WELCOME TO

ABOUT ME

KARAN DODWAL (OCM)

Over 8 years of experience with oracle technology

Oracle Certified Master DBA 11G

Oracle Database Architect

Author of OTN Articles

Oracle Certified PLSQL Developer

Oracle Database Instructor http://karandba.blogspot.in/

http://education.oracle.com/education/otn/KDodwal.html

https://www.linkedin.com/pub/karan-dodwal-ocm/2b/b2b/765

Email :- karandodwal@gmail.com

AGENDA

Issues faced in the past without SPM

What is SPM

Architecture of SPM

Why use SPM

Managing SPM

Transporting SPM

Upgrade Strategies

Whats new in 12C

Best Practices

NIGHTMARE OF ANY DBA ?

Execution plan changes badly

SCENARIO 1

Poor performance

Dev Team Complaints

DBA analysis :- Bad Plan

Suggestion :- Hints to fix a plan ???

Dev Team :- Fix the problem without changing

the source code

SCENARIO 2

Poor performance

Dev team complaints

DBA analysis :- Bad Plan

Cause :- Statistics

Dev Team :- Kindly Fix the problem

SCENARIO 3

Poor performance

Dev team complaints

DBA analysis :- Bad Plan

Cause :- SQL Profile

Dev Team :- Kindly Fix the problem

SCENARIO 4

Poor performance of few SQL post upgrade

Lets say 10G to 11G

Dev team complaints and asks has the upgrade

caused the slowness ?

DBA Team :- Speechless

Cause :- Optimizer Version Change

Dev Team :- Lets have a con call

COMMON REASONS OF PLANS CHANGE

New optimizer version

Changes to optimizer statistics

Changes to optimizer parameters

Changes to schema

Changes to system settings

SQL profile creation

SO WHATS WRONG WITH STORED OUTLINES ?

Forcefully use an execution plan

Uses hints

Preferred over SPM when use_stored_outlines

is true

Not a good approach

Should be migrated to SPM

SQL PROFILES ARE NOT PROACTIVE

Recommended by SQL Tuning Advisor

SQL Profiles v/s SPM

SPM V/S SQL PROFILES

SQL Profiles are reactive

SPM is Proactive

SPM reproduces a specific plan

SQL Profile corrects CBO Estimates

SQL Profiles don’t guarantee plan stability

SPM provides plan stability

SQL PLAN MANAGEMENT (SPM)

Introduced in 11G

Preserves the performance

Only accepted plans are used

New plans are saved for future evolution

Enhanced in 12C

Whole idea is to avoid using new plan

SPM BASELINES

Proactive and a Conservative Approach

Guarantee execution plan stability

Only accepted/verified plans are used

Enforce specific plans

New plans are stored in Plan History

Purges history according to retention

SPM ARCHITECTURE

FLOW CHART OF AUTO CAPTURE

CONTROLLING SPM BASELINES

OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES

OPTIMIZER_USE_SQL_PLAN_BASELINES

DBMS_SPM

LOADING PLANS IN BASELINES

From Cursor Cache

From Sql Tuning Set

Migrate from Stored Outlines

Unpack from Staging Table (Using STS)

LOAD PLANS FROM CURSOR CACHE

LOAD PLANS FROM STS

DISPLAY THE BASELINES

Package DBMS_XPLAN has a function called

display_sql_plan_baseline:

select * from table (

dbms_xplan.display_sql_plan_baseline (

sql_handle=>'SYS_SQL_9804ihk4287d3257',

format=>'basic')

)

FIXING A PLAN

dbms_spm.alter_sql_plan_baseline (

sql_handle => ‘SYS_SQL_9804ihk4287d3257’, plan_name => ‘SYS_SQL_PLAN_8421adga5ha456’, attribute_name => 'fixed',

attribute_value => 'YES')

• Fixed plan will be given priority

• More than one plan can be fixed

• In that case optimizer chooses the best from them

• To make a plan“unfix”, use attribute_value => ‘NO'

QUERING STORED OUTLINES

MIGRATE FROM OUTLINES

SQL> variable v clob

SQL> execute :v :=

dbms_spm.migrate_stored_outline

(attribute_name=>'outline_name',

attribute_value=>

'SYS_OUTLINE_14090100280772402',

fixed=>'NO');

