The Need For Speed - tapoueh.org · Premature optimization is the root of all evil ... Premature...

The Need For Speedleads to PostgreSQL

Dimitri Fontaine dimitri@2ndQuadrant.fr

28 Mars 2013

Dimitri Fontaine dimitri@2ndQuadrant.fr The Need For Speed 28 Mars 2013 1 / 23

Dimitri Fontaine

2ndQuadrant FrancePostgreSQL Major Contributor

pgloader, prefix, skytools, debian, . . .

CREATE EXTENSION

CREATE EVENT TRIGGER

Bi-Directional Replication

Partitionnement

Performances

Optimisation SQL

Quelques experiences d’optimisations

Optimisation de requetes

Migration Oracle, de 1h30 a 5mins

prefix, GiST indexing

pgloader

preprepare

Extract Month From date, THE HORROR

Certaines requetes SQL sont assez faciles a optimiser.

select f1, f2, f3, d

from t

where extract(’month’ from t.d)

= extract(’month’ from now())

Extract Month From date, THE HORROR

Ah, tiens, un index !

select f1, f2, f3, d

from t

where t.d >= date_trunc(’month’, now())

and t.d < date_trunc(’month’, now())

+ interval ’1 month’

Performance Club

http://fetter.org/optimization.html

1 The first rule of Optimization is, you do not talkabout Optimization.

2 The second rule of Optimization is, you DO NOTtalk about Optimization.

3 If your app is running faster than the underlyingtransport protocol, the optimization is over.

4 One factor at a time.

5 No marketroids, no marketroid schedules.

6 Testing will go on as long as it has to.

7 If this is your first night at Optimization Club, youhave to write a test case.

Performance Club

http://fetter.org/optimization.html

1 The first rule of Optimization is, you do not talkabout Optimization.

2 The second rule of Optimization is, you DO NOTtalk about Optimization.

3 If your app is running faster than the underlyingtransport protocol, the optimization is over.

4 One factor at a time.

5 No marketroids, no marketroid schedules.

6 Testing will go on as long as it has to.

7 If this is your first night at Optimization Club, youhave to write a test case.

Premature optimization is the root of all evil

Donald Knuth, Structured Programming with go to Statements

“Programmers waste enormous amounts of

time thinking about, or worrying about, thespeed of noncritical parts of their programs,and these attempts at efficiency actually havea strong negative impact when debugging andmaintenance are considered. We should forgetabout small efficiencies, say about 97% of thetime: premature optimization is the root of allevil. Yet we should not pass up ouropportunities in that critical 3%.”

La performance : quand s’y interesser ?

Premature optimization is the root of all evil

Jamais trop tot

Avant qu’il ne soit trop tard

Preparation d’une phase de croissance

Reduction des depenses energetique

Reduction de la facture d’hebergement

Meilleur service aux utilisateurs

Diminishing Returns

Loi des rendements decroissants

Plus tu pedales moins vite, moins plusvite tu avances

Maıtriser l’effort d’optimisation

Difficulte de savoir quand on est alleassez loin

Prendre du recul sur ce que l’on fait

La performance dans quel but

http://www.copyblogger.com/website-speed-matters/

A one second delay in page-load can cause 7%loss in customer conversions.

If you make $1,000 a month from your site —that’s seventy bucks a month you are losing —and $840 a year. Can you afford to just throwaway $70 a month? $840 a year?

La performance c’est quoi ?

Ameliorer les performances ne peut se faire qu’apres avoir profile

Loi d’Amdahl

profiling

metrologie

Mesurer les performances

EXPLAIN

EXPLAIN (VERBOSE, BUFFERS, ANALYZE)

\timing

Attention aux allers retours entre client et serveur

Round-trip

Bande passante (bandwidth)

Comment ameliorer les performances

Premier reflexe : ne pas executer la requete !

Traitements par lots (batch)

Traitements hors lignes (asynchrone)

LISTEN et NOTIFY

Outils d’anlyze des performances des requetes 1/2

Analyzer les performances

EXPLAIN

(ANALYZE, VERBOSE, BUFFERS)

INSERT, DELETE, UPDATE

(ne pas oublier de ROLLBACK)

Outils d’anlyze des performances des requetes 2/2

Analyzer les performances

Un mot sur les Nested Loops

http://explain.depesz.com/

SELECT * FROM pg locks;

pg activity

Optimisation

Les approches essentielles

Identifier les requetes

Reecrire les requetes

Traiter moins de donnees

Revoir les Types de donnees

Revoir l’utilisation des indexes

Utiliser des tableaux

WITH et OFFSET

Optimisation

WITH et OFFSET

Optimisation

WITH et OFFSET

Conclusion

The Need For Speed.

The Need For Speed - tapoueh.org · Premature optimization is the root of all evil ... Premature...

Documents

Performance Analysis: An Introduction to the Tools and ... · •“Premature optimization is the root of all evil.”–Donald Knuth •Optimising code is often time-consuming •Optimised

Princeton University€¦ · Princeton University Computer Science 217: Introduction to Programming Systems “Premature optimization is the root of all evil.” --Donald Knuth “Rules

Thinking about performance€¦ · “Premature optimization is the root of all evil” “We should forget about small efficiencies, say about 97% of the time” Different designs:

Trop craquant

Interactive Theorem Proving (ITP) Course · KISS and Premature Optimisation follow standard design principles I KISS principle I \premature optimization is the root of all evil" (Donald

Trop mignon

TROP CRAQUANTS

" Trop c'est trop! " Conte moderne écologique

Dieu : trop loin et trop abstrait ?

6.172 Systems - MIT OpenCourseWare · Lessons Learned from the 70’s and 80’s : Premature optimization is the root of all evil. [K79] Donald Knuth William Wulf Michael Jackson

Premature Labor

Le cholestérol, trop, c’est trop - SSQ Assurance

Scalable Multi-Purpose Network Representation for Large ... · Premature optimization is the root of all evil { D.E.Knuth A. Legrand (CNRS) INRIA-MESCAL Scalability vs. Accuracy Context

Performance Engineering with Profiling Toolsprogforperf.github.io/Profilingtools.pdf · •“Premature optimization is the root of all evil”- Knuth •Should focus on optimizing

Computer science - Théorie vs expérimentation Partie 3 ... · premature optimization is the root of all evil. D. Knuth 10/47. Ingénierie algorithmique Optimisation de code Exemple

Premature Newborns (Preemies): An Overviewsyracusepediatrics.com/images/Premature Newborn Overview.pdf · Premature Newborns (Preemies): An Overview, continued the information contained

Premature baby

Hear No Evil, See No Evil, Speak No Evil

Premature Delivery Premature Rupture of Membrane Prolonged Pregnancy, Multiple Pregnancy

Populations vulnérables : Trop peu, trop tard ou nouvelle opportunité ?