SGA advisor

Hi,
on 10g R2, can we find what is advised on Dbconsole (DBCONTROLE) on SGA (Advisor Central/Memory Advisor/ SGA tab Advice) in a table by a query ?
Actually in Performance Tuning Guide I found the following for cache size :
COLUMN size_for_estimate FORMAT 999,999,999,999 heading 'Cache Size (MB)'
COLUMN buffers_for_estimate FORMAT 999,999,999 heading 'Buffers'
COLUMN estd_physical_read_factor FORMAT 999.90 heading 'Estd Phys|Read Factor'
COLUMN estd_physical_reads FORMAT 999,999,999 heading 'Estd Phys| Reads'
SELECT size_for_estimate, buffers_for_estimate, estd_physical_read_factor, estd_physical_reads
FROM V$DB_CACHE_ADVICE
WHERE name = 'DEFAULT'
AND block_size = (SELECT value FROM V$PARAMETER WHERE name = 'db_block_size')
AND advice_status = 'ON';Thank you.

Hello,
can we find what is advised on Dbconsole (DBCONTROLE) on SGA (Advisor Central/Memory Advisor/ SGA tab Advice) in a table by a query ?You may execute the Query below so as to get the list of all the Views related to the various Advisors:
SQL> select table_name from dict where table_name like '%ADVICE%';
TABLE_NAME
DBA_HIST_DB_CACHE_ADVICE
DBA_HIST_JAVA_POOL_ADVICE
DBA_HIST_MEMORY_TARGET_ADVICE
DBA_HIST_MTTR_TARGET_ADVICE
DBA_HIST_PGA_TARGET_ADVICE
DBA_HIST_SGA_TARGET_ADVICE
DBA_HIST_SHARED_POOL_ADVICE
DBA_HIST_STREAMS_POOL_ADVICE
V$MEMORY_TARGET_ADVICE
V$MTTR_TARGET_ADVICE
V$PGA_TARGET_ADVICE
TABLE_NAME
V$PGA_TARGET_ADVICE_HISTOGRAM
V$PX_BUFFER_ADVICE
V$SGA_TARGET_ADVICE
V$SHARED_POOL_ADVICE
V$STREAMS_POOL_ADVICE
GV$JAVA_POOL_ADVICE
GV$SGA_TARGET_ADVICE
GV$SHARED_POOL_ADVICE
V$JAVA_POOL_ADVICE
GV$DB_CACHE_ADVICE
GV$MEMORY_TARGET_ADVICE
TABLE_NAME
GV$MTTR_TARGET_ADVICE
GV$PGA_TARGET_ADVICE_HISTOGRAM
GV$PGA_TARGET_ADVICE
GV$PX_BUFFER_ADVICE
V$DB_CACHE_ADVICE
GV$STREAMS_POOL_ADVICE
28 ligne(s) sÚlectionnÚe(s).Then, you have just to check on the REFERENCE book for the complete description of each of these Views:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/dynviews_part.htm#i403961
Hope this help.
Best regards,
Jean-Valentin

Similar Messages

Oracle sga advisor results

hello all,
When querying this view in regards to the v$sga_shared_pool advisory , i get results but not sure how to interpret the ESTD_LC_TIME_SAVED column ?
It's a time in seconds benchmark to what exactly ?
EST_SIZE FACTOR ESTD_LC_SIZE ESTD_LC_TIME_SAVED HITS
160 0.5 162 215103 43148850
192 0.6 193 215285 43173155
224 0.7 224 215391 43188435
256 0.8 255 215470 43200068
Thanks

ESTD_LC_TIME_SAVED - (From Oracle documentation) Estimated elapsed parse time saved (in seconds), owing to library cache memory objects being found in a shared pool of the specified size. This is the time that would have been spent in reloading the required objects in the shared pool had they been aged out due to insufficient amount of available free memory.
ESTD_LC_TIME_SAVED_FACTOR - indicates how the ESTD_LC_TIME_SAVED relates to the current shared pool.
reference: http://www.alydan.com/weeklytip060.htm
--hope this helps!

Should I use shared pool advisor?

