Checkpoint tuning

Hi All,
Can any body tell me the importance of ARCHIVE_LAG_TARGET and FAST_START_MTTR_TARGET parameters. I mean what are the scenarios in which we will use them.
If any doc available plz provide me the link.

If any doc available plz provide me the link.http://tahiti.oracle.com
check out Reference Manual
Edited by: sb92075 on Jan 17, 2011 11:21 AM

Similar Messages

Automatic Checkpoint Tuning in Oracle 10g

Hi ,
How to confirm if the database has been configured for automatic checkpoint tuning...????
Many thanks...
Sim

The log_checkpoint_timeout (default 1800) gives Oracle a time-based target, and the log_checkpoint_interval (default 0, meaning the action is based on the size of the current redo log file) give Oracle a 'volume-based' target.
The target affects the rate at which the database writer writes dirty blocks to disk. Every three seconds the database writer wakes up and checks the tail-end of the checkpoint queue and writes out any blocks that were attached to the queue too far in the past.
In this context, "too far in the past" means either "more seconds in the past than the[i] log_checkpoint timeout" or "made dirty by a change described in a redo block more than log_checkpoint_interval blocks back from the current block".
If you set fast_start_mttr_target to a non-zero number of seconds then Oracle tries to treat that as a request to write out dirty blocks sufficiently rapidly that crash recovery will take no more than that number of seconds. In effect this makes Oracle change the internal value of log_checkpoint_interval and log_checkpoint_timeout dynamically every few seconds.
Recoverty requires Oracle to apply the redo log from a known point - which means reading and applying a certain amount of redo to a number of "out of synch" blocks that have to be read from disk. So the fast_start_mttr_target code is constantly calculating how much redo would have to be read and applied, and how many data blocks would have to be read and fixed - and writing dirty blocks fast enough to make it possible to do that work within the given time limit.
Setting the parameter to zero is (as it is with many numerical parameters) equivalent to not setting it at all. If you try to set the parameter to a very small value (say 30 seconds) you may end up finding lots of messages in your alert log saying something like: "I can't honour your request to recover in 30 seconds, the best I can do is XXX".
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk

Automatic checkpoint tuning in 10g?

Does anyone have an idea with the following sentence?
Automatic checkpoint tuning is enabled when FAST_START_MTTR_TARGET is not explicitly set to zero.
I think the incremental checkpoint event was introduced in 9i...But I saw this automatic checkpoint tuning feature in the 10g OTN doc. what's new?
Anyway!! we need to set this parameter with a non-zero value to use the incremental checkpoint event though.

hi,
Since Oracle 9i FAST_START_MTTR_TARGET parameter is the preferred method
of tuning incremental checkpoint target. FAST_START_MTTR_TARGET enables you to specify the number of seconds the database takes to perform crash recovery of a single instance. Based on internal statistics, incremental checkpoint
automatically adjusts the checkpoint target to meet the requirement of
FAST_START_MTTR_TARGET.
V$INSTANCE_RECOVERY.ESTIMATED_MTTR shows the current estimated mean time to
recover (MTTR) in seconds. This value is shown even if FAST_START_MTTR_TARGET
is not specified.
V$INSTANCE_RECOVERY.TARGET_MTTR shows the effective MTTR target in seconds
enforced by the system.
V$MTTR_TARGET_ADVICE shows the number of I/Os resulted by the current workload
under the current MTTR setting and the estimated number of I/Os that would be
resulted by the current workload under other MTTR settings.
so I would recommend you run this sql to find out what the system thinks your MTTR_TARGET should be.
If FAST_START_MTTR_TARGET is specified, LOG_CHECKPOINT_INTERVAL should not
be set or set to 0.
rgds
alan

Checkpoint not complete

Hi
I am getting this error in my alter.log file.Due to this error our performance is reduced. can you please tell me what are the steps i need to take to solve this issue in oracle 9.2.0.7 and 10.2.0.2 environment?
Thanks.
Regards,
RJ.

Hi, i think that your problem is about the redo logs, you will must tunning the size and location disk ( fast disk) of your redelogs.
You can see the next documetation on Metalink site.
Note:147468.1 Checkpoint Tuning and Troubleshooting Guide
Regards.
Luck
Have a good day.

"Checkpoint not complete" hangs!

Hi everyone;
I see "Checkpoint not complete" in the alertlog but normally oracle just waits seconds then checkpoints and go on... But the problem is, database sometimes hangs with this message for minutes and never respond until i checkpoint manually.
I made the necessary changes to avoid "Checkpoint not complete" message. Number of Redolog groups was increased, redolog size was increased, 5 dbwr was configured.
But the real problem is not the message, oracle cannot go over this message and hangs!!
10.2.0.1.0 - on hp-ux 11.31
Thanks for your help...
Edited by: emre baransel on Sep 18, 2009 10:27 AM

emre baransel wrote:
Hi everyone;
I see "Checkpoint not complete" in the alertlog but normally oracle just waits seconds then checkpoints and go on... But the problem is, database sometimes hangs with this message for minutes and never respond until i checkpoint manually.Oracle hangs until released the checkpoint, this is an expected behaviour to be keep data consistency :
http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/waitevents003.htm#sthref3113
Please, check the alert log file to see the time between redolog switch. Check if you have not I/O slowness on your hard drive.
I would advise the reading of Metalink note
Checkpoint Tuning and Troubleshooting Guide*
Doc ID: 147468.1*
Nicolas.

"checkpoint not complete" in alert log file.

Hi, all.
I have got a message of "Checkpoint not complete" in alert log file.
Thread 2 advanced to log sequence 531
Current log# 7 seq# 531 mem# 0: \\.\REDO231
Current log# 7 seq# 531 mem# 1: \\.\REDO232
Thread 2 cannot allocate new log, sequence 532
Checkpoint not complete
Current log# 7 seq# 531 mem# 0: \\.\REDO231
Current log# 7 seq# 531 mem# 1: \\.\REDO232
I searched "Checkpoint not complete" issue in this forum.
As solutions,
1. add more redo log groups
2. increase the size of redo log
3. check I/O contention
4. set LOG_CHECKPOINT_INTERVAL, LOG_CHECKPOINT_TIMEOUT or
FAST_START_MTTR_TARGET
I think No.4 is the possible first approach in our environment.
I think No.1 and No2 are not the ploblems in our environment.
I ask the above issue oracle support center, but
I was told that "if you are not getting this message frequently, you do not need to worry about it" from an oracle engineer.
Is this true?? If I am not getting this message frequently, there is no problem
in terms of database integrity, consistency, and performance?
I will be waiting for your advice and experience in real life.
Thanks and Regards.

Redo Log Tuning Advisory and Automatic Checkpoint Tuning are new features introduced in Oracle 10G, if you are on 10g you may benefit from these features.
The size of the redo log files can influence performance, because the behavior of the database writer and archiver processes depend on the redo log sizes. Generally, larger redo log files provide better performance, however it must balanced out with the expected recovery time. Undersized log files increase checkpoint activity and increase CPU usage. As rule of thumb switching logs at most once every fifteen minutes.
Checkpoint frequency is affected by several factors, including log file size and the setting of the FAST_START_MTTR_TARGET initialization parameter. If the FAST_START_MTTR_TARGET parameter is set to limit the instance recovery time, Oracle automatically tries to checkpoint as frequently as necessary. Under this condition, the size of the log files should be large enough to avoid additional checkpointing due to under sized log files.
The redo logfile sizing advisory is specified by column optimal_logfile_size of v$instance_recovery. This feature require setting the parameter "fast_start_mttr_target" for the advisory to take effect and populate the column optimal_logfile_size.
Also you can obtain redo sizing advice on the Redo Log Groups page of Oracle Enterprise Manager Database Control.
To enable automatic checkpoint tuning, unset FAST_START_MTTR_TARGET or set it to a nonzero value(This is measured in seconds and by default, this feature is not enabled, because FAST_START_MTTR_TARGET has a default value of 0). If you set this parameter to zero this feature will be disabled. When you enable fast-start checkpointing, remove or disable(set to 0) the following initialization parameters:
- LOG_CHECKPOINT_INTERVAL
- LOG_CHECKPOINT_TIMEOUT
- FAST_START_IO_TARGET
Enabling fast-start checkpointing can be done statically using the initialization files or dynamically using -
SQL> alter system set FAST_START_MTTR_TARGET=10;
Best regards.

What is the consequence of disable fast-start checkpointing?

What is the consequence of disable fast-start checkpointing ( or set fast_start_mttr_target=0 ) ?

If you mean what happens if you setfast_start_mttr_target to zero, then in my opinion not much. It just means the entire online redo log will need to be read and potentially applied on crash recovery.
I do not see this as an issue for most databases as in my experience our system can perform crash recovery quick enough with the value at zero.
However, there is generally no need to set this parameter to zero unless you IO system is at maximum performance since the parameter does increase IO load a bit, but only a bit. Ref:
Automatic Checkpoint Tuning in 10g #265831.1
HTH -- Mark D Powell --

Checkpoint frequency when the database is open.

Dear All,
I am facing a lot of problem with some checkpoint parameters.
FAST_START_IO_TARGET = value in what?
LOG_CHECKPOINT_INTERVAL = value in no. of OS blocks
LOG_CHECKPOINT_TIMEOUT = value in seconds
Almost every places (Documentation and our books) it is
mentioned that they are used only for instance recovery. Is it
true? If so, then we don't have any way to force checkpoint to
occur frequently when the database is running. Is there any way?
I think the last two parameters work also when the database is
running.
If multiple parameters used for checkpoint will oracle use FIFO
system or it will choose only the most aggressive parameter?
Please see the Backup&Recovery slide 2-12. It show the case of
instance recovery. As the most aggressive parameter
LOG_CHECKPOINT_INTERVAL is issuing checkpoint first. Will there
be any checkpoint at "C" or checkpoint will occur at any other
point again set by LOG_CHECKPOINT_INTERVAL ?
Please help me to solve this problem.
Have a nice time,
Tarek
BASE Ltd, Dhaka

There is an execellent document available on metalink explaining
the details of the checkpoint mechanism and how to tune it.
Document's name is "Checkpoint Tuning and Troubleshooting Guide",
Doc Id is 147468.1.
That document explains the parameters you ask about and
tells you a helluva lot about checkpoints and how to get
them to do just as you want.
If you do not have access to Metalink, drop me a mail
notice at [email protected], and I'll send you
a copy via email.
Hope that helps.
All the best
Michael

Nor more Checkpoints at every log-switch in 10.2 ?

Hi,
i working with Oracle about 12 years but i havn´t seen this before:
REM There is no work/application in the database now:
select group#,status from v$log;
GROUP# STATUS
1 CURRENT
2 ACTIVE
4 ACTIVE
5 ACTIVE
6 ACTIVE
First as i know only one or two (for a short time) shiould be active.
OK wait 90 seconds:
SQL> /
GROUP# STATUS
1 CURRENT
2 ACTIVE
4 ACTIVE
5 ACTIVE
6 ACTIVE
Try a log switch:
alter system switch logfile;
SQL> select group#,status from v$log;
GROUP# STATUS
1 ACTIVE
2 CURRENT
4 ACTIVE
5 ACTIVE
6 ACTIVE
How can i now drop one of the redo-logs ?
=> Solution:
alter system checkpoint;
select group#,status from v$log;
GROUP# STATUS
1 INACTIVE
2 CURRENT
4 INACTIVE
5 INACTIVE
6 INACTIVE
Does anybody know what Oracle changed here ?
Thanks in advance
Marco

hi,
welcome to Oracle10g:
show paramater FAST_START_MTTR_TARGET
if it is '0', then auto-checking-pointing is DISABLED, this happens to be the default on Oracle XE (under review)
By default, Oracle 10g supports automatic checkpoint tuning by making the best effort to write out SGA buffer cache dirty buffers w/o impacting the throughput of runtime physical I/O, thus achieving reasonable crash recovery time.
Setting the FAST_START_MTTR_TARGET parameter to a non-zero value or not setting this parameter enables automatic checkpoint tuning. The STATISTICS_LEVEL must be TYPICAL OR ALL. After a period of time, see V$MTTR_TARGET_ADVICE for various value for this parameter.

Processes in v$process which do not exist in v$session(help)!!

Hi, all.
The database is 2 node RAC database (10.2.0.2.0)
on 32 bit windows 2003 EE SP1.
Our database is suffering "CKPT hang" from time to time.
I checked v$process and v$session on both node by the following sql.
select addr,pid,spid,username, program
from v$process
where addr not in (select paddr from v$session)
ADDR     PID     SPID     USERNAME     PROGRAM
56E2     1               PSEUDO
56E2     18     3984     SYSTEM     ORACLE.EXE (D000)
56E2     19     4020     SYSTEM     ORACLE.EXE (S000)
56E2     27     3176     SYSTEM     ORACLE.EXE (PZ99)
56E3     39     2296     SYSTEM     ORACLE.EXE (PZ97)
●select * from v$px_process
SERVER_NAME     STATUS     PID     SPID     SID     SERIAL#
PZ97     AVAILABLE     39     2296
PZ99     AVAILABLE     27     3176
●select * from V$PX_SESSION
--> no rows
●select slave_name,status from v$pq_slave
SLAVE_NAME     STATUS
PZ97     IDLE
PZ99     IDLE
I found the above processes which do not exist in v$session.
Is this normal??
Thanks and Regards.
Message was edited by:
user507290

Hi,
>>I can see incomplete checkpoint message in alert log files.
This message indicates that Oracle wants to reuse a redo log file, but the current checkpoint position is still in that log. In this case, Oracle must wait until the checkpoint position passes that log. In fact, the "checkpoint not complete" messages are generated because the logs are switching so fast that the checkpoint associated with the log switch isn't terminated. Oracle stops processing until the checkpoint completes successfully.
In this case, normally you need to increase the size of the redo logs or add more redo log groups. Take a look on http://www.dbazine.com/oracle/or-articles/foot2
Now, as you said that the current redo size is 2 GB, how frequently redo log switch's occurs in the database ? See the SQL's below:
Log Switching Distribution
select to_char(first_time,'DD/MM/YYYY') day,
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'00',1,0)),'999') "00",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'01',1,0)),'999') "01",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'02',1,0)),'999') "02",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'03',1,0)),'999') "03",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'04',1,0)),'999') "04",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'05',1,0)),'999') "05",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'06',1,0)),'999') "06",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'07',1,0)),'999') "07",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'08',1,0)),'999') "08",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'09',1,0)),'999') "09",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'10',1,0)),'999') "10",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'11',1,0)),'999') "11",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'12',1,0)),'999') "12",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'13',1,0)),'999') "13",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'14',1,0)),'999') "14",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'15',1,0)),'999') "15",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'16',1,0)),'999') "16",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'17',1,0)),'999') "17",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'18',1,0)),'999') "18",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'19',1,0)),'999') "19",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'20',1,0)),'999') "20",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'21',1,0)),'999') "21",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'22',1,0)),'999') "22",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'23',1,0)),'999') "23",
sum(1) "TOTAL_IN_DAY"
from v$log_history
group by to_char(first_time,'DD/MM/YYYY')
order by to_date(day);
Average Switch Time
select to_char(first_time,'DD/MM/YYYY HH24')||':00:00' "Time",
count(*) "Nbswitch",
trunc(60/count(*),1) "Average switch time(minutes)",
count(*)*rsize "EstimateSize"
from v$log_history, (select sum(bytes/1024/1024)/count(*) rsize from v$log)
group by to_char(first_time,'DD/MM/YYYY HH24'),rsize
order by to_date(to_char(first_time,'DD/MM/YYYY HH24'), 'DD/MM/YYYY
HH24')desc;In addition, If you have access on Oracle Metalink, see the Note:147468.1 about Checkpoint Tuning and Troubleshooting Guide.
Cheers

Oracle Performance tunning genral question

Hi,
Below is the list of Areas of Oracle db for which tunning activities are done. You are invited to comment to it weather this is complete list or need some addition or deletion. As I'm learning PT for Oracle now a days, therefore I want to expand my knowledge by sharing what I'm learning and what I need to learn.
So comment with Open hearts on it. Espically from experts and Gurus.
Here is the List
1-Planning for Performance, include Storage consideration( Weather it is SAN, NAS, DAS), Network planning and host OS planning with proper configuration for running Oracle.
2-Database desining (Not under-Normalized and not Over-Normalized with proper usage of Indexes, views and Stored Procedures)
3- Instance tunning (Memory structure + B.g Processes)
4- Session tunning.
5- Segment Space tunning.
6- SQL tunning.
This is what uptill what I've learned. If it needs addition kindly tell me what are these. Please also provide me links(good and precise one) for PT tutorials on web.Also note that I'm discussing this w.r.t Single instance non-rac db.
Looking for Good sugessions
Regards,
Abbasi

Hello,
This is the oracle course contents:
Contents
Preface
1 Introduction
Course Objectives 1-2
Organization 1-3
Agenda 1-4
What Is Not Included 1-6
Who Tunes? 1-7
What Does the DBA Tune? 1-8
How to Tune 1-10
Tuning Methodology 1-11
Effective Tuning Goals 1-13
General Tuning Session 1-15
Summary 1-17
2 Basic Tuning Tools
Objectives 2-2
Performance Tuning Diagnostics 2-3
Performance Tuning Tools 2-4
Tuning Objectives 2-5
Top Wait Events 2-6
DB Time 2-7
CPU and Wait Time Tuning Dimensions 2-8
Time Model: Overview 2-9
Time Model Statistics Hierarchy 2-10
Time Model Example 2-12
Dynamic Performance Views 2-13
Dynamic Performance Views: Usage Examples 2-14
Dynamic Performance Views: Considerations 2-15
Statistic Levels 2-16
Statistics and Wait Events 2-18
System Statistic Classes 2-19
Displaying Statistics 2-20
Displaying SGA Statistics 2-22
Wait Events 2-23
Using the V$EVENT_NAME View 2-24
Wait Classes 2-25
Displaying Wait Event Statistics 2-26
Oracle Internal & Oracle Academy Use Only
iv
Commonly Observed Wait Events 2-28
Using the V$SESSION_WAIT View 2-29
Precision of System Statistics 2-31
Using Features of the Packs 2-32
Accessing the Database Home Page 2-34
Enterprise Manager Performance Pages 2-35
Viewing the Alert Log 2-37
Using Alert Log Information as an Aid in Tuning 2-38
User Trace Files 2-40
Background Processes Trace Files 2-41
Summary 2-42
Practice 2 Overview: Using Basic Tools 2-43
3 Using Automatic Workload Repository
Objectives 3-2
Automatic Workload Repository: Overview 3-3
Automatic Workload Repository Data 3-4
Workload Repository 3-5
Database Control and AWR 3-6
AWR Snapshot Purging Policy 3-7
AWR Snapshot Settings 3-8
Manual AWR Snapshots 3-9
Managing Snapshots with PL/SQL 3-10
Generating AWR Reports in EM 3-11
Generating AWR Reports in SQL*Plus 3-12
Reading the AWR Report 3-13
Snapshots and Periods Comparisons 3-14
Compare Periods: Benefits 3-15
Compare Periods: Results 3-16
Compare Periods: Report 3-17
Compare Periods: Load Profile 3-18
Compare Periods: Top Events 3-19
Summary 3-20
Practice 3 Overview: Using AWR-Based Tools 3-21
4 Defining Problems
Objectives 4-2
Defining the Problem 4-3
Limit the Scope 4-4
Setting the Priority 4-5
Top Wait Events 4-6
Oracle Internal & Oracle Academy Use Only
v
Setting the Priority: Example 4-7
Top SQL Reports 4-8
Common Tuning Problems 4-9
Tuning Life Cycle Phases 4-11
Tuning During the Life Cycle 4-12
Application Design and Development 4-13
Testing: Database Configuration 4-14
Deployment 4-15
Production 4-16
Migration, Upgrade, and Environment Changes 4-17
ADDM Tuning Session 4-18
Performance Versus Business Requirements 4-19
Performance Tuning Resources 4-20
Filing a Performance Service Request 4-21
RDA Report 4-22
Monitoring and Tuning Tool: Overview 4-23
Summary 4-25
Practice 4 Overview: Identifying the Problem 4-26
5 Using Metrics and Alerts
Objectives 5-2
Metrics, Alerts, and Baselines 5-3
Limitation of Base Statistics 5-4
Typical Delta Tools 5-5
Oracle Database 11g Solution: Metrics 5-6
Benefits of Metrics 5-7
Viewing Metric History Information 5-8
Using EM to View Metric Details 5-9
Statistic Histograms 5-10
Histogram Views 5-11
Server-Generated Alerts 5-12
Database Control Usage Model 5-13
Setting Thresholds 5-14
Creating and Testing an Alert 5-15
Metric and Alert Views 5-16
View User-Defined SQL Metrics 5-17
Create User-Defined SQL Metrics 5-18
View User-Defined Host Metrics 5-19
Create User-Defined Host Metrics 5-20
Summary 5-21
Practice Overview 5: Working with Metrics 5-22
Oracle Internal & Oracle Academy Use Only
vi
6 Baselines
Objectives 6-2
Comparative Performance Analysis with AWR Baselines 6-3
Automatic Workload Repository Baselines 6-4
Moving Window Baseline 6-5
Baselines in Performance Page Settings 6-6
Baseline Templates 6-7
AWR Baselines 6-8
Creating AWR Baselines 6-9
Single AWR Baseline 6-10
Creating a Repeating Baseline Template 6-11
Managing Baselines with PL/SQL 6-12
Generating a Baseline Template for a Single Time Period 6-13
Creating a Repeating Baseline Template 6-14
Baseline Views 6-15
Performance Monitoring and Baselines 6-17
Defining Alert Thresholds Using a Static Baseline 6-19
Using EM to Quickly Configure Adaptive Thresholds 6-20
Changing Adaptive Threshold Settings 6-22
Summary 6-23
Practice 6: Overview Using AWR Baselines 6-24
7 Using AWR-Based Tools
Objectives 7-2
Automatic Maintenance Tasks 7-3
Maintenance Windows 7-4
Default Maintenance Plan 7-5
Automated Maintenance Task Priorities 7-6
Tuning Automatic Maintenance Tasks 7-7
ADDM Performance Monitoring 7-8
ADDM and Database Time 7-9
DBTime-Graph and ADDM Methodology 7-10
Top Performance Issues Detected 7-12
Database Control and ADDM Findings 7-13
ADDM Analysis Results 7-14
ADDM Recommendations 7-15
Database Control and ADDM Task 7-16
Changing ADDM Attributes 7-17
Retrieving ADDM Reports by Using SQL 7-18
Active Session History: Overview 7-19
Active Session History: Mechanics 7-20
Oracle Internal & Oracle Academy Use Only
vii
ASH Sampling: Example 7-21
Accessing ASH Data 7-22
Dump ASH to File 7-23
Analyzing the ASH Data 7-24
Generating ASH Reports 7-25
ASH Report Script 7-26
ASH Report: General Section 7-27
ASH Report Structure 7-28
ASH Report: Activity Over Time 7-29
Summary 7-30
Practice 7 Overview: Using AWR-Based Tools 7-31
8 Monitoring an Application
Objectives 8-2
What Is a Service? 8-3
Service Attributes 8-4
Service Types 8-5
Creating Services 8-6
Managing Services in a Single-Instance Environment 8-7
Everything Switches to Services 8-8
Using Services with Client Applications 8-9
Using Services with the Resource Manager 8-10
Services and Resource Manager with EM 8-11
Services and the Resource Manager: Example 8-12
Using Services with the Scheduler 8-13
Services and the Scheduler with EM 8-14
Services and the Scheduler: Example 8-16
Using Services with Parallel Operations 8-17
Using Services with Metric Thresholds 8-18
Changing Service Thresholds by Using EM 8-19
Services and Metric Thresholds: Example 8-20
Service Aggregation and Tracing 8-21
Top Services Performance Page 8-22
Service Aggregation Configuration 8-23
Service Aggregation: Example 8-24
Client Identifier Aggregation and Tracing 8-25
trcsess Utility 8-26
Service Performance Views 8-27
Summary 8-29
Practice 8 Overview: Using Services 8-30
Oracle Internal & Oracle Academy Use Only
viii
9 Identifying Problem SQL Statements
Objectives 9-2
SQL Statement Processing Phases 9-3
Parse Phase 9-4
SQL Storage 9-5
Cursor Usage and Parsing 9-6
SQL Statement Processing Phases: Bind 9-8
SQL Statement Processing Phases: Execute and Fetch 9-9
Processing a DML Statement 9-10
COMMIT Processing 9-12
Role of the Oracle Optimizer 9-13
Identifying Bad SQL 9-15
TOP SQL Reports 9-16
What Is an Execution Plan? 9-17
Methods for Viewing Execution Plans 9-18
Uses of Execution Plans 9-19
DBMS_XPLAN Package: Overview 9-20
EXPLAIN PLAN Command 9-22
EXPLAIN PLAN Command: Example 9-23
EXPLAIN PLAN Command: Output 9-24
Reading an Execution Plan 9-25
Using the V$SQL_PLAN View 9-26
V$SQL_PLAN Columns 9-27
Querying V$SQL_PLAN 9-28
V$SQL_PLAN_STATISTICS View 9-29
Querying the AWR 9-30
SQL*Plus AUTOTRACE 9-32
Using SQL*Plus AUTOTRACE 9-33
SQL*Plus AUTOTRACE: Statistics 9-34
SQL Trace Facility 9-35
How to Use the SQL Trace Facility 9-37
Initialization Parameters 9-38
Enabling SQL Trace 9-40
Disabling SQL Trace 9-41
Formatting Your Trace Files 9-42
TKPROF Command Options 9-43
Output of the TKPROF Command 9-45
TKPROF Output with No Index: Example 9-50
TKPROF Output with Index: Example 9-51
Generate an Optimizer Trace 9-52
Oracle Internal & Oracle Academy Use Only
ix
Summary 9-53
Practice Overview 9: Using Execution Plan Utilities 9-54
10 Influencing the Optimizer
Objectives 10-2
Functions of the Query Optimizer 10-3
Selectivity 10-5
Cardinality and Cost 10-6
Changing Optimizer Behavior 10-7
Using Hints 10-8
Optimizer Statistics 10-9
Extended Statistics 10-10
Controlling the Behavior of the Optimizer with Parameters 10-11
Enabling Query Optimizer Features 10-13
Influencing the Optimizer Approach 10-14
Optimizing SQL Statements 10-15
Access Paths 10-16
Choosing an Access Path 10-17
Full Table Scans 10-18
Row ID Scans 10-20
Index Operations 10-21
B*Tree Index Operations 10-22
Bitmap Indexes 10-23
Bitmap Index Access 10-24
Combining Bitmaps 10-25
Bitmap Operations 10-26
Join Operations 10-27
Join Methods 10-28
Nested Loop Joins 10-29
Hash Joins 10-31
Sort-Merge Joins 10-32
Join Performance 10-34
How the Query Optimizer Chooses Execution Plans for Joins 10-35
Sort Operations 10-37
Tuning Sort Performance 10-38
Reducing the Cost 10-39
Index Maintenance 10-40
Dropping Indexes 10-42
Creating Indexes 10-43
SQL Access Advisor 10-44
Table Maintenance for Performance 10-45
Oracle Internal & Oracle Academy Use Only
x
Table Reorganization Methods 10-46
Summary 10-47
Practice 10 Overview: Influencing the Optimizer 10-48
11 Using SQL Performance Analyzer
Objectives 11-2
Real Application Testing: Overview 11-3
Real Application Testing: Use Cases 11-4
SQL Performance Analyzer: Process 11-5
Capturing the SQL Workload 11-7
Creating a SQL Performance Analyzer Task 11-8
SQL Performance Analyzer: Tasks 11-9
Optimizer Upgrade Simulation 11-10
SQL Performance Analyzer Task Page 11-11
Comparison Report 11-12
Comparison Report SQL Detail 11-13
Tuning Regressing Statements 11-14
Preventing Regressions 11-16
Parameter Change Analysis 11-17
Guided Workflow Analysis 11-18
SQL Performance Analyzer: PL/SQL Example 11-19
SQL Performance Analyzer: Data Dictionary Views 11-21
Summary 11-22
Practice 11: Overview 11-23
12 SQL Performance Management
Objectives 12-2
Maintaining SQL Performance 12-3
Maintaining Optimizer Statistics 12-4
Automated Maintenance Tasks 12-5
Statistic Gathering Options 12-6
Setting Statistic Preferences 12-7
Restore Statistics 12-9
Deferred Statistics Publishing: Overview 12-10
Deferred Statistics Publishing: Example 12-12
Automatic SQL Tuning: Overview 12-13
SQL Statement Profiling 12-14
Plan Tuning Flow and SQL Profile Creation 12-15
SQL Tuning Loop 12-16
Using SQL Profiles 12-17
SQL Tuning Advisor: Overview 12-18
Oracle Internal & Oracle Academy Use Only
xi
Using the SQL Tuning Advisor 12-19
