SQL  Elapsed  Time  Analysis  

Unit of Work Time Based

Analysis

Craig A. Shallahamer Founder - OraPub, Inc.

craig@orapub.com

SQL  Elapsed  Time  Analysis  

OraPub is about Oracle performance.

•  OraPub is all about Oracle performance management; systematic and quantitative firefighting and predictive analysis.

•  Web site started in 1995 and the company was founded in 1998 by Craig Shallahamer.

•  OraPub has always been about disseminating Oracle database centric technical information.

•  Consulting, training, books, papers, and products are now being offered.

•  We have been on-site in 24 countries and our resources have been received in probably every country where there are DBAs.

•   Training  •   Unique  Blog  •   Free  Tools  

•   Free  Papers  •   Books  

•   Products  •   Consul8ng  

Resources  

SQL  Elapsed  Time  Analysis  

Short resume...kind of... •  Studies economics, mathematics, and computer science at

university in California, US. •  Started working with Oracle technology in 1989 as a Forms 2.3

developer on Oracle version 5. •  Soon after started performance firefighting...daily! •  Co-found both Oracle’s Core Technology and System

Performance Groups. •  Left Oracle to start OraPub, Inc. in 1998. •  Authored 24 technical papers and worked in 24 countries. •  Authors and teaches his classes Oracle Performance

Firefighting, Adv Oracle Performance Analysis, and Oracle Forecasting & Predictive Analysis.

•  Authored the books, Forecasting Oracle Performance and Oracle Performance Firefighting.

•  Oracle ACE Director. •  Frequent blog contributor: A Wider View

SQL  Elapsed  Time  Analysis  

My two books...

OraPub  discount  code:  IS11  

SQL  Elapsed  Time  Analysis  

Performance analysis philosophies. •  Ratio Analysis is the traditional method relying on simple

calculations leading one to the problem area. “When the ratios are right, then so is performance.”...not always!

•  Wait Event Analysis (WEA) listens to where Oracle says it’s not consuming CPU resources. “When I bring down the top wait event, users are happier.” ...not always!

•  Time Based Analysis (TBA) is centred on interval time, elapsed time, and quantifying the users’ experience, at least in part. TBA is relative to ones perspective and should include CPU time. “When total time is decreases, performance increases.”...not always!

•  Unit of Work Time Based Analysis unites Oracle TBA with Operations Research by creatively using the time it takes to process a single unit of work. The benefits are a deep understanding of cause and effect, solution comparison and evaluation, anticipating performance, complete analysis quantification, and enhanced visuals. “When LIO RT decreases, LIO dependent elapsed times also decrease until the workload increases too much.”

SQL  Elapsed  Time  Analysis  

Situation, over a time interval(s).

Non-Idle Wait Time

CPU Time

Other

IO

Srvr Prc

BG Prc

Time related to all the work occurred for a

specific period of time.

Source: Confio Software’s Igniter product.

Perhaps 1.8M PIOs occurred during this interval.

SQL  Elapsed  Time  Analysis  

Representing time associated with a single unit of work.

If  1.8M  PIOs  occurred  during  a  one  hour  interval  and  there  was  3500  seconds  of  associated  CPU  and  non-­‐idle  wait  Lme,  

then  on  average,  each  PIO  took  1.94  ms  to  complete.  

 

SQL  Elapsed  Time  Analysis  

Contrasting RT based approaches

Non-­‐Idle  Wait  Time  1500s  Total  

Response  Time  3500s  

CPU  Time  2000s  

Focus:  “This  is  what  occurred.”  “This  is  what  we  should  

do.”  

Focus:    “This  is  what  we  can  expect  this  

soluLon  to  do.”  “This  is  the  elapsed  Lme  change.”  

SQL  Elapsed  Time  Analysis  

Classic  Performance  MathemaLcs  

Fully  QuanLfied  

ORTA  

Key  Parameter  DerivaLon  

Proposed  SoluLons  

Performance  Model  

ObjecLve  SoluLon  Analysis  

Poor  Performing  System  

SQL  Elapsed  Time  Analysis  

First, plot a performance situation.

SQL  Elapsed  Time  Analysis  

Second combine respected disciplines.

Rt:cpu =St

1− StλM

⎛⎝⎜

⎞⎠⎟M

SQL  Elapsed  Time  Analysis  

Third, objectively evaluate.

SQL  Elapsed  Time  Analysis  

Keep it as simple as possible. Detail  how  to  move  from  

red  to  blue…  

Provide  just  enough  informaLon  to  get  your  point  across  and  saLsfy  your  audience.  

SQL  Elapsed  Time  Analysis  

Situation, time per work unit.

Time  related  to  compleLng  a  single  unit  of  work.  

Graph created using OraPub’s RT Graph

Template.

SQL  Elapsed  Time  Analysis  

Moving: interval time to RT analysis. •  Notice the focus change: From total interval time, to time per unit of

work. •  Situation. Over a 30 minute interval, 5000 PIOs occurred, 250

seconds of CPU was consumed, and sessions waited for 2000 seconds. Key performance areas degraded as PIOs increased.

•  Unit of work. We must choose an appropriate unit of work. (e.g., physical IO read requests)

•  Service Time. How much CPU is consumed per unit of work. (e.g., 250 sec / 5000 pio = 0.050 sec/pio)

•  Queue Time. How much non-idle wait time per unit of work. (e.g., 2000 sec / 5000 pio = 0.400 sec/pio)

•  Arrival Rate. How much work arrives per unit of time. (e.g., 5000 pio / 1800 sec = 2.778 pio/sec)

•  Response Time. Simply, service time plus queue time. (e.g., 0.050 sec/pio + 0.40 sec/pio = 0.45 sec/pio)

SQL  Elapsed  Time  Analysis  

Creating the RT graph using M-Solver.

http://filezone.orapub.com/cgi-bin/msolve.cgi!

SQL  Elapsed  Time  Analysis  

All the key parameters

are now available to

create a clean RT

graph, plus the M-Solver

details.

SQL  Elapsed  Time  Analysis  

Got the

graph!

SQL  Elapsed  Time  Analysis  

Reality Check: A clear RT curve.

SQL  Elapsed  Time  Analysis  

Reality Check: A clear RT curve.

SQL  Elapsed  Time  Analysis  

Reality Check: Production system.

source: http://aberdave.blogspot.com/2011/03/response-time-analysis-based-on-awr.html!

SQL  Elapsed  Time  Analysis  

Reality  Check:  Altering  insert  batch  size  

Batch  size  1  

Batch  size  2  

28%!

More? http://shallahamer-orapub.blogspot.com/2010/05/insert-batch-size-performance-effects.html!

work: insert!time: ms!

SQL  Elapsed  Time  Analysis  

In summary…step by step. •  Perform an Oracle response time analysis (ORTA). •  Pick a good workload metric. •  Gather the total workload. •  Calculate the key and classic performance

parameters. •  Plot single point. •  Create response time curve by combining

performance situation with classic performance mathematics.

•  Objectively and scientifically compare alternative solutions!

SQL  Elapsed  Time  Analysis  

Let’s Do It!

http://filebank.orapub.com/perf_stats/SP_PDXPROD.txt!

SQL  Elapsed  Time  Analysis  

Want to dig deeper? •  Craig’s Blog – A W i d e r V i e w •  Paper: Evaluating Alternative Performance Solutions

•  Training from OraPub

–  Oracle Performance Firefighting (I)

–  Adv Oracle Performance Analysis (II)

•  Books

–  Oracle Performance Firefighting (C. Shallahamer)

•  Chapter 9 is FREE to download

Melbourne  &  Perth  in  Q2  2012  

SQL  Elapsed  Time  Analysis  

Thank You!