Ora Perf Skillbldr1

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Copyright 2007-2007 Kyle Hailey. Distributed by www.skillbuilders.com.

SKILLBUILDERS

SkillBuilders Presents

Kyle Hailey (www.perfvision.com)Oracle Performance Tuning

Average Session Load

(ASL)The Golden Metric ?


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Who is Kyle Hailey 1990 Oracle

90 Oracle Unix support

92 Ported v6 onto Dec Ultrix

93 Oracle France 94 Gold Support Specialist

95 Performance Expert at Digital Europe

98 Kernel Development California

2000 Dot.Com

2001 Quest

2002 Oracle OEM 10g

2005 Embarcadero

2006 Independent

When not being being a Geek writing for the Oaktable etc

- photographer

- Just Married and new home owner in Portland

- and wonder how I missed the dot.com millions


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In this SessionThe Holy Grail of Performance : ASL

1. ASL : stethoscope for Database Health

Tap is a metric that taps directly into the heart of your DB Heart stopped - Hung? Beating very slow - Idle ? Beating fast - Heavily Loaded ?

2. ASL Components CPU Waits Time series

3. Maximum CPU as Yardstick To measure ASL against

OEM 10g ties it all together


4/84Copyright 2007-2007 Kyle Hailey. Distributed by www.skillbuilders.com.

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Goal of this Presentation

Simplify the data and empower the DBA

My goal is to cut out a lot of the unnecessaryinformation and extraneous data andhone in on the essential

When to act How hard to act



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Whats the Database Doing?

Your manager calls, its 2am, do you knowwhere your database is?

Blocked

Running ok Idle

I want a quick and easy way to see what the

database is doing



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Checking the Database

How do *you* check the Database Health?Routine Exams?

Statspack?

1300 lines of data Which lines

Once and hour

Automated Alerts? What do you set alerts on?

What if no alerts fire ? Are you ok?

Do alerts really tell you whats happening?



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Whats the Database Doing?!

Whip out the stethoscope

ASL



8Welcome to

The Cult of ASLOnce youve been initiated

there is no going back

For those of you who are already members, welcome back



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Average Session Load (ASL)

The Golden MetricPowerful

Multidimensional

Indispensable

Average load of sessions on the database

measured in number of sessions


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Core of 10g Performance Monitoring


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Performance Page


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Average Session Load (ASL)aka

Average Active Sessions (AAS?)

OEM 10g GraphsSession Load

I often refer to it this way

Centi-seconds per second (or secs/sec) In the dark ages, before OEM 10g, waits were

often measured as Centi-secs per sec


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ASL Average Session LoadAverage

over 15 secs in OEM 10g

Represents Load

Active Sessions Only

Active sessions put load the database

Inactive Sessions dont put load

Except for memory usage


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ASL : sources

1. Manually

v$system_event v$sysstat

2. Statspack some calculations

3. OEM 10g

4. ASHRPT


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ASL Calculation

ASL = DB TIME / Elapsed Time

DB Time (DBT) = sum over all sessions of time spent in acall. A call could be

executing SQL

background work

DBWR writing blocks

LGWR writing redo

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DB Time

DB Time (DBT) = sum active session time

DB TIME (10g) =

DB TIME =

select value from v$sysstat

where name = DB time;

select value from v$sysstat

where name = DB time;DB time

Select sum(time_waited) from v$system_eventwhere event not in ( ... idle events );+Select value from v$sysstat

where name = CPU used by this session;

Select sum(time_waited) from v$system_eventwhere event not in ( ... idle events );+Select value from v$sysstat

where name = CPU used by this session;

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1. ASL Manually

Data 10g, easy DBTime = V$sysstat DB time

9i ( 7 to 11 actually), DBTime = V$system_event

Sum wait times

Non-idle waits

V$sysstat

CPU used by this session

ASL= DBTime/elapsed time

Produces Session time / elapsed time

Session cent-secs/sec

Session secs/ sec

Avg Session Load (ASL)

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2. Statspack: Calculating ASL Look for

Top 5 Timed Events

Elapsed Time

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Statspack: Cheat Sheet

Install

Connect as SYSDBA@?/rdbms/admin/spcreate.sql

Run

Exec statspack.snap;

Generate Reports

@?/rdbms/admin/spreport.sql

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Statspack Output

Trusty statspack report

Elapased Time

Check Top 5 Timed Events

Start at line 52 ofStart at line 52 of

about 1300!about 1300!