SQL Tuning Advisor Options 12-20
SQL Tuning Advisor Recommendations 12-21
Using the SQL Tuning Advisor: Example 12-22
Using the SQL Access Advisor 12-23
View Recommendations 12-25
View Recommendation Details 12-26
SQL Plan Management: Overview 12-27
SQL Plan Baseline: Architecture 12-28
Loading SQL Plan Baselines 12-30
Evolving SQL Plan Baselines 12-31
Important Baseline SQL Plan Attributes 12-32
SQL Plan Selection 12-34
Possible SQL Plan Manageability Scenarios 12-36
SQL Performance Analyzer and SQL Plan Baseline Scenario 12-37
Loading a SQL Plan Baseline Automatically 12-38
Purging SQL Management Base Policy 12-39
Enterprise Manager and SQL Plan Baselines 12-40
Summary 12-41
Practice 12: Overview Using SQL Plan Management 12-42
13 Using Database Replay
Objectives 13-2
Using Database Replay 13-3
The Big Picture 13-4
System Architecture: Capture 13-5
System Architecture: Processing the Workload 13-7
System Architecture: Replay 13-8
Capture Considerations 13-9
Replay Considerations: Preparation 13-10
Replay Considerations 13-11
Replay Options 13-12
Replay Analysis 13-13
Database Replay Workflow in Enterprise Manager 13-15
Capturing Workload with Enterprise Manager 13-16
Capture Wizard: Plan Environment 13-17
Capture Wizard: Options 13-18
Capture Wizard: Parameters 13-19
Viewing Capture Progress 13-20
Viewing Capture Report 13-21
Export Capture AWR Data 13-22
Oracle Internal & Oracle Academy Use Only
xii
Viewing Workload Capture History 13-23
Processing Captured Workload 13-24
Using the Preprocess Captured Workload Wizard 13-25
Using the Replay Workload Wizard 13-26
Replay Workload: Prerequisites 13-27
Replay Workload: Choose Initial Options 13-28
Replay Workload: Customize Options 13-29
Replay Workload: Prepare Replay Clients 13-30
Replay Workload: Client Connections 13-31
Replay Workload: Replay Started 13-32
Viewing Workload Replay Progress 13-33
Viewing Workload Replay Statistics 13-34
Packages and Procedures 13-36
Data Dictionary Views: Database Replay 13-37
Database Replay: PL/SQL Example 13-38
Calibrating Replay Clients 13-40
Summary 13-41
Practice 13: Overview 13-42
14 Tuning the Shared Pool
Objectives 14-2
Shared Pool Architecture 14-3
Shared Pool Operation 14-4
The Library Cache 14-5
Latch and Mutex 14-7
Latch and Mutex: Views and Statistics 14-9
Diagnostic Tools for Tuning the Shared Pool 14-11
AWR/Statspack Indicators 14-13
Load Profile 14-14
Instance Efficiencies 14-15
Top Waits 14-16
Time Model 14-17
Library Cache Activity 14-19
Avoid Hard Parses 14-20
Are Cursors Being Shared? 14-21
Sharing Cursors 14-23
Adaptive Cursor Sharing: Example 14-25
Adaptive Cursor Sharing Views 14-27
Interacting with Adaptive Cursor Sharing 14-28
Avoiding Soft Parses 14-29
Sizing the Shared Pool 14-30
Oracle Internal & Oracle Academy Use Only
xiii
Shared Pool Advisory 14-31
Shared Pool Advisor 14-33
Avoiding Fragmentation 14-34
Large Memory Requirements 14-35
Tuning the Shared Pool Reserved Space 14-37
Keeping Large Objects 14-39
Data Dictionary Cache 14-41
Dictionary Cache Misses 14-42
SQL Query Result Cache: Overview 14-43
Managing the SQL Query Result Cache 14-44
Using the RESULT_CACHE Hint 14-46
Using the DBMS_RESULT_CACHE Package 14-47
Viewing SQL Result Cache Dictionary Information 14-48
SQL Query Result Cache: Considerations 14-49
UGA and Oracle Shared Server 14-50
Large Pool 14-51
Tuning the Large Pool 14-52
Summary 14-53
Practice Overview 14: Tuning the Shared Pool 14-54
15 Tuning the Buffer Cache
Objectives 15-2
Oracle Database Architecture 15-3
Buffer Cache: Highlights 15-4
Database Buffers 15-5
Buffer Hash Table for Lookups 15-6
Working Sets 15-7
Tuning Goals and Techniques 15-9
Symptoms 15-11
Cache Buffer Chains Latch Contention 15-12
Finding Hot Segments 15-13
Buffer Busy Waits 15-14
Calculating the Buffer Cache Hit Ratio 15-15
Buffer Cache Hit Ratio Is Not Everything 15-16
Interpreting Buffer Cache Hit Ratio 15-17
Read Waits 15-19
Free Buffer Waits 15-21
Solutions 15-22
Sizing the Buffer Cache 15-23
Buffer Cache Size Parameters 15-24
Dynamic Buffer Cache Advisory Parameter 15-25
Oracle Internal & Oracle Academy Use Only
xiv
Buffer Cache Advisory View 15-26
Using the V$DB_CACHE_ADVICE View 15-27
Using the Buffer Cache Advisory with EM 15-28
Caching Tables 15-29
Multiple Buffer Pools 15-30
Enabling Multiple Buffer Pools 15-32
Calculating the Hit Ratio for Multiple Pools 15-33
Multiple Block Sizes 15-35
Multiple Database Writers 15-36
Multiple I/O Slaves 15-37
Use Multiple Writers or I/O Slaves 15-38
Private Pool for I/O Intensive Operations 15-39
Automatically Tuned Multiblock Reads 15-40
Flushing the Buffer Cache (for Testing Only) 15-41
Summary 15-42
Practice 15: Overview Tuning the Buffer Cache 15-43
16 Tuning PGA and Temporary Space
Objectives 16-2
SQL Memory Usage 16-3
Performance Impact 16-4
Automatic PGA Memory 16-5
SQL Memory Manager 16-6
Configuring Automatic PGA Memory 16-8
Setting PGA_AGGREGATE_TARGET Initially 16-9
Monitoring SQL Memory Usage 16-10
Monitoring SQL Memory Usage: Examples 16-12
Tuning SQL Memory Usage 16-13
PGA Target Advice Statistics 16-14
