Why I Hate Django

Why I Hate Django Cal Henderson

O HAI DjangoCon 2008 2

My happy face DjangoCon 2008 3

DjangoCon 2008 4

2.8 billion photos DjangoCon 2008 5

2.8 billion photos 1 per 2.3 people on earth 9.2 per US resident DjangoCon 2008 6

35k photos/sec >2m photos/min DjangoCon 2008 7

Many thousand pages/sec DjangoCon 2008 8

Scale nerd DjangoCon 2008 9

Serious Language DjangoCon 2008 10

Wordpress Yahoo Mediawiki Facebook DjangoCon 2008 11

Wordpress Yahoo Delicious Digg Mediawiki Facebook DjangoCon 2008 12

Flamework Serious Toolset DjangoCon 2008 13

Flamework Flink Flint Flotos Flinderbox Flictionary Flaux Flops Flag Fleng DjangoCon 2008 14

Why hate Django? DjangoCon 2008 15

What does he even know about Django? DjangoCon 2008 16

Pownce DjangoCon 2008 17

A fucking blogging engine DjangoCon 2008 18

Why all the hate? DjangoCon 2008 19

DjangoCon 2008 20

DjangoCon 2008 21

DjangoCon 2008 22

DjangoCon 2008 23

An attack on several fronts DjangoCon 2008 24

An attack on several fronts The team Python Frameworks DjangoCon 2008 25

Django itself Performance Scalability Maintainability DjangoCon 2008 26

The Team DjangoCon 2008 27

Frameworks DjangoCon 2008 28

Struts DjangoCon 2008 29

Craig McClanahan DjangoCon 2008 30

DjangoCon 2008 31

Exhibit A : Beard DjangoCon 2008 32

But Struts is for suits! DjangoCon 2008 33

The Hot Shit DjangoCon 2008 34

DjangoCon 2008 35

Rails = Badass DjangoCