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Oracle8:
Performance Tuning
| Exam
Facts: 1Z0-014 |
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|
Passing
Score:
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48,
79% |
| Test
Type: |
Proctored |
| Format: |
61
multiple choice questions |
| Time
Allotted: |
90
minutes |
| Certifications: |
Oracle8
Database Administrator |
| Study
Brief: |
Online
format |
| Feedback: |
Oracle
Certified Professional Forum |
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| Topics
To Know |
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| By
Don Farland, Oraclenotes.com |
Are you ready? Ask yourself this question carefully, because this test will certainly
answer it for you. This exam will truly test your knowledge of Oracle database
tuning. The questions will be vague, seemingly incomplete, and in some cases
dangerously close to "over-generalizing" tuning guidelines. They are
certainly not kidding when they want you to pick the BEST answer. Eliminate the
obviously incorrect answers and go from there.
This
test will grill you on tuning memory structures, SQL,
disk I/O, storage, sorts, rollback segments, locks,
latches, using performance monitoring tools, and Oracle
Expert. Seem like a lot? It is!
Not
since the DBA exam have I seen this many questions
about performance views. I'd list all the relevant
ones here, but there are far too many. Review the Instructor
Led Training materials or the OCP Study Guide from
Oracle Press to find out what each one does and what
fields are important to tuning an Oracle instance.
After the dynamic performance views, Report.txt , generated
from utlbstat and utlestat, is another heavily covered
topic. Know what information is available in this report
and how to generate it.
Expect
a couple of questions about the OEM tools related to
performance tuning, primarily those available in the
Tuning Pack. Expect a lot of questions on tuning memory
structures like the Shared Pool, Buffer Cache, and
Log Buffer. The most important thing to know about
these structures is how to differentiate acceptable
and unacceptable performance. While this is true with
all the other components of a database system, expect
to get numerous questions on making this determination.
However, be ready for a number of questions on how
to remedy the situation. In all, this general area
of tuning was represented with 16 questions on my exam,
I would expect a similar number when you sit for this
exam.
I
went into this exam expecting disk I/O and block storage
to get a lot of attention and I was right. Ten questions
on my exam related to one of these two subjects. Fortunately,
they weren't that difficult. Make certain you know
how PCTFREE, PCTUSED, freelist contention, chaining,
and dynamic extent allocation all affect database performance
and how to avoid and resolve these problems.
Expect
five questions apiece for tuning rollback segments
and sort operations. Make certain you know how to adequately
size rollbacks for OLTP, DSS, and batch processing
environments. As for tuning sort operations, make sure
you know how to determine sort requirements and effectively
size sort parameters, especially sort_area_size.
My
Performance Tuning instructor and "Oracle God",
Bill Sutton, described SQL Tuning as simply, "Touch
as few blocks as possible." This statement accurately
describes the goal of SQL tuning. The less data you
have to "touch" the faster the statement
executes. Know how indexes, case conventions, keep/recycle
pools, caching, and pinning large objects can help
you achieve that simple, yet accurate statement.
As
for tuning the operating system, "Avoid swapping
and paging". Believe it or not that simple axiom
will help you with this topic as well. Allocate too
much system memory for the SGA and you may actually
make the situation worse. Also, make sure you are aware
of the implications of sizing DB_BLOCK_SIZE (smaller
than) or (to a value that is not a multiple of) the
OS block size.
Tuning
locks and latches will probably garner six or seven
questions on your exam. If you know how to resolve
redo copy latch contention as well as how deadlocks
are resolved then chances are you'll get through this
area fairly well. Watch out for a question or two about
LRU latches and row versus table level locking too.
The
rest of this exam will ask you questions like, "What
should you tune first?" or "What best characterizes
how you would tune an OLTP application?" Watch
out for these questions. Many of them make sweeping
generalizations about OLTP, DSS, or Hybrid applications
that are dangerously close to being wrong. I don't
think I can tell you how to best approach these questions.
These questions make the differences between OLTP and
DSS seem like they are always black and white. Which
in the real world is simply not the case. Read these
questions very carefully and try to identify the answer
that is the closest to the truth.
Good
Luck!
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