Kellyn Pot’Vin, Sr. Technical Consultant

How to Dive in Fast and Find the Right

Answer to the Big Questions

A Little About Me:

ACE Director, Oak Table Member

Board of Directors for RMOUG

Conference Director for RMOUG

DB Track Lead for KSCOPE

Author and presenter at Oracle

Open World, HotSos, Collaborate,

KSCOPE and others…

Advocate for Women in Technology

Lives in Westminster, CO!

Bit of a Change

What do I get questions on?

Work Smart, Don’t Work Hard…

ASH/AWR Reports in EM12c

Compare ADDM

SQL Monitor

ASH/AWR Reporting from the Command

Line

Search SQL, (Least Used Feature of EM)

ASH Queries

The Road Trip

Where do you want to go?

How will you get there?

Cool….

Where You End up…

Stay on the Right Road

Optimization- Tune for Time or You’re

Wasting Time.

Know Your Goal(s)

Set a Stopping Point, avoid OTD,

(Obsessive Tuning Disorder)

Do NOT Assume. Always do the

Research and Have Data.

Brief History

ASH= Active Session History

AWR= Automatic Workload Repository

Introduced in Oracle 10g

Evolution to statspack, requests for performance reporting improvements.

“Always on” approach to performance metrics with requirement of non-locking collection process.

Requires Management Diagnostic Pack License from Oracle.

The Location in EM12c For Some

of Today’s Presentation…

Running ASH Report from EM

• ASH is by time, not snapshot.

• Set start date and time.

• End date and time

• Generate report

HTML Format ASH

Main ASH Info

Top SQL, Top Sessions

Top SQL Details

Top Parallel, Top DB Files

How Often Are We Asked, “What

Changed?”

It ran fine last week, now it doesn’t!

ETL loads have changed, but no one

has released any new code!

The DBA says there hasn’t been any

parameter changes to this database, but

I’m sure there have been.

Compare ADDM Resolution

What is Compare ADDM?

Uses Two AWR snapshots

Creates Report that-

Compares SQL that is common and

different.

SGA changes

IO/CPU bound issues

Parameter Changes

What is in an ADDM Compare?

Report Includes Following: Clear Demonstration of impact of change.

Recommendations to address issue.

Identifies causes behind change, (with limitations.)

Lists Regressed SQL, too!

Tip: If Installing to database for first time, (simple installation, nothing to concern about, just pkg to fulfill views) you must have preferred credentials SET of install will fail!

Executing a Report from EM12c

Choose focus period

Choose to compare to an Offset,

Baseline or Custom

2-3PM, 12th Vs. 13th

Familiar interface with visual wait event

comparisons.

Average # of sessions during each

period are displayed.

Detail Report

High level data, highlight for analysis

and recommendations.

Regression SQL

Any performance degradation is noted

with the down arrow icon:

Top Segments Causing IO Waits

High Level data

Click on “Show Hot Object Breakdown”

to see more detail.

Resource Comparisons

Comparisons of Memory, CPU, IO and

Interconnect.

Memory Is there Virtual paging?

Memory Base Period

Memory Comparison Period

Dashboard Provided for CPU,

Memory, IO and Interconnect

Is something OTHER than Oracle the

cause?

IO Bound Dashboard

Base vs. comparison period

Temp reads/writes specified

Single block read latency

SQL Monitor, EM12c Style

One More way to identify performance

issues.

Monitoring view ease for those less

familiar with database performance.

SQL Monitor Dashboard

Status of Statement

Wait Events

Degree of

Parallelism

SQL_ID

SQL Text

Exadata and Offloading

Drill down to specific statement within

SQL Monitor will display offload

efficiency per statement.

Full Detail of SQL Execution

View Report

SQL Monitor Report CLI

SET LONG 1000000

SET LONGCHUNKSIZE 1000000

SET LINESIZE 1000

SET PAGESIZE 0

SET TRIM ON

SET TRIMSPOOL ON

SET ECHO OFF

SET FEEDBACK OFF

SELECT DBMS_SQLTUNE.report_sql_monitor(

sql_id => '5vh6y3b7tnv8r',

type => 'TEXT',

report_level => 'ALL') AS report

FROM dual;

Text Output of SQL Monitor

One of the Best & Least Used

Features in EM

Search SQL

Problem Query

We Have the SQL_ID, What Next?