Hi, I am new to the Oracle DB and preparing for the first test of the OCA. If there is a SQL statement that is parsing repeatly, should I use shared pool advisor or SGA advisor?
thanks a lot for help

user592813 wrote:
Hi, I am new to the Oracle DB and preparing for the first test of the OCA. If there is a SQL statement that is parsing repeatly, should I use shared pool advisor or SGA advisor?
thanks a lot for helpYou need to tell us that what do you mean by "parse" here? Is it a soft parse or hard parse? If its a hard parse, and you have made sure that your application has not used literals , you may look at the shared pool for being undersized by its sizing advisory. If you have a bad code in the application throwing unsharable queries, there is no point of increasing the shared pool as at any one point of time,it would become useless. For this, the fix would be tune the queries and not to resize the shared pool.
If on the other hand, you have soft parsing happening, you can further try to optimize it by making it "no parsing" using the parameter session_cached_cursors . But for this as well, there is no need to increase the size of the shared pool.
HTH
Aman....

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
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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
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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
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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
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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
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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
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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
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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
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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

Performance Testing While Caching?

Fellas,
I am doing performance optimization tasks on oracle DB 10G R2 running on Red Hat Linux.
The problem is that whenever I run the query twice or more, oracle caches it, and I can no Longer see the delays in execution times.
I tried to clear the cache (this is Dev environment) but query execution times behaved as if the execution plans are still cached.
Any insight, please?

Charlov wrote:
Fellas,
I am doing performance optimization tasks on oracle DB 10G R2 running on Red Hat Linux.
The problem is that whenever I run the query twice or more, oracle caches it, and I can no Longer see the delays in execution times.
I tried to clear the cache (this is Dev environment) but query execution times behaved as if the execution plans are still cached.
Any insight, please?If you are doing performance optimization, why do you not want caching? Don't you want to optimize the access to data, whether it is cached or not? User perceived execution time is a reason to investigate performance, but it is difficult to map a development execution time to real world performance. That's why people say things like minimize consistent gets or concentrate on logical I/O.
So if you are investigating how to maximize getting data from a disk to the SGA, because you have infrequent unique queries, do that. Multiblock reads or not bothering with the SGA may be your friend. If you have data that is getting flushed out of the SGA even though it is being accessed moderately frequently, check the SGA advisor and consider the KEEP pool. If you don't know where the caching is occurring - it could be the SGA, OS user buffers, controller cache, SAN cache - you need to either figure it out or ignore it.
Perhaps if you told us how exactly you are "doing performance optimization tasks" we could give better advice.
Oracle purposefully reuses execution plans - this avoids much worse performance problems from hard parsing creating new ones. There are situations where this is bad (google the bind peeking problem). If you want a new execution plan, give a different query. Comments are useful for that, as well as being something to look for in the sql area.

Orace performance getting very very slow

Hi Experts ,
Past few months we are facing some oracle performance issue in our database .
My database details given below
Please give your valuable advice to increase the database performance
Database version = Oracle 10g ,10.2.0.4.0 ,R12
Database size = 450GB
platform =Linux RHEL 4.4 32 bit
SGA size = 2Gb (16GB ram) (when i increase the sga max size 2gb to 4gb getting error out of memory )
Regards
Vicky

Hi;
Past few months we are facing some oracle performance issue in our database . Define what is slow, its very deeply subject about performance. CM slow or response slow etc.
Did you check AWR report?ASH also ADDM?
Database version = Oracle 10g ,10.2.0.4.0 ,R12
Database size = 450GB
platform =Linux RHEL 4.4 32 bit
SGA size = 2Gb (16GB ram) (when i increase the sga max size 2gb to 4gb getting error out of memory )What is EBS version?
1. You need to upgrade your db
2. Did you check SGA advisor? What AWR report says
I suggest review:
Re: applications hangs slow
Regard
Helios

Object name, segment advisor and db sequential read

oracle 10.2.0.4:
I am looking at our ADDM and AWR report. It's complaining about db file sequential read waits and also "Segment Advisor" on LOB SYS_LOB.... I have couple of questions:
1. When select is fired (from JDBC/hibernate) with the column that is of type BLOB does the blob gets extracted at that point or just the reference is returned to the BLOB. And only when that column is accessed then the blob is fetched. Or does it get fetched right away in the "Select statemement"?
2. I see Sedgment Advisor on object name LOB SYS_LOB000000012511C000006$$. How do I know which column/table it's referring to.
3. db file sequential read waits means that something is wrong with disk layout?
4. Even though our IO is not that high ADDM keeps complaining about increasing SGA to 64G. Currently as it is 32G and it's huge. Could it be because of above reasons that it thinks that it needs larger SGA?