PGA Target Advice Histograms 16-15
Automatic PGA and Enterprise Manager 16-16
Automatic PGA and AWR Reports 16-17
Temporary Tablespace Management: Overview 16-18
Temporary Tablespace: Best Practice 16-19
Configuring Temporary Tablespace 16-20
Temporary Tablespace Group: Overview 16-22
Temporary Tablespace Group: Benefits 16-23
Creating Temporary Tablespace Groups 16-24
Maintaining Temporary Tablespace Groups 16-25
View Tablespace Groups 16-26
Monitoring Temporary Tablespace 16-27
Oracle Internal & Oracle Academy Use Only
xv
Temporary Tablespace Shrink 16-28
Tablespace Option for Creating Temporary Table 16-29
Summary 16-30
Practice Overview 16: Tuning PGA Memory 16-31
17 Automatic Memory Management
Objectives 17-2
Oracle Database Architecture 17-3
Dynamic SGA 17-4
Granule 17-5
Memory Advisories 17-6
Manually Adding Granules to Components 17-7
Increasing the Size of an SGA Component 17-8
Automatic Shared Memory Management: Overview 17-9
SGA Sizing Parameters: Overview 17-10
Dynamic SGA Transfer Modes 17-11
Memory Broker Architecture 17-12
Manually Resizing Dynamic SGA Parameters 17-13
Behavior of Auto-Tuned SGA Parameters 17-14
Behavior of Manually Tuned SGA Parameters 17-15
Using the V$PARAMETER View 17-16
Resizing SGA_TARGET 17-17
Disabling Automatic Shared Memory Management 17-18
Configuring ASMM 17-19
SGA Advisor 17-20
Monitoring ASMM 17-21
Automatic Memory Management: Overview 17-22
Oracle Database Memory Parameters 17-24
Automatic Memory Parameter Dependency 17-25
Enabling Automatic Memory Management 17-26
Monitoring Automatic Memory Management 17-27
DBCA and Automatic Memory Management 17-29
Summary 17-30
Practice 17: Overview Using Automatic Memory Tuning 17-31
Oracle Internal & Oracle Academy Use Only
xvi
18 Tuning Segment Space Usage
Objectives 18-2
Space Management 18-3
Extent Management 18-4
Locally Managed Extents 18-5
Large Extents: Considerations 18-6
How Table Data Is Stored 18-8
Anatomy of a Database Block 18-9
Minimize Block Visits 18-10
The DB_BLOCK_SIZE Parameter 18-11
Small Block Size: Considerations 18-12
Large Block Size: Considerations 18-13
Block Allocation 18-14
Free Lists 18-15
Block Space Management 18-16
Block Space Management with Free Lists 18-17
Automatic Segment Space Management 18-19
Automatic Segment Space Management at Work 18-20
Block Space Management with ASSM 18-22
Creating an Automatic Segment Space Management Segment 18-23
Migration and Chaining 18-24
Guidelines for PCTFREE and PCTUSED 18-26
Detecting Migration and Chaining 18-27
Selecting Migrated Rows 18-28
Eliminating Migrated Rows 18-29
Shrinking Segments: Overview 18-31
Shrinking Segments: Considerations 18-32
Shrinking Segments by Using SQL 18-33
Segment Shrink: Basic Execution 18-34
Segment Shrink: Execution Considerations 18-35
Using EM to Shrink Segments 18-36
Table Compression: Overview 18-37
Table Compression Concepts 18-38
Using Table Compression 18-39
Summary 18-40
19 Tuning I/O
Objectives 19-2
I/O Architecture 19-3
File System Characteristics 19-4
I/O Modes 19-5
Oracle Internal & Oracle Academy Use Only
xvii
Direct I/O 19-6
Bandwidth Versus Size 19-7
Important I/O Metrics for Oracle Databases 19-8
I/O Calibration and Enterprise Manager 19-10
I/O Calibration and the PL/SQL Interface 19-11
I/O Statistics: Overview 19-13
I/O Statistics and Enterprise Manager 19-14
Stripe and Mirror Everything 19-16
Using RAID 19-17
RAID Cost Versus Benefits 19-18
Should I Use RAID 1 or RAID 5? 19-20
Diagnostics 19-21
Database I/O Tuning 19-22
What Is Automatic Storage Management? 19-23
Tuning ASM 19-24
How Many Disk Groups per Database 19-25
Which RAID Configuration for Best Availability? 19-26
ASM Mirroring Guidelines 19-27
ASM Striping Granularity 19-28
What Type of Striping Works Best? 19-29
ASM Striping Only 19-30
Hardware RAID Striped LUNs 19-31
ASM Guidelines 19-32
ASM Instance Initialization Parameters 19-33
Dynamic Performance Views 19-34
Monitoring Long-Running Operations by Using V$ASM_OPERATION 19-36
ASM Instance Performance Diagnostics 19-37
ASM Performance Page 19-38
Database Instance Parameter Changes 19-39
ASM Scalability 19-40
Summary 19-41
20 Performance Tuning Summary
Objectives 20-2
Necessary Initialization Parameters with Little Performance Impact 20-3
Important Initialization Parameters with Performance Impact 20-4
Sizing Memory Initially 20-6
Database High Availability: Best Practices 20-7
Undo Tablespace: Best Practices 20-8
Temporary Tablespace: Best Practices 20-9
General Tablespace: Best Practices 20-11
Internal Fragmentation Considerations 20-12
Oracle Internal & Oracle Academy Use Only
xviii
Block Size: Advantages and Disadvantages 20-13
Automatic Checkpoint Tuning 20-14
Sizing the Redo Log Buffer 20-15
Sizing Redo Log Files 20-16
Increasing the Performance of Archiving 20-17
Automatic Statistics Gathering 20-19
Automatic Statistics Collection: Considerations 20-20
Commonly Observed Wait Events 20-21
Additional Statistics 20-22
Top 10 Mistakes Found in Customer Systems 20-23
Summary 20-25
Appendix A: Practices and Solutions
Appendix B: Using Statspack
Index