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St t k El d Ti


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Statspack Elapsed Time

STATSPACK report for

DB Name DB Id Instance Inst Num Release RAC Host

------- ----------- -------- -------- ---------- --- -------

LABSF03 1420044432 labsf03 1 10.1.0.2.0 NO labsfr

Snap Id Snap Time Sessions Curs/Sess--------- ------------------ -------- ---------

Begin Snap: 1 03-Apr-06 12:34:06 18 5.6

End Snap: 2 03-Apr-06 12:34:36 18 4.8

Elapsed: 1.00 (mins)

STATSPACK report for

DB Name DB Id Instance Inst Num Release RAC Host

------- ----------- -------- -------- ---------- --- -------

LABSF03 1420044432 labsf03 1 10.1.0.2.0 NO labsfr

Snap Id Snap Time Sessions Curs/Sess--------- ------------------ -------- ---------

Begin Snap: 1 03-Apr-06 12:34:06 18 5.6

End Snap: 2 03-Apr-06 12:34:36 18 4.8

Elapsed: 1.00 (mins)

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Statspack: Top 5 Timed Events

Look at Top 5 Timed Events

Top 5 Timed Events

~~~~~~~~~~~~~~~~~~ % Total

Event Waits Time (s) Call Time--------------------- --------- --------- -------

buffer busy waits 2,748 250 78.72

CPU time 32 10.16

free buffer waits 1,588 15 4.63write complete waits 10 8 2.51

log buffer space 306 5 1.51

Top 5 Timed EventsTop 5 Timed Events

~~~~~~~~~~~~~~~~~~ % Total~~~~~~~~~~~~~~~~~~ % Total

Event Waits Time (s) Call TimeEvent Waits Time (s) Call Time------------------------------------------ ------------------ ------------------ --------------

buffer busy waits 2,748 250 78.72 buffer busy waits 2,748 250 78.72

CPU time 32 10.16CPU time 32 10.16

free buffer waits 1,588 15 4.63free buffer waits 1,588 15 4.63

write complete waits 10 8 2.51write complete waits 10 8 2.51

log buffer space 306 5 1.51log buffer space 306 5 1.51

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Example

CPU + WAITSCPU = 32

WAITS = 250 + 15 + 8 + 5

= 278 secs

Elapsed Time= 60 secs

(32 + 278) secs / 60 secs= 5.1 Average Session Load

Top 5 Timed Events

Event Time (s)

----------------- ----- buffer busy waits 250

CPU time 32

free buffer waits 15

write complete waits 8

log buffer space 5

Top 5 Timed EventsTop 5 Timed Events

Event Time (s)Event Time (s)

---------------------------------- ---------- buffer busy waits 250 buffer busy waits 250

CPU time 32CPU time 32

free buffer waits 15free buffer waits 15

write complete waits 8write complete waits 8

log buffer spacelog buffer space 55

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S O


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3. ASL in OEM DB Home Page

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4 ASHRPT


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4. ASHRPT

?@/rdbms/admin/ashrpt.sql

Top User Events DB/Inst: TESTDB/testdb (Apr 21 12:00 to 12:05)

Avg Active

Event Class % Activity Sessions

--------------------------- ----------- ---------- ----------

CPU + Wait for CPU CPU 67.98 8.42

enq: TX - row lock co Application 23.98 2.97

buffer busy waits Concurrency 4.66 0.58

latch: cache buffers chai Concurrency 2.26 0.28

Top User EventsTop User Events DB/Inst: TESTDB/DB/Inst: TESTDB/testdbtestdb (Apr 21 12:00 to 12:05)(Apr 21 12:00 to 12:05)

AvgAvgActiveActive

EventEvent ClassClass % Activity% Activity SessionsSessions------------------------------------------------------ ---------------------- -------------------- --------------------