4v2tsp8dz0nhn is our SQL_ID

Go to the EM Console, (Example is

EM12c)

Search SQL Interface

Choose AWR Snapshots, (change Time

Period), AWR Baselines and put

SQL_ID

Click on Search

SQL_ID link for SQL Details

Split up by tabs for Cursor, AWR,

Baselines and SQL Tuning Sets

Plan Hash Value

Elapsed Time

AWR Data

Snapshot IDs

Click on Snapshot ID and gather

valuable data on resource usage during

snapshot time or choose to view report.

AWR Report or Run ADDM Report

AWR and ASH from the CLI

All DBAs should know how to do this!

Running Reports, Command Line

$ORACLE_HOME/rdbms/admin/awrrpt.sql;

$ORACLE_HOME/rdbms/admin/ashrpt.sql;

$ORACLE_HOME/rdbms/admin/awrsqlrpt.sql; Less Known AWR Reports:

awrinfo.sql General AWR Info

awrddrpt.sql Comparison report between snapshots

awrblmig.sql Migrates pre-11g baseline data into 11g Baseline tables.

awrgrpt.sql RAC Aware AWR Report.

AWR Info Report

Snapshot Interval Information

Basic Info on Instances and Nodes

No User or Application Schema info.

Space Usage by SYSAUX

WRH$ and Non- AWR Objects, ordered

by size

Snapshot info and if any errors.

Advisor Tasks

AWR Info Report

ASH Info Report @$ORACLE_HOME/rdbms/admin/awrrpt.sql;

-Report Format: Text or HTML

-Days to view snapshot IDs

-Beginning and Ending Snapshot ID’s

- Name of Report

ASH Report @$ORACLE_HOME/rdbms/admin/ashrpt.sql;

-Report Format: Text or HTML.

-Timestamp to being report from.

-Duration in minutes.

-Name of report.

SQL_ID Specific AWR Report

“Interesting Part”

Finale!

Select * from table(dbms_xplan.display_awr(‘43mp3mjufgnkg’));

Querying ASH Data Directly

More defined reporting

No need to pull full report

Detail on waits that are of interest

Join to non-AWR objects

Examples and Ideas…

V$ACTIVE_SESSION_HISTORY

SAMPLE_ID- This is a unique identifier within an ASH sample.

SAMPLE_TIME- A unit of time used by Active Session History, (not to be confused with DB_TIME)

USER_ID- Identifier for a user that’s executing the session.

SESSION_ID- Same as the SID or Session ID and can be used to join to SID in other views/tables.

SESSION_STATE- What was the state of the session when ASH recorded the sample.

ON CPU/WAITING- The two session states in Active Session History. ON CPU is active, vs. Waiting, which is self-explanatory.

EVENT- Type of event that the session is currently active or waiting on.

TIME_WAITED- How long the session has been waiting if waiting.

WAIT_TIME- Confusing- but this is populated by any wait time if the session is currently active and for the previous waits.

SQL_ID- The unique identifier for the SQL statement being executed.

SQL_CHILD_NUMBER-The cursor child number.

Session Averages

select

ROUND(RATIO_TO_REPORT(SUM(1)) OVER () * 100 ,2) PERCENTAGE,

ash.session_type SESS_TYPE,

session_state STATUS,

decode(nvl(sql_id,'-1'),'-1','nonsql','sql') SQL_TYPE,

count(distinct to_char(session_id)|| to_char(session_serial#)) SESS_CNT

from v$active_session_history ash

where

sample_time > sysdate - 30/(24*60)

and (

( ash.session_state = 'ON CPU' )

or

( ash.session_type != 'BACKGROUND' )

)

group by

ash.session_type,

ash.session_state, decode(nvl(sql_id,'-1'),'-1','nonsql','sql')

order by count(*)

