The Tao of DB2

The Tao of DB2
Achieving Balance & Understanding with DB2
Craig S. Mullins
Mullins Consulting, Inc.
http://www.CraigSMullins.com
Session: B8
Wed, May 25, 2005 @ 8:30 AM - 9:40 AM
Platform: DB2 for z/OS

2
The Tao of DB2
Achieving Balance & Understanding with DB2
Listen, well, my intern and you
too can achieve balance and
understanding with DB2.
Will this take long?
I already told our
manager I know
this stuff.

3
Tao Te Ching
• Ancient Chinese philosophy of life.
• Written by Lao Tzu over 2000 years ago.
• The Tao, or the Way, is a universal power through which all
life flows.
• The Tao Te Ching proposes a model by which the individual
and society can embody a philosophy to achieve a harmonious
and balanced existence.
• This presentation will attempt to apply some of the concepts
of the Tao to DB2 and database administration.

4
Understanding the Tao
• What is Tao?
• “The Way”
The way that can be spoken of
Is not the constant way;
The name that can be named
Is not the constant name.

5
Tao Terms
• Tao – a nonsense syllable; it represents the mystery we can
never understand
• Li – the patterns of nature
• Tzu-Jan – “by itself so”
• Wu-Wei – not forcing
• Te – virtue; skill at living
Understanding the Tao of DB2 and armed with database Te, the DBA uncovers the Li of the
application programs and removes the SQL tweaks that were working against Wu-Wei and the
system experiences a performance gain that is Tzu-Jan.

6
The DB2 that can be mastered, is not
the DB2 that runs on z/OS. One who
excels at tending to his lack of
understanding can begin to embrace the
glory of DB2, and call himself DBA.
I do not
understand…
The Taoist DBA
The Intern

7
Indeed it is long since
the people have been perplexed.
-Lao Tzu
• “One could study for ten thousand years and travel the four
corners of the globe and yet still be ignorant,” said the Taoist
DBA.
• Lesson: DB2 is a large, complicated piece of systems
software. No one can fully understand everything it is and can
do.
• When you think you understand DB2 a new version will come out
with new features and changes to the old ways.
• Always be open to learning; never assume you know everything.
The term Tao
refers to the vast and great…
-Chu Hsi

8
Were it (Tao) definable, it could then be
used to obviate conflict…
-Lao Tzu
• The users were howling, the system was not responding.
“What should I do?” screamed the intern. The Taoist DBA
pulled up his PDS member and pressed <ENTER>. “Oh, has
this happened before?” asked the intern. “How many times?”
said the DBA.
• Lesson: Minimize conflicts through written standards and
goals; prepare for recurring problems with predefined scripts.
• SLAs
• DBA standards
• Development and SQL standards
• Canned jobs

9
The more laws & restrictions there are
the poorer people become.
-Lao Tzu
• “I followed the corporate standards
to the letter, but it doesn’t work,” spat
the frustrated intern. “The best thing
about standards,” said the Taoist DBA,
“is that there are so many of them from
which to choose.”
• Lesson: Although it is advisable to create
DB2 standards, for every standard there
is a reason to make an exception.
If nothing within you stays rigid,
outward things will disclose themselves.
-Kuan-Yin

10
Straightforward words seem paradoxical…
-Lao Tzu
Lesson: Sometimes
the manuals are not
easy to understand
until you get used to
the terminology &
the writing style.
• Do not panic.
• Augment manuals
with other material.
• Learn by doing.
The term li includes the innumerable
vein-like patterns in the Tao.

11
Having examined the appearance of the thing,
one seizes upon its essence.
-Lao Tzu
• “The mouse in the trap squeals with pain,” explained the
Taoist DBA, “not first examining the cheese for a spring.”
• Lesson: Know your data; monitor your systems.
• Distribution
• Static vs. dynamic data
• Indexes
• Cardinality
• CPU usage
• Buffer Pool efficiency; memory
usage
• SQL: static & dynamic
• System parameters
The sage…avoids extremes and excesses,
and does not become complacent.
-Lao Tzu

12
So I must document, but
remain flexible while
always learning this thing
I will never fully master?
The Taoist DBA
The Intern
You begin to grasp yet
you are far away from
being enlightened. I
cannot yet retire with
a good conscience,
young intern. We must
continue the lesson…