CPU + Wait for CPUCPU + Wait for CPU CPUCPU 67.9867.98 8.428.42

enqenq: TX: TX -- row lock corow lock co ApplicationApplication 23.9823.98 2.972.97

buffer busy waitsbuffer busy waits ConcurrencyConcurrency 4.664.66 0.580.58latch: cache bufferslatch: cache buffers chaichai ConcurrencyConcurrency 2.262.26 0.280.28

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Got ASL, Now What ?Need one more item: CPU Count

# of CPUs available on System

Shared with other applications ? difficultOn dual & quad cores, lower the CPU count

Represents max active sessions doing work

A value above CPU represents some bottleneck

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CPU t OEM DB H P


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CPU count, OEM DB Home Page

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CPU Count, OEM Perf Page

CPU CountCPU Count

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Available CPU init.oraStatspack 10g shows # of CPUS

Statspack 9i # of CPUs missing:

SQLPLUS> show parameters cpu_count

NAME VALUE

------------------ ----------cpu_count 2

SQLPLUS> show parameters cpu_count

NAME VALUE

------------------ ----------cpu_count 2


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ASL F l


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ASL Formulas

Use CPU count as yardstick:

< 1

Database is not blocked ASL ~= 0

Database basically idle

ASL < # of CPUsCPU available

Database is probably not blocked

ASL > # of CPUsCould have performance problems

ASL >> # of CPUSThere is a bottleneck

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Available CPU vs ASL


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Available CPU vs ASL

ASL = 5.1ASL = 5.1

# of CPU = 2# of CPU = 2

ASL far above available CPU => problem

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Going Farther with ASLASL can tell you a lot

But its components tell you much more

To go farther need the components of ASL

CPU How many CPUs (max CPU available)

Wait

Which waits

Value over time

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EM DB Home Page


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EM DB Home Page

35OEM 10g Perf Pages


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OEM 10g Perf PagesDB HomeDB Home

PerformancePerformance

ASL Point in TimeASL Point in Time

ASL over TimeASL over Time

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Performance Page


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Performance Page

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Performance Page


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Performance Page

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ASL P f P


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ASL Performance Page

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OEM 10 ASL


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OEM 10g - ASL

ASL is the top of the curveASL is the top of the curve

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1.91.9 22

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OEM 10 CPU


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OEM 10g - CPU

CPU UsageCPU Usage

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OEM 10 W it


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OEM 10g - Waits

WaitsWaits

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OEM 10 CPU W it


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OEM 10g CPU vs Wait

WaitsWaits

CPUCPU

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OEM 10 M CPU


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OEM 10g Max CPU

Maximum Possible CPUMaximum Possible CPU

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OEM 10g Zoom In


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OEM 10g Zoom-In

CPU + WAIT

Available CPU

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OEM 10g get to work !


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OEM 10g get to work !

LooksLooksOKOK

But But

RelaxRelax Get to Work!Get to Work!

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Alternative ASL Calculations

ASL = DB TIME / Elapsed Time

But there is another wayBut there is another way

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ASL b d ASH


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ASL based on ASH

ASH - Active Session History

v$active_session_history

Formula

Count active sessions over 15 seconds

Divided by # of samples in 15 seconds= Average Session Load

A statistical approximation, but surprisingly close

ASH data source empowers drilldown into thecauses of bottlenecks

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2 ASL from ASH


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2. ASL from ASH

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4433

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55

4433

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ASHASH

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t0t0 tntn

11

t0t0--nn

active sessions(ti)nn

00ASL =ASL = // nn

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Two Sources comparison


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Two Sources comparison

1. v$system_event & v$sysstat

Indirect

Accurate

Lags (especially CPU)

Limits analysis

2. v$active_session_history

Direct

Real time Approximation

Allows drilldowns



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DB HomeDB Home


Top ActivityTop Activity

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Same Chart butSame Chart but

calculated differentlycalculated differently

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1. ASL Performance PageDB HomeDB Home