We are expecting a very high load in coming days. So I was looking at the system to check if somethings needs to be improved beforehand. I see things like 'User I/O waiting on Hot Objects", "db file sequential read waits". I read about it but I am not sure how to really see if it's going to be a problem or if it's a problem. We have indexes but one of the queries selects blob and is not always used so I was wondering if db file sequential read is being caused by that. I am not sure why we would have waiting on Hot objects because currently our system in not very busy. Hot object is a LOB and it's partitioned. It says database object with id XXXX, 0 full object scansm 25336 physical and direct reds. I know the table by looking up in DBA_LOBS.

Oracle SGA benefits of using indexes

Goo day people,
We have been having performance issues and then the SGA was not sized coprrectely.
The size of the SGA was 720mb so we then pushed it to 4 gig which I blv is enough.
We then did a run of the tuning advisory on the top sql queries that were top one,
the advisor then pointed on that we need to use indexes on those queries .
We then advised the developers that they need to use indexes as it will improve
performance .. This morning the ADDM pointed out that we need to up the sga
to 5 Gig and I dont see this a solution to the problem.
I need to find a note on what benefits does using indexes have on the SGA and the overall perfomance
so that I can show the business that increasing the SGA wont solve the problem.
See screen shot below
erformance Finding Details:
     Database Time (minutes)          33.8
     Period Start Time          10-Aug-2010 10:00:11 o'clock SAST
     Period Duration (minutes)          60.2
     Task Owner          SYS
     Task Name          ADDM:1511773678_1_28498
     Average Active Sessions          0.6
     Finding          The SGA was inadequately sized, causing additional I/O or hard parses.
     Impact (minutes)          14.4
     Impact (%)          [64] [86] 42.8
Recommendations
Show All Details | Hide All Details
Details     Category     Benefit (%) [Sorted in descending order]
[Select to hide information] Hide
     DB Configuration     [64] [86] 42.8
Action     Increase the size of the SGA by setting the parameter "sga_target" to 5120 M.
Thanks
Sibusiso
Edited by: 787473 on 10-Aug-2010 02:35

We have been having performance issues and then the SGA was not sized coprrectely.
The size of the SGA was 720mb so we then pushed it to 4 gig which I blv is enough.
We then did a run of the tuning advisory on the top sql queries that were top one,
the advisor then pointed on that we need to use indexes on those queries .
We then advised the developers that they need to use indexes as it will improve
performance .. Yes. As those queries must be missing indexes that would prove to be beneficial. So need to take it query by query and created the required indexes.
This morning the ADDM pointed out that we need to up the sga
to 5 Gig and I dont see this a solution to the problem.
I need to find a note on what benefits does using indexes have on the SGA and the overall perfomance
so that I can show the business that increasing the SGA wont solve the problem.
See screen shot below
erformance Finding Details:
     Database Time (minutes)          33.8
     Period Start Time          10-Aug-2010 10:00:11 o'clock SAST
     Period Duration (minutes)          60.2
     Task Owner          SYS
     Task Name          ADDM:1511773678_1_28498
     Average Active Sessions          0.6
     Finding          The SGA was inadequately sized, causing additional I/O or hard parses.
     Impact (minutes)          14.4
     Impact (%)          [64] [86] 42.8
Recommendations
Show All Details | Hide All Details
Details     Category     Benefit (%) [Sorted in descending order]
[Select to hide information] Hide
     DB Configuration     [64] [86] 42.8
Action     Increase the size of the SGA by setting the parameter "sga_target" to 5120 M.One of the biggest impact of indexes (if they fit in the scenario) is in reducing the IO (by avoiding full table scans). Reduced IO means faster system. Absence of indexes would mean that you read lots of data into the memory [buffer cache] and data would flush out quickly too (to make space for the new data), resulting in more IO. So having indexes in place means you only read as much amount of data as required and frequently accessed data stays in the memory.
Kinda incomplete answer...Lets wait for other experts' comments :)
Edited by: amardeep.sidhu on Aug 10, 2010 3:23 PM

The SGA was inadequately sized, causing additional I/O or hard parses.

