IOUG Collaborate 2014 ASH/AWR Deep Dive

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Deep Dive to ASH and AWR with EM12c

Kellyn Pot‟Vin

Consulting Member of Technical Team

Strategic Customer Program


The following is intended to outline our general product

direction. It is intended for information purposes only, and

may not be incorporated into any contract. It is not a

commitment to deliver any material, code, or functionality,

and should not be relied upon in making purchasing

decisions. The development, release, and timing of any

features or functionality described for Oracle‟s products

remains at the sole discretion of Oracle.


Program Agenda

What am I asked about?

Easiest Way to Get the Job Done

– ASH/AWR Reports in EM12c

– Compare ADDM

– Search SQL, (Least known and very valuable tool)

– Top Tricks in EM12c with ASH and AWR


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 Tuning Pack License from Oracle.


Read vs. Write

MMON, MMNL

In Memory vs. written to disk

ASH Architecture

Build and Buffer


Read vs. Write

MMON, MMNL


ASH Architecture

Build and Buffer


Read vs. Write

MMON, MMNL


ASH Architecture

Build and Buffer


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


Beginning and End Time of

Report

How Many Samples

Average # of Sessions

Target information in Report

HTML Format ASH

Report Details


Top 5 Events

12


SQL Top Events

13


Top Row Source

14


Top PL/SQL Procedures

15


Top Sessions

16


Blocking Sessions

17


Parallel Processes

18


Activity Over Time

19


ASH- What have we learned?

Solid information from samples for a time period of activity

Shouldn‟t be used for # of occurrences, as it‟s based on samples.

Excellent reporting on

– Percentage of activity

– SQL information

– Procedural info

– Blocking Sessions

– Activity over time.

20


How Often Do We Ask, “What Changed?”

It ran fine last week, now it isn‟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!


Choose focus period

Choose to compare to an

Offset, Baseline or Custom

Executing a Report from EM12c

Comparison


Familiar interface with visual wait event

comparisons.

Average # of sessions during each period

are displayed.

Main Screen of Comparison

2-3PM, 12th Vs. 13th


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 EventsDegree 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


Available since OEM 10g

Strong, but simple feature to

assist the DBA

4v2tsp8dz0nhn is our SQL_ID

Go to the EM

Console, (Example is EM12c)

We Have the SQL_ID, What’s Next?

Search SQL


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


Running Reports, Command Line

$ORACLE_HOME/rdbms/admin/awrrpt.sql;

$ORACLE_HOME/rdbms/admin/ashrpt.sql;

$ORACLE_HOME/rdbms/admin/awrsqrpt.sql;


Running Reports, Command Line

$ORACLE_HOME/rdbms/admin/awrrpt.sql;

$ORACLE_HOME/rdbms/admin/ashrpt.sql;

$ORACLE_HOME/rdbms/admin/awrsqrpt.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


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

Simple queries presented…


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

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 for the previous waits.

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

SQL_CHILD_NUMBER-The cursor child number.


Session Averagesselect

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 Whatcol 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;


12 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

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


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')


Query Cont.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')

/

73


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

• Logon 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/

Oracle- http://www.oracle.com/technetwork/oem/db-mgmt/db-mgmt-

093445.html

http://tylermuth.wordpress.com/

http://tylermuth.wordpress.com/


















http://www.oracle.com/technetwork/oem/db-mgmt/db-mgmt-093445.html








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IOUG Collaborate 2014 ASH/AWR Deep Dive