13
And so they begin to work on a request
for a new database…
is
rented
under
reports to
completes
rents /
is in
employed by
receives
makes
rents under
is made on
is rented as
CUSTOMER
CustomerNum
Name
Address
Phone
CreditCardNum
CreditCardExDate
StatusCode
MOVIE
MovieNum
Name
Director
Description
Star
Rating
Genre
Rental Rate
STORE
StoreNum
Manager
Address
Phone
EMPLOYEE
EmployeeNum
Name
Address
Phone
SocialSecNum
HireDate
Salary
Supervisor (FK)
PAYMENT
Payment Transaction Num
Type
Amount
PaymentDate
Status
MOVIE RENTAL RECORD
Rental Record Date
Rental Date
Due Date
Rental Status
Rental Rate
Overdue Charge Amt
MOVIE COPY
Movie Copy Num
General Condition
JoinDate
We begin
with the data
model…

14
What is springs from what is not.
-Lao Tzu
• “Where do I begin,” asked the intern. The Taoist DBA
replied, “Begin at the beginning… and continue working until
you reach the end.”
• Lesson: Every database must begin its life as a well-designed
data model. It must be physically implemented with an
understanding of the capabilities of DB2.
• An improperly designed DB2 database can cause horrible
performance problems.
• From logical data model to physical implementation, all steps must be
planned and well thought-out for success to follow.
• Errors in planning at the initial stages can result in disaster at later
stages, requiring re-design and/or re-writing code.

15
Lay plans for the accomplishment of the
difficult before it becomes difficult; make
something big by starting with something small.
-Lao Tzu
• “That programmer from accounting is asking for more
changes; should I stop what I am doing to work on
those?” grumbled the intern. “When it is too late to do
it right, we must inevitably do it over,” said the Taoist
DBA as he nodded noncommittally.
• Lesson: Take the time to plan the database implementation
including both database design and program design.
• If you proceed without knowing the requirements you will be
continually changing everything forever.

16
Thus Something and Nothing produce
each other…
-Lao Tzu
• “Does this DDL look right,” asked the intern. “Can one know
what one does not know? The vessel is not empty, nor is it
full. We may even know not where the vessel is…” the Taoist
DBA rather cryptically muttered.
• Lesson: Define each column carefully.
• Must a value be known?
• NULL or NOT NULL
• Is there a valid default value for the column?
• What is the data?
• Numeric, alphanumeric, date/time

17
Use what is naturally useful.
-Chuang Tzu
• “I do not know which of these options to choose. Should I just
use the defaults,” moaned the intern. “I’m for whatever is
right,” exclaimed the Taoist DBA. “Choose
wisely and we will not have this conversation
again.”
• Lesson: Understand every option at your
disposal before choosing any parameter.
Use the one that best matches the needs of the
database, the application, or the situation.
• Avoid DB2’s defaults.
All things can do something, and
can equally succeed.
-Kuo Hsiang

18
Let everything be allowed to do
what it naturally does,
so that its nature will be satisfied.
-Ching Hao
• When the intern asked “Why will DB2 not allow SPACES in
this DATE column,” the Taoist DBA smiled and tried to answer
the intern in writing. But he wrote his answer with a Fig
Newton.
• Lesson: No kludging; use the features of DB2 as they were
designed and meant to be used. Examples:
• Use DATE, TIME, and TIMSTAMP for chronological data
• Use numeric data types for numbers, character data types for alphanumeric
• Use referential constraints (declarative RI) and CHECK constraints instead of
using programs to enforce constraints
• Use whatever number of the 60 buffer pools your implementation
may need (instead of only BP0)

20
Though adjoining states are within sight of
one another…the people of one state will
grow old and die without having had any
dealings with those of another.
-Lao Tzu
• Confused, the intern asked “But when should I partition the data?” The
Taoist DBA slapped the intern and asked if it would have been beneficial
for a partition to have existed between them.
• Lesson: When the amount of data is so large as to have
a reasonable expectation that you will need to administer
it in “pieces” consider partitioning.
• There is no “mythical” cutoff of pages/rows after which
you must partition.
• Largest simple or segmented TS is 64 GB
• Largest partitioned TS is 128 TB.