Dear all,
We are using 10g RAC On Solaris 5.10
Very freuently,we are getting the below message in DB Console
The SGA was inadequately sized, causing additional I/O or hard parses.
Additional Information
The value of parameter "sga_target" was "15360 M" during the analysis period.
Under recommendations,
I found that
Increase the size of the SGA by setting the parameter "sga_target" to 30720 M.
Findings Path
Findings Impact (%) Additional Information
The SGA was inadequately sized, causing additional I/O or hard parses. 27 Additional Information
Wait class "User I/O" was consuming significant database time. 13.2
Hard parsing of SQL statements was consuming significant database time. 4.9
Contention for latches related to the shared pool was consuming significant database time. 0.6
Wait class "Concurrency" was consuming significant database time
Can I rely on this info alone and increase SGA.. Is there any other way I confirm this ?.
Dear Seniors,
Please ignore this Thread if you find this question silly..
Please advise
Kai

Hi Kai,
Can I rely on this info alone and increase SGA.. Is there any other way I confirm this ?.Yes. Oracle has specific "cache" advisors to say if your data buffers of shared pool regions are too small.
I have my notes here:
http://www.dba-oracle.com/art_builder_buffers.htm
The besy way to see them is to run a STATSPACK or AWR report . . .
if you find this question silly..It''s not silly at all, it's a VERY common question!
http://www.dba-oracle.com/t_estimating_sga_size.htm
If you are running Oracle on a dedicated server, it's wasteful NOT to allocate all of the RAM to Oracle, less 20% for the OS . . .
Lastly, remember that Oracle has an insatiable appetite for RAM, but there is a point of diminishing marginal return . . .
Hope this helps . . .
Donald K. Burleson
Oracle Press author
Author of "Oracle Tuning: The Definitive Reference"
http://www.rampant-books.com/book_2005_1_awr_proactive_tuning.htm

SGA & PGA target

Hi all,
My questions is regarding how to set up SGA & PGA target values giving DB server is MS 2003 Enterprise 64 edition sever with 63 GB of RAM. Our DB’s version is 10.2.0.3 and RACed with 2 instances.
Currently our setting for SGA is 23 GB and PGA is 4 GB. I ran the memory advisor it display different optimal values for those two instances (35 GB and 23 GB for SGA, 5 GB and 4 GB for PGA). Guess our db is not well balance loaded.
I would like to know if there is any rule(s) that SGA can’t be more than certain percentage of total RAM for the server.
Thanks a lot in advance.
Have a great weekend!!
Shirley

Hi
Here is my approach:
1) consider free physical memory (meassure must be taken with Oracle down)
2) substract a 10% of that amount as a margin
3) if the box is exclusive for Oracle, the remaining amount may be your SGA+PGA limit
4) if not is exclusive, then substract memory required for other services, then you'll get the SGA+PGA limit.
5) Substract your PGA size, giving the SGA figure
For instance
59 Gb - 6 Gb = 53 Gb - 4 Gb = 49 Gb
(63 Gb -4 Gb [estimated OS footprint + IO cache]) = 59 Gb free physical memory
Setting PGA+SGA beyond the free physical memory figure, may lead to swaping and degraded system performance.
Regards
http://oracledisect.blogspot.com

SGA PGA screen

In OEM 10.2 there was a nifty screen that showed the SGA used, and how memory was being allocated within each of the components.
I have looked everywhere in em12c for this function, but am missing it for some reason.
Can someone point me in the right direction?

Thank you. I had to:
Database Home --> Performance Menu --> Advisor Central --> Memory Advisors.
Appreciate the help.

SGA Sizing

Dear Experts
is there any formula to size SGA in 32bit and 64bit. with 4GB or 16GB RAM.
regards
saima

user2108660 wrote:
Dear Experts
is there any formula to size SGA in 32bit and 64bit. with 4GB or 16GB RAM.
regards
saimaThere is no such formula and do not need AFAIK.But there is main matter is supporting memory like 32bit systems can be support maximum 4G(possible).But in your case you mean is tuning SGA.So its depend your system activities.You have to use Memory Advisor through Enterprise Manager or dynamic performance views(like v$SGA_TARGET_ADVICE).