Shut immediate taking too long

hello,
SQL> shut immediate;
taking too long and no update, what should i do?

nomee wrote:
hello,
SQL> shut immediate;
taking too long and no update, what should i do?The same request I made to everybody, "Just pretend we don't know any thing about your environment. picture it with as much detail as possible".
Figure out ... you are the mechanics and suddenly I arrive and I say ... my car doesn't seem to work fine, what do you think it is?
In this case it is very important to know the version, it normally has to do with checkpoint tuning, number of transactions, number of datafiles. So I suggest you to detail what are you talking about please.
~ Madrid
http://hrivera99.blogspot.com

'fast_start_mttr_target=300'

HI all,
i've been reading about this parmeter 'fast_start_mttr_target=300'..but i coundnt get proper idea..
it just means that if oracle is taking long time to recover then it should not go beyond this time to restart or something else ralated to it?
in the mean time i got the idea about incremental checkpoint and cache recovery(rolling forward stage)..
but has got obscure knowledge of 'fast_start_mttr_target'
how exactly it helps to reduce the time in recovery and what exactly it does?
it will be a great help for me!!
Thanx in Advance!!!

Hi,
I suggest you to read the two articles below, maybe help you:
Automated Checkpoint Tuning (MTTR)
http://www.akadia.com/
Recovery Enhancements In Oracle9i
http://www.oracle-base.com/articles/9i/RecoveryEnhancements9i.php
Cheers

FAST_START_MTTR_TARGET parameter advice

Hello
I need some advice in setting the FAST_START_MTTR_TARGET initialization parameter. There is a lot of valuable documentation and blog posts out there but I am unable to find concrete guidance on this.
In reading the Checkpoint Tuning and Troubleshooting Guide (147468.1), there is mention of 4 total parameters (including FAST_START_MTTR_TARGET) that need to be visited in order to set this:
- FAST_START_MTTR_TARGET
- LOG_CHECKPOINT_INTERVAL
- LOG_CHECKPOINT_TIMEOUT
- LOG_CHECKPOINTS_TO_ALERT
My current db server environment settings are as follows:
W2K8-R2-Std, 11g-11.2.0.1.0-Std
OS-block-size = 4096 bytes
The current initialization parameter settings are:
FAST_START_MTTR_TARGET = 0
LOG_CHECKPOINT_INTERVAL = 0
LOG_CHECKPOINT_TIMEOUT = 1800
LOG_CHECKPOINTS_TO_ALERT = FALSE
The current redo log files are set at 51,200KB.
The condition warranting this is these entries in the alert log:
Thread 1 cannot allocate new log, sequence 117424
Private strand flush not complete
Current log# 1 seq# 117423 mem# 0: K:\ORACLE_SID\REDOG1M1.LOG
Current log# 1 seq# 117423 mem# 1: L:\ORACLE_SID\REDOG1M2.LOG
Thread 1 advanced to log sequence 117424 (LGWR switch)
Current log# 3 seq# 117424 mem# 0: D:\APP\ORADATA\ORACLE_SID\REDOG3M1.LOG
Current log# 3 seq# 117424 mem# 1: L:\ORACLE_SID\REDOG3M2.LOG
Kindly advise. Thank you in advance.

Look in your alert log to see how long it is between redo switches during times of heavy usage. Multiply the size of the redo by how much it would take to switch every 30 minutes. For example, if you switch every 5 minutes, multiply by 6. Then make them much larger and rely on the 1800 second timeout (or better, do the figuring during maximal loading or batch update times). Let it run a few days then check the advisor as in http://docs.oracle.com/cd/E25178_01/server.1111/e16638/build_db.htm#autoId3
Here's the proper way to figure FSMT http://docs.oracle.com/cd/E25178_01/server.1111/e16638/instance_tune.htm#PFGRF13015
Don't bother changing dbw settings yet. Wait until you see some evidence you need to do that.

Query about Log_Checkpoint_interval Parameter

What's the utility for Log_Checkpoint_interval ? Does it have any impact on performance of DB?

What kind of problems are you experiencing ?
Have a look at this note:
Checkpoint Tuning and Troubleshooting Guide [ID 147468.1]
LOG_CHECKPOINT_INTERVAL influences when a checkpoint occurs, which means
careful attention should be given to the setting of this parameter, keeping it
updated as the size of the redo log files is changed. The checkpoint
frequency is one of the factors which impacts the time required for the
database to recover from an unexpected failure. Longer intervals between
checkpoints mean that if the system crashes, more time will be needed for the
database to recover. Shorter checkpoint intervals mean that the database will
recover more quickly, at the expense of increased resource utilization during
the checkpoint operation.
...

Checkpoint tuning

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