21
When the consistency of the way is known,
the mind is receptive to its states of change.
-Lao Tzu
• The intern asked “Why is my data corrupt?” and the Taoist
DBA answers “It is always the drunkard who knows not why
he is slumped on the floor.” Learning, the intern slowly
realizes he has only himself to blame.
• Lesson: Database constraints improve data integrity. When RI
and CHECK constraints are defined to the database then DB2
is receptive to changes in the state of the data and manages
them appropriately.
Yield, and maintain integrity;
Be whole and all things come to you.
-Lao Tzu

22
Therefore he discards the one
and takes the other
-Lao Tzu
• “With all of these constraints, my database will never get out
of sync, will it?” queried the intern. The Taoist DBA
continued to balance his checkbook, looking for that missing
penny.
• Lesson: Even with constraints sometimes our data will lack
integrity (e.g.., Loading without enforcing constraints.)
• Be prepared to get things re-synchronized:
• Used the CHECK utility with the DISCARD option to remove data
that does not match the constraint.

23
It is easy to maintain a situation
while it is still secure.
-Lao Tzu
• The Taoist DBA stole the intern’s lunch money to teach him
the need for security. “I am hungry,” said the intern. “Yet I
am not,” said the Taoist DBA.
• Lesson: Understand the security and authorization needs of
your DB2 databases and applications before you develop
them, far in advance of moving to production.
• Build programs with knowledge of DB2’s abilities.
• Multi-level security (DB2 V8) can provide row-level security.
• Views possibly can help, too.
• Using secondary authorization Ids can greatly simplify your DB2
security implementation.
• Cooperation with RACF/ACF2 security staff is essential.

24
To accept the irrevocable
is to let go of desire.
-Lao Tzu
• The test system was hosed. The intern had revoked the
authority of an application DBA who had quit last month.
“Why can no one access their tables?” asked the intern. “Can
you touch what is not there?” asked the Taoist DBA.
• Lesson: Be careful with DB2 security. When revoking an
authorization GRANTed by a user having WITH GRANT
OPTION, the REVOKE will cascade and also remove all the
authority the user granted.
• Consider disallowing WITH GRANT OPTION, especially in
production systems.

25
The database is built, tested,
and ready to deploy…
is our work done?
The Taoist DBA
The Intern
As the Winter approaches
the squirrel busies him-
self gathering nuts for
the barren season. He is
ready should misfortune
befall him… you are not.

26
Lay plans for the accomplishment of the
difficult before it becomes difficult; make
something big by starting with something small.
-Lao Tzu
• “Be ready,” said the Taoist DBA “for everything, because
eventually everything will happen.” The intern wept.
• Lesson: Be sure to schedule appropriate backups for each and
every table space; understand the volatility of the data and the
type of recovery that may been needed.
• Incremental versus full backups
• More than once-a-day, Daily, Weekly, Monthly, etc.
• Test the recoverability of your databases

27
When the people lack a sense of awe, then
some awful visitation will descend upon them.
-Lao Tzu
• “This backup stuff is pretty easy,” said the intern. “I’m outta
here,” was the sole reply of the Taoist DBA, and all that
remained was his spinning chair and a cooling mug of coffee.
• Lesson: Keep your disaster recovery plan up-to-date and be
sure to test it at least annually. Take nothing for granted.
• Remember always that contingency planning and recovery from a
disaster is a complex and time-consuming endeavor.
…he is fit to lead
who takes the country’s
disasters upon himself.
-Lao Tzu

28
Achieve success, but without force.
-Lao Tzu
• “I’ve heard people say ‘If it don’t fit, force it’,” said the
intern. And his Taoist mentor told him to force his mouth
shut.
• Lesson: Force fitting a resolution to a problem is not a wise
approach for the DB2 professional.
• Example: Resolve the problem instead of forcing
-START DATABASE (DSN8D81A)
SPACENAM (DSN8S81E) ACCESS (FORCE)
RECP  run the RECOVER utility
CHKP  run the CHECK utility 


29
If you would have a thing shrink
you first must stretch it.
-Lao Tzu
• “How much storage space is needed for this database,” asked
the intern. “What amount of space is required to store sand?”
replied the Taoist DBA. “How much sand – a grain or a whole
beach?” asked the intern. “Exactly,” replied his mentor.
• Lesson: Plan for database growth. Understand how the business
use of the database will cause data to expand or contract. Use
DB2 features to your advantage.
• Free space – allow sufficient free space to grow
• Compression – reduce the size of larger objects