SGA & PGA concept

We have a production Oracle 11g DB in which SGA_TARGET is 0 but ASSM is enabled but the documentation on Oracle says that if SGA_TARGET is 0 means that ASSM is disabled. Also, PGA_AGGREGATE_TARGET is 0 but Maximum PGA allocated is around 1 GB.
I hope, my question is clear that concept seems to be confusing where SGA_TARGET is 0 but ASSM is enabled and also PGA_AGGREGATE_TARGET is 0 but maximum PGA allocated is 1 GB.
Please revert with the reply to my query.
Regards

972145 wrote:
Thanks for your reply but there is some confusion. ASMM is automatic shared memory management which seems to be similar to AMM which is automatic memory management. ASMM can be seen from OEM under Database Configuration->Memory Advisors. I guess, there is ASM which is automatic storage management to do with reduntant copies of data to provide fault tolerance.
ASMM - 10g setting for the automatic SGA using the parameter sga_target .
AMM - 11g setting for both SGA and PGA, uses the parameter memory_target
ASM - Automatic Storage Management, nothing to do with SGA or PGA
ASSM - Automatic Segment Space Management, for the tables and nothing to do with the PGA and SGA
Aman....
Edited by: Aman.... on Jan 21, 2013 3:53 PM corrected the typo

SGA in memory

I've made an application in VB that works against an Oracle Spatial db. Running the program takes extremely long time, and I'm trying to speed up the whole application. Therefor I've tested locking the SGA in the memory instead of reading from disk. This didn't work at all, even though I have 100 Mb available physical memory and the SGA only takes 55 Mb (according to the 'Show sga').
I've also tried altering the initialization parameters 'db_block_buffers' and 'log_buffer', without any success.
What am I doing wrong? Any tips or hints?
Thanks, Pelle

Hi Pelle,
I would recommend executing the Oracle
Spatial query from SQL*Plus to see
the spatial performance impact in your
application.
Please see the technical white paper on
technet under products/spatial for
performance enhancement tips.
Some critical tips for Oracle 8.1.6 is
use a fixed index and also to analyze
the spatial index table. These items are
discussed in the performance white paper.
You may also want to try the Spatial Index Advisor which is part of OEM to help tune your spatial indexes. The performance white paper discusses how to use the Spatial Index Advisor effectively.
Hope this helps. Thanks.
Dan

Increase SGA Size

HI,
EBS- 12.0.6
DB- 10.2.0.3
I found this in the ADDM Report ---
FINDING 1: 100% impact (18551 seconds)
The SGA was inadequately sized, causing additional I/O or hard parses.
RECOMMENDATION 1: DB Configuration, 100% benefit (18551 seconds)
ACTION: Increase the size of the SGA by setting the parameter
"sga_target" to 3140 M.
ADDITIONAL INFORMATION:
The value of parameter "sga_target" was "2512 M" during the analysis
period.
SYMPTOMS THAT LED TO THE FINDING:
SYMPTOM: Wait class "User I/O" was consuming significant database time.
(43% impact [7964 seconds])
SYMPTOM: Hard parsing of SQL statements was consuming significant
database time. (3.1% impact [577 seconds])
Workarround :
1. Make the entry in the pfile as sga_max_size=3500M.
2. Shutdown the DB
3. Startup the DB with the pfile
4. SQL>CREATE SPFILE='path of the spfile' FROM PFILE"
5. Shutdown Immediate
6. Startup the DB with the newly created spfile " SQL>STARTUP SPFILE='path of the spfile' "
7 sql> show parameter sga to make sure your changes takes effect
Please correct me if am wrong ..
Thanks

you have to tune the application layer , check top ten query in AWR within perfromance tab , run SQL tuning advisor for each query and see the recommendations , implemnet recommendations , as i have expericence it alls due to huge IO occuring at database (i.e Full Table Scan) due to missing index , if index is not being used then check if any function is used on index coulm (it inhabit skip index usage) then try to avoid function over index column or create function based index. You may need to run explain plan of that query or tkprof tool to identify what optimizer is taking route to fetch data.Check also stats are gathered on tables and index properly.
I have got eliminated function over indexed column by giving alternate to our techno functional consultant.

SGA advisor

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