/

Session Avg. Output

Note the % of Background processes

Inspecting What col type for a20

select * from (select

ash.SQL_ID , ash.SQL_PLAN_HASH_VALUE Plan_hash, aud.name type,

sum(decode(ash.session_state,'ON CPU',1,0)) "CPU",

sum(decode(ash.session_state,'WAITING',1,0)) "WAITING",

sum(decode(ash.session_state,'WAITING', decode(wait_class, 'User I/O',1,0),0)) "IO

WAIT" ,

sum(decode(ash.session_state,'WAITING', decode(wait_class, 'User I/O',1,0),0)) "IO" ,

sum(decode(ash.session_state,'WAITING', decode(wait_class, 'Concurrency',1,0)))

"CONCURRENCY" ,

sum(decode(ash.session_state,'WAITING', decode(wait_class, 'Application',1,0)))

"Application" ,

sum(decode(ash.session_state,'ON CPU',1,1)) "TOTAL"

from v$active_session_history ash,

audit_actions aud

where SQL_ID is not NULL

and ash.sql_opcode=aud.action

and ash.sample_time > sysdate - &minutes /( 60*24)

group by sql_id, SQL_PLAN_HASH_VALUE , aud.name

order by sum(decode(session_state,'ON CPU',1,1)) desc

) where rownum < 5;

10 Min. View of Waits by SQL_ID

Choose Time in Minutes To Review, (10

in our example)

SQL_ID and Plan Hash Value Shown

Waits for CPU, Wait, IO Wait and others.

Quantity of Events Occurred Over

Small Amounts of Time Col event for a50

select event, count(1)

from v$active_session_history

where sample_time between

to_date('21-FEB-14 01.43.00 PM','dd-MON-yy hh:mi:ss PM')

and

to_date('21-FEB-15 01.53.00 PM','dd-MON-yy hh:mi:ss PM')

group by event

order by event;

Results, Where to Focus?

Transaction Wait Detail col event for a22

col block_type for a18

col objn for a18

col otype for a10

col fn for 99

col sid for 9999

col bsid for 9999

col lm for 99

col p3 for 99999

col blockn for 99999

select

to_char(sample_time,'HH:MI') st,

substr(event,0,20) event,

ash.session_id sid,

mod(ash.p1,16) lm,

ash.p2,

ash.p3,

nvl(o.object_name,ash.current_obj#) objn,

substr(o.object_type,0,10) otype,

CURRENT_FILE# fn,

CURRENT_BLOCK# blockn,

ash.SQL_ID,

BLOCKING_SESSION bsid

from v$active_session_history ash,

all_objects o

where event like 'enq: TX%'

and o.object_id (+)= ash.CURRENT_OBJ#

and sample_time > sysdate - 10/(60*24)

Order by sample_time

Transaction Lock Output

What TX row locks are occurring!

Knowing What’s in the ASH

Buffer

• Deters from making assumptions on what data is being

queried.

• Know your samples!

Wait Events Across Nodes

Query top

10

SQL_ID’s

in the last

10

minutes?

SQL_ID and CPU Usage

IO Waits by Object from ASH

SQL Text with ASH

• SQL for most recent five minutes of sample data from ASH

SQL Results • SQL_ID, SQL Text, Sample Time that Process was captured

in.

Average Activity- Graphed

Formatting and Setup accept hours prompt "hours (default 12) : " default 12

column f_hours new_value v_hours

select &hours f_hours from dual;

column f_secs new_value v_secs

column f_samples new_value samples

select 3600 f_secs from dual;

select &v_secs f_samples from dual;

--select &seconds f_secs from dual;

column f_bars new_value v_bars

select 5 f_bars from dual;

column aas format 999.99

column f_graph new_value v_graph

select 30 f_graph from dual;

column graph format a30

column total format 99999

column npts format 99999

col waits for 99999

col cpu for 9999

select

to_char(to_date(tday||' '||tmod*&v_secs,'YYMMDD SSSSS'),'DD-MON HH24:MI:SS') tm,

samples npts,total/&samples aas,

substr(substr(substr(rpad('+',round((cpu*&v_bars)/&samples),'+') ||

rpad('-',round((waits*&v_bars)/&samples),'-') ||

rpad(' ',p.value * &v_bars,' '),0,(p.value * &v_bars)) ||

p.value || substr(rpad('+',round((cpu*&v_bars)/&samples),'+') ||

rpad('-',round((waits*&v_bars)/&samples),'-') ||

rpad(' ',p.value * &v_bars,' '),(p.value * &v_bars),10) ,0,30)