30
Reduce the size and population
of the state.
-Lao Tzu
• Lesson: Prepare a data archival plan for each and every DB2
table in your system.
• Less data in a table space can result in more efficient access; as old
data gets archived…
• …there may be more relevant rows per page, improving read efficiency;
• …table space scans will run faster;
• …backup/recovery and REORG will run faster;
• …less disk space may be needed.
• Archiving stale, or outdated, information can enhance the accuracy of
database reporting and queries.
• Archived data can be kept on cheaper storage media.
• The plan may be  No Archiving.

31
OK, proper backups are
scheduled and we have a
DR plan; it is even
tested.
Surely we are ready to
move on?
The Taoist DBA
The Intern
Is the work of the bumble-
bee ever completed?
There is always more
nectar to gather.
Performance

32
Life is the blended harmony
of yin and yang.
-Chuang Tzu
• When the intern’s tuning attempt does not solve the problem,
he consults the Taoist DBA for assistance. “You glue wings to
your arms, yet you cannot fly.” Confused, the intern moped
away, and the problem persisted.
• Lesson: Most performance problems are not solved on the
first try; many performance problems require multiple things
to be changed for results to be achieved.
• Example: Adding an index to optimize a query. If it is static,
you have to REBIND. If not, you might also have to modify
the query, too.
• DB2 Performance = System + Database + Application

33
It is supplied with all its needs
and is constantly at ease
because it follows its own plan…
-Lao Tzu
• Lesson: The DB2 optimizer formulates access paths which it
packages into plans and follows for optimum efficiency.
• Build effective SQL that encompasses as many of the “needs” of the
application as possible; this eases performance tuning.
• As data patterns change and DB2 evolves new features, rebinding a
new “plan” can quickly adapt the program to the data and updates.
• The novice, with his data access built into his program is ill at ease as it
takes long hours to adapt to changes.

34
The unseen design of things is more
harmonious than the seen.
-Heraclitus
• The intern requested of his teacher, “Teach me all the
mysteries of the Optimizer.” The Taoist DBA replied “A
mystery is named such because it cannot be totally
understood.”
• Lesson: sometimes that which we cannot understand 100% is
still well-designed and required.
• No one (outside of IBM) fully understands every nuance of the
optimizer
• We can learn general rules, one of which is to entrust the optimizer to
create more efficient access than we can write ourselves
• Guideline: Do as much work as possible within the SQL
• Guideline: DB2 code is more efficient than my/your code

35
• “The programmers continue to blame DB2 for their errors,”
lamented the intern. “A monkey chatters until you give it a
banana. Then the monkey chatters again tomorrow.”
• Lesson: Let DB2 be DB2… understand and
use DB2 as it is meant to be used; education
is required.
• Every day is an opportunity to learn.
• The parable of the overconfident programmer…
• To not learn from your experiences is to
relegate one self to never understanding the
nature of DB2
The more it works, the more comes out.
-Lao Tzu

36
Without a door, the room cannot be entered,
and without windows it is dark.
Such is the utility of non-existence.
-Lao Tzu
• Lesson: Use the EXISTS construct for efficient existence
checking. Example:
• As long as Jones exists, the query succeeds; DB2 need not find all of
the Jones, just one (any one).
SELECT 1
FROM SYSIBM.SYSDUMMY A
WHERE EXISTS (SELECT 1
FROM DSN8810.EMP B
WHERE LASTNAME = ‘JONES’
AND A.IBMREQD = A.IBMREQD);
It is only by means of being
that non-being may be found.
-Lao Tzu

37
Keep a thing in order before disorder sets in.
-Lao Tzu
• “When shall we REORG the table space?” asked the intern.
“When we must, and only then,” replied the Taoist DBA.
• Lesson: Create a plan for each DB2 object based
on an understanding of the activity that will be
performed on it. Monitor DB2 Catalog statistics to
determine when to reorganize.
• Is the object static or dynamic?
• Static (no new rows) = no free space
• Changes? Rare; Variable? No = infrequent REORG
• Variable? Yes = more frequent REORG (compression?)
• How frequently does the object change?
• Schedule REORG frequency appropriately
• Is downtime possible?
• Online vs. offline REORG
• Modify the REORG schedule as access patterns change.