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v$v$sysstatsysstat

DB HomeDB Home



v$system_eventv$system_event

ASL = DBT /ASL = DBT / TimeTime

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2 ASL Top Activity Page


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2. ASL Top Activity Page

v$active_session_historyv$active_session_history

active sessions(ti)nn

00ASL =ASL =

DB HomeDB Home



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Samples VS Counters


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Samples VS Counters

CountersCounters

SamplesSamples

Slight LagsSlight Lags

v$system_eventv$system_event

v$active_session_historyv$active_session_history

54The Power ASH gives ASLDB HDB H


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DB HomeDB Home



ASHASH

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ASH in OEM


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Top Activity givesTop Activity gives

more informationmore information

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Top Activity : Based on ASH


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Top Activity : Based on ASH

missingmissing

ThanksThanks

ToTo

ASHASH

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Top Activity : ASH Dimensions


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Top Activity : ASH Dimensions

58ASL %Session Time Issue


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Shown in % DB TimeShown in % DB Time

Missing % Session TimeMissing % Session Time

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Top Activity: ASH Sessions


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Many Users ActiveMany Users Active

On Performance Page, no way to tell how many usersOn Performance Page, no way to tell how many users

But Top Activity Page fixes thatBut Top Activity Page fixes that

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Top Activity: ASH Sessions


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Two Users ActiveTwo Users Active

61OEM 10g Perf PagesDB HomeDB Home


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DB HomeDB Home



SQLSQLSessionSession



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SQLSQLSessionSession

63Session : ASH Activity


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64SQL : ASH Activity


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Getting the Most out of ASL


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Need to know the Systems Profile

What your application is like? Data Warehouse

OLTP Typical load

Once you get to know it you can see anomalies

Is ASL near 0 when it should be higher Is that Data Warehouse query running normal

Do you know what it looks like?

Is there an unusual bottleneck

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Knowing your DB Profile


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When to tune?General rules of Thumb

Waits >> CPU

CPU > Max CPU

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Waits > CPU

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CPU > Max CPU


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Idle DatabaseValue of proving the database is Idle

Its the Databases FaultHow many times do you hear that?

Database IdleNo load on database

Database performance is fine Under utilized

Problem lies elsewhere

Saved me time and stress many times

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Idle Database Perf Page


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Idle Database Top Activity


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Harnessing ASL


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Statspack lacking

OEM 10g Best tool 10g (or 11) only

Need licences

Third Party Tools Some good products

Generally as expensive as OEM

Ashmon OEM-lite Free

Any version with S-ASH

Limited analysis

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Statspack

Free and any version

Needs numerical massaging

Lacking detailed SQL and Session info

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OEM 10g


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Clearest, easiest, most powerful Overview

Load chart - ASL

Breakdown Top SQL and Session

Or Service, Module, Action, Objects, Files

Drill downs

SQL Session

Plus ADDM Automatic Database Diagnostics Monitor

SQL Advisor SQL tuning advice

DRAWBACK 10g (or 11) and need license

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OEM 10g Perf PagesDB HomeDB Home


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SessionSession SQLSQL

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AlternativesThird Party tools

Quest Performance Analyzer

Symantec I3

Confio Ignite

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ASHMON a free OEM-lite http://perfvision.com/ashmon.php

Windows application

Monitors Oracle 10g or 11

Show Top Activity page from OEM

Note: Can be used on any version of Oraclewith performance repository available onhttp://perfvision.com/sash.php

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CPU > Max CPU


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Radical Change in Profile


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Going Further Wait AnalysisIf ASL identifies Wait Bottlenecks

Use OEM 10gAutomatic Diagnostic Database Monitor (ADDM)

Oracle Wait Interfaceby R Shee and K Deshpande

Wait Interface Class

Detail explanation, analysis and solutions to thetop 30 wait events (98% of all waits encountered)

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Where Can You Learn MoreOracle 10g Advanced Performance Tuning

ClassWith Kyle Hailey and SkillBuilders

2 Day Class

Offsite or onsite

Registration

www.skillbuilders.comGary Belke at 1-888-803-5607

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Oracle 10g Advanced


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Performance Tuning Class Learn new 10g performance and diagnostic tools

Understand the 10g Enterprise ManagerPerformance page

ASL, AWR, ADDM

Advanced level of detail Collection, Aggregation, Display, Analyze

Top 30 wait events

ASH

Conquer your database woes!

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In summary ASL is simple and Powerful

ASLs components are even more powerful CPU

WAIT

Value over Time Use # of CPUs as a yardstick

Know your application load profile to see anomalies

Monitor ASL with OEM 10g, Ashmon or third partytools

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