,0,&v_graph)graph,total,cpu, waits

from (

select to_char(sample_time,'YYMMDD')tday

, trunc(to_char(sample_time,'SSSSS')/&v_secs) tmod

, sum(decode(session_state,'ON CPU',1,decode(session_type,'BACKGROUND',0,1))) total

, (max(sample_id) - min(sample_id) + 1 ) samples

, sum(decode(session_state,'ON CPU' ,1,0)) cpu

, sum(decode(session_type,'BACKGROUND',0,decode(session_state,'WAITING',1,0))) waits

/* for waits I want to subtract out the BACKGROUND

but for CPU I want to count everyon */

from v$active_session_history

where sample_time > sysdate - &v_hours/24

group by trunc(to_char(sample_time,'SSSSS')/&v_secs),

to_char(sample_time,'YYMMDD')

union all

select to_char(sample_time,'YYMMDD')tday

, trunc(to_char(sample_time,'SSSSS')/&v_secs) tmod

, sum(decode(session_state,'ON CPU',10,decode(session_type,'BACKGROUND',0,10))) total

, (max(sample_id) - min(sample_id) + 1 ) samples

, sum(decode(session_state,'ON CPU' ,10,0)) cpu

, sum(decode(session_type,'BACKGROUND',0,decode(session_state,'WAITING',10,0))) waits

/* for waits I want to subtract out the BACKGROUND

but for CPU I want to count everyon */

from dba_hist_active_sess_history

where sample_time > sysdate - &v_hours/24

and sample_time < (select min(sample_time) from v$active_session_history)

group by trunc(to_char(sample_time,'SSSSS')/&v_secs),

to_char(sample_time,'YYMMDD')) ash, v$parameter p

where p.name='cpu_count'

order by to_date(tday||' '||tmod*&v_secs,'YYMMDD SSSSS')

/

Pivot the Wait Events

Digging into History

DBA_HIST_ACTIVE_SESS_HISTORY

SNAP_ID

SAMPLE_ID

SAMPLE_TIME

SESSION_ID

USER_ID

SQL_ID

WAIT_CLASS

SESSION_STATE

PGA_ALLOCATED

Process Information

SELECT * FROM (

SELECT /*+ PARALLEL */

count(*) AS count,

user_id, program, module, sql_id

FROM SYS.DBA_HIST_ACTIVE_SESS_HISTORY

WHERE sample_time > TO_DATE('19-FEB-2014 03.00.00 PM','dd-MON-yy hh:mi:ss PM')

AND sample_time < TO_DATE('19-FEB-2014 08.00.00 PM','dd-MON-yy hh:mi:ss PM')

AND program LIKE 'oracle@%'

GROUP BY user_id, program, module, machine, sql_id

ORDER BY count(*) desc

)

WHERE rownum <= 20

/

Results of Process History

Tyler Muth ASH Mining Query

ASH Mining Output

Additional Options:

• Physical Read Averages

• Physical Writes, (Max/Averages)

• Redo Info

• Login Info

• Hard Parsing, etc.

Best Practice When Querying

ASH Data Keep it Simple and don’t reinvent the

wheel.

Samples are an alias for time, not for counts.

Understand what is valuable and compare to packaged reports.

Be aware on RAC of node specific data.

Take care when querying Obj#, File# and Block#, (still issues in different versions…)

Check the time that is available in buffer, don’t assume!

AWR/ASH Links/Blogs

Tyler Muth: http://tylermuth.wordpress.com/

Kyle Hailey, John Beresniewicz, Graham Wood: http://ashmasters.com/

Mine- “For the Love of ASH and AWR” http://dbakevlar.com/2011/02/for-the-love-of-awr-and-ash/

Karl Arao- http://karlarao.tiddlyspot.com/

Guy Harrison- http://guyharrison.squarespace.com/opsgsamples/

Connect with me-