38
A small country may have many machines,
but the people will have no use for them…
-Lao Tzu
• “Doesn’t a DBMS like DB2 mean that we have to buy more
hardware to support it?” questioned the intern. “Only if you
plan not to work,” replied the Taoist DBA curtly.
• Lesson: The well-tuned DB2 environment will not necessitate
additional CPU power.
• Use DB2 as it was meant to be used and it will be efficient.
• Do not use DB2 like a flat file system – that means index the right
data, code the proper predicates, and join data as necessary.
• Do not read every row into the program and check the data like you
would a master file. (VSAM vs. DB2)
• Do not needlessly limit DB2 (e.g. only 5 indexes per table).
• Educate every DB2 user on proper SQL coding techniques.

39
In walking, just walk.
In sitting, just sit.
Above all, don’t wobble.
-Yun-Men
• The order entry system was down. The main table space
needed to be recovered. As the Taoist DBA focused on his
task his intern fidgeted, fretting about the managers milling
around his office. “Is the system up and running?” The Taoist
DBA presses <ENTER> and winks.
• Lesson: Focus and concentration save the day in stressful
situations; do not panic and avoid worrying about non-
essential things (e.g. other tasks, managers, etc.)
• Repeat past successes.
• Automate as much as possible.

40
Do that which consists in taking no action
and order will prevail.
-Lao Tzu
• Continuing to teach his intern, the Taoist DBA whispers
softly, “When all around you is in flux, sip your coffee and
contemplate the situation. Not every problem requires a
solution.”
• Lesson: Sometimes the proper course of action is to do
nothing. This can be difficult to endure.
• Some “problems” solve themselves.
(or perhaps the solution is worse than the problem)
Pure in heart, like uncut jade,
he cleared the muddy water
by leaving it alone.
-Lao Tzu

41
Learn when to stop and you
will meet with no danger.
-Lao Tzu
• “The users request that we cancel one of their long-running
jobs,” stated the intern. “And who will pay
double to undo that damage?” was the lone
question posed by the Taoist DBA.
• Lesson: Sometimes it is better to let a task
run to completion than to stop it and incur
the cost of backing out.
• Always issue COMMITs in your batch jobs.

42
Change Management
A lot of things can go
wrong to cause DB2
performance problems? I
am sure, though, that
there is more to learn.
The Taoist DBA
The Intern
You have learned much.
Consider though, the
caterpillar and the butterfly;
How can we plan for
such changes?

43
Through his experience,
the sage becomes aware that all things change
-Lao Tzu
• “The users want to change the data type of several columns,”
stated the intern. “The only constant is change,” chanted the
Taoist DBA.
• Lesson: Be prepared to support many different types of
change requests. Some will be simple, some complex. All
require careful planning to implement.
• Change management is not simple even with DB2 V8 and Online
Schema Change:
• What can change using ALTER? What cannot?
• Versions and performance
The difficult and the easy
complement each other.
-Lao Tzu

44
When considering any thing,
do not lose its opposite.
-Lao Tzu
• “So, all I have to do is drop the table and re-create it with the
new column in the middle?” asked the intern. “Yes, that is
all,” replied the Taoist DBA, shaking his head sarcastically.
• Lesson #1: Dropping an object drops all related objects and
authority. Understand the connectedness of all DB2 objects.
• Lesson #2: Changes may need to be undone; be ready. A
DBA must be ready to undo anything he does – and then redo
it again.
• Seriously consider a change management tool that will keep track of
changes for you and automate the process.
• Without such a tool you will need to manually track and
store your DROP and CREATE statements somehow.

45
This interaction of yin and yang is called
the Way, and the resulting creative process
is called change.
-I Ching
• Realization dawning upon him, the intern mutters “Dealing
with change seems like it will be a big part of my job.” With a
grin, the Taoist DBA replies, “You have no idea how
true that is.”
• Lesson: A DBA must be prepared to implement
changes to database structures, but also to react to
the changes made around the DBMS.
• Most performance problems are caused because something changed –
but finding out what changed can be a daunting task.

