awr and eyond deep dive, (dont forget · 5/1/2015 · title: how to use the powerpoint template...

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AWR and Beyond Deep Dive, (Don’t Forget EM12c!)

Oracle Confidential 2

Kellyn Pot’Vin-Gorman, Consulting Member of Technical Team, Strategic Customer Program May, 2015


Safe Harbor Statement

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.


Stay on the Path…

• 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 behind findings.


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…


Automatic Workload Repository, (AWR) Reports

• Always on with default intervals of 1hr snapshots and 8 days retention.

• Should have at least 60 days of retained data.

• Desire more? Have an AWR Warehouse.

• Interval increase? Use this during workload testing, otherwise, take a manual snapshot:

EXEC DBMS_WORKLOAD_REPOSITORY.create_snapshot;


AWR Reports Are Best Used For..

• To inspect a database level issues, for both a small window of time to extended window.

• Extensive information in report, knowing HOW to parse through the report to achieve goal is important.

• Via EM12c, the report is offered in HTML format and will be environment aware, (single instance, RAC, Exadata.)

• Different reports available from the command line when running from the $ORACLE_HOME/rdbms/admin directory and can be generated in HTML or TXT format.


Wasting Time….

Rarely is there value in this section. As long is everything contains high percentages, move on.


AWR- Top 10 Foreground

•CPU is expected and should be the majority of time. •CPU processing can be extensive though, (still needs to be investigated) •Anything under 10% commonly is disregarded. •Understand what each wait event definition is


Top SQL

Focus on Elapsed Time, but… Displays Top SQL by: •CPU •IO •Gets •Reads, etc…


Full SQL Statements

Linked from Top SQL Lists in HTML report via SQL_ID links. Quick reference when needed.


SGA “Thrashing”


Why PGA is Important

What is an optimal vs. 1 or (M)ulti-pass executions?


Why Can’t I Achieve 100%??

You shall not pass! (90%, that is… )


Percentages and Amounts of Reads are Important

Top two objects correspond to SQL statements in the top IO and most likely top SQL by elapsed time.


What is a Direct Physical Read?

•Inefficient SQL and objects that have high quantity of row changes involved. •Adds significant pressure in RAC environment, too!


Unoptimized vs. Optimized?

Percentages are very low, (under 10%, which is a good sign for this database!


Initial Transaction Locks

10% rule applies here, too! ALTER TABLE <name> initrans <xx>;


RAC Interconnect Exchange

•Data from V$SYSMETRIC_HISTORY •High Exchange rate can signal and issue.


RAC Cache Interconnect Stats


Transfer Rate Between RAC Nodes


ASH Reports

• Excellent for identifying specific issues in database.

• Identifies not just the top SQL, but code.

• Shows top wait events by sample time.

• Don’t confuse samples with AWR snapshots.

• Should not be used to track # of executions.


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


ASH Report- Use Case @$ORACLE_HOME/rdbms/admin/ashrpt.sql; -Report Format: Text or HTML. -Timestamp to being report from. -Duration in minutes. -Name of report.


“Interesting Part”


Finale!

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


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


SQL_ID Specific AWR Report


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 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 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

select &hours f_hours from dual;

select 3600 f_secs from dual;

select &v_secs f_samples from dual;

select 30 f_graph from dual;

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

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

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.

• Again- 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!


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/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/

• Using AWR Reports: http://dbakevlar.com/2015/01/working-with-awr-reports-from-em12c/

• How to Use an ASH Report: http://dbakevlar.com/2015/02/how-to-use-an-ash-report-and-why/

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

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

http://tylermuth.wordpress.com/

http://tylermuth.wordpress.com/

http://ashmasters.com/

http://ashmasters.com/

http://dbakevlar.com/2011/02/for-the-love-of-awr-and-ash/















http://dbakevlar.com/2015/01/working-with-awr-reports-from-em12c/











http://karlarao.tiddlyspot.com/

http://guyharrison.squarespace.com/opsgsamples/


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awr and eyond deep dive, (dont forget · 5/1/2015 · title: how to use the powerpoint template...

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