of the day’s messages sent as one big email. The
benefit of digesting is that instead of receiving multiple daily messages from a
mailing list, only one daily digest is sent. Because the DB2 list is usually
quite active, you may receive dozens of emails daily if you don’t choose the
digest option. To request digesting, send an email to the subscription address.
The digest request must be made after you have successfully subscribed to the
mailing list. For the DB2 mailing list, send the following message to the
are drawbacks to digests: threads can be hard to follow, it is more difficult to
respond to messages, and the digest can become quite large. But the benefit of
getting just one message a day usually outweighs the negatives!
Thank you for reading this installment of “The Buffer Pool.” And remember, we want to make this column your place to go for the scuttlebutt on DB2 for OS/390. So contact us with any tips, tricks, techniques, or rumors. See you next issue!
(Actually, this was my last article for PLATINUM technology… Shortly after publication PLATINUM was acquired by CA and I left the company. I will not be writing The Buffer Pool for SYSJOURNAL any longer.)
© 1999 Craig S. Mullins, All rights reserved.