46
DBA Guidelines
Is there yet more wisdom
you can share with me?
The Taoist DBA
The Intern
That you are wise enough
to ask speaks volumes
about your progress…

47
Do not attempt to be a particular type of
person, but be many types simultaneously.
-Chuang Tzu
• When the intern balked at helping with a WebSphere problem
his Taoist mentor told him “When you say it is not your job,
soon it will not be your job.”
• Lesson: A good DBA must be a jack-of-all-trades. Expanding
your knowledge and sphere of influence is always a good
thing.

48
To know, yet to think that one does not know
is best; not to know, yet to think that one
knows will lead to difficulty.
-Lao Tzu
• “Oh, I’ve seen this problem before. All I have to do is to add
an index like before and…” said the intern excitedly. “To a
hammer all problems look like nails,” replied the Taoist DBA.
• Lesson: Do not rush to a solution. Take in all there is to learn
and though you should rely on your past experience, do not
force fit that experience to every problem.
• Every day is an opportunity to learn something new.
• Humility is a quality that DBAs would do well to exhibit.

49
One who excels in employing others humbles
himself before them…this is known as making
use of the efforts of others.
-Lao Tzu
• “I feel like I have to know everything,” complained the intern.
“Someone has to,” laughed the Taoist DBA.
• Lesson: The job of a DBA is complex and you cannot know
everything. Learn from others and use the knowledge of
others to succeed.
• Learn who knows what within your company.
• Other DBAs, network folks, system programmers, application
developers, transaction folks, web masters, etc.
• Network with other DBAs in your city/area.
• Network with others using the web, e-mail, etc.

50
Administrators who are wise
do not seek honors for themselves.
-Lao Tzu
• “Surely it must be annoying to answer the same question
multiple times a day?” said the intern, quite smugly.
“Hmmm,” said the Taoist DBA, “how many times have I
answered that?”
• Lesson: A DBA must be ready to assist without wanting to
bask in glory. Solving problems is more important than who
caused them, and even who solved them.
With wise administrators,
all can exist in unity
-Lao Tzu

51
My words are very easy to understand and
very easy to put into practice, yet no one can
understand them or put them into practice.
-Lao Tzu
Though the words of the sage are simple,
and his actions easily performed,
they are few among many,
who can speak or act as a sage.
-Lao Tzu
In this way he accomplishes
that which is required of him;
without dwelling upon it in any way,
he gives of his wisdom without display.
-Lao Tzu

52
Governing a large state
is like boiling a small fish.
-Lao Tzu
• Squinting confusedly at his mentor the intern mumbled “…
but a fish has nothing to do with my job.” The Taoist DBA
corrected his intern saying “There are lessons to be learned
everywhere and from everything.”
• Lesson: Don’t fix what isn’t broken…
• A small fish can be spoiled simply by handling it.
So can a well-tuned DB2 application.

53
People often fail on the verge of success.
By giving as much care to the end as to the
beginning, there will be few failures.
-Lao Tzu
• “I feel my confidence rising,” said the intern, “but I am
frustrated that I am not yet a master.” The Taoist
DBA winked and said “Then you know how
it feels.”
• Lesson: Persistence is a quality that all
successful DBAs possess. Perplexed by a
problem, it is always that next “thing”
that will solve it… and that is a good quality.

54
Go with the flow of things, and you
will find yourself at one with
the mysterious ways of the universe.
-Chuang Tzu
• “As a final lesson, let me tell you that you will learn to be
‘one with DB2’ as you apply your knowledge and these
lessons to the job at hand. Don’t panic, use your training, and
the Tao of DB2 will flow through you…” were the next to last
words the Taoist DBA had to say to the intern.

55
To retire when the task is accomplished
is the way of heaven.
-Lao Tzu
You are now on the path to
DB2 enlightenment… now
I can retire in peace.
Before you go,
what is your home
phone number?
Ahhh, truly you are now
ready… alas, I am unlisted.The Retired DBA
The Taoist Intern

58
The Tao of DB2
Session: B8
Craig S. Mullins
Mullins Consulting, Inc.
15 Coventry Court
Sugar Land, TX 77479
http://www.CraigSMullins.com
craig@craigsmullins.com

The Tao of DB2

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