PLAN EVOLUTION

QUERYING SPM DATA

CONFIRMING THE USE OF SPM

OEM INTERFACE

From home page click on server tab

Click on Plan Management

Search your SQL

DICTIONARY VIEWS

DBA_SQL_PLAN_BASELINES

Columns :-

accepted, enabled, fixed, last_verified

DBA_SQL_MANAGEMENT_CONFIG

Columns :-

parameter_name, parameter_value

MORE INTERNAL DICTIONARY OBJECTS

Oracle Performs merge for SPM on following

# SQLOBJ$

# SQLOBJ$DATA;

# SQLOBJ$AUXDATA

# SQLLOG$

SQL STATEMENTS LOGGING

PURGING POLICY OF SPM

SPACE USAGE OF SPM

DROPPING SQL PLAN BASELINES

DROP ENTIRE SPM REPOSITORY

IMPORTING AND EXPORTING SQL PLAN

BASELINES

PACK THE STAGE TABLE

PACK A SPECIFIC BASELINE PLAN OF A QUERY

METHODOLOGY

Export the staging table stg1 into a flat file

using the export command or Oracle Data

Pump.

Transfer the flat file to the target system.

Import the staging table stg1 from the flat file

using the import command or Oracle Data

Pump.

UNPACK THE STAGE TABLE

ISSUES

Sql Plan Baseline Not getting created ?

SQL should be be executed twice or more

Does not acknowledge recursive queries

LICENSING QUESTION

What License do I need for SPM ?

LICENSING SPM

SPM is available as part of EE 11g/12C

Tuning pack involves auto plan evolution(12c)

Interaction with Tuning Advisor requires tuning

pack

Tuning pack or RAT pack required to load from

Sql Tuning Set into SPM

So whats new in 12C ?

NEW AUTO EVOLUTION TASK

New task SYS_AUTO_SPM_EVOLVE_TASK

Runs in nightly maintenance window

Poor plans stay for 30 days only if sql is active

Use dbms_Spm.report.auto_evolve_task to

view results of auto job

Auto plan evolution is part of tuning pack

SPM EVOLVE ADVISOR TASK (DBMS_SPM)

CREATE_EVOLVE_TASK

EXECUTE_EVOLVE_TASK

REPORT_EVOLVE_TASK

IMPLEMENT_EVOLVE_TASK

SET_EVOLVE_TASK_PARAMETER

AUTO EVOLVE TASK PARAMETERS

SQL MANAGEMENT BASE ENHANCEMENT

In Oracle 12C plan rows are persisted to sysaux

tablespace, so when

dbms_xplan.display_plan_baseline is run, you

fetch plan data from SMB rather than compiling

the sql statement with baseline.

Planning an upgrade ?

UPGRADING STRATEGY

Before upgrade pack 10g plans into STS

After upgrade load plans from STS to SPM

Use 10G Statistics until the system is stable

Use pending statistics feature

Alternatively export stats from prod and import them in test

After upgrade and before stats gather switch on incremental stats for all partitioned tables

MIGRATING FROM STORED OUTLINES

TEST SQL’S WITHOUT HINTS

_OPTIMIZER_IGNORE_ HINTS to TRUE

CREATE STS FROM TRACE FILE

SPM and SQL Tuning Advisor

SPM & Adaptive Plans

SPM and Adaptive Cursor Sharing

SPM and Stored Outlines

BUG 11719151 SPM CAPTURE CAUSES

SLOWNESS

Confirmed Version affected 11.2.0.2

Waits for "library cache: mutex X“

Merge slow over following tables :-

sqlobj$ , sqlobj$data, or sqlobj$auxdata

Issue is fixed in 11.2.0.3 (Server Patch Set)

SYSAUX TABLESPACE SPACE ISSUES

(Doc ID 287679.1)

BEST PRACTICES FOR EXECUTION PLANS

When upgrading use STS for loading plans in SPM

Gather stats after data is loaded & before indexes are created

Parallel execution should be leveraged

Use pending stats feature to minimize risk

Export statistics from PROD and import them to TEST

Get all good plans in STS and accept them all

Upgrade to 12C to leverage adaptive plans and many more

Review the plan evolution report for critical SQL’s

THANK YOU

What is the default retention period for plans in

SMB ?

SMB (SQL Management Base) uses system

tablespace for its repository.

True or False

Automatic plan evolution of SPM is part of the

Tuning Pack ?

True or False

We can use report_evolve_task function to

display results of evolve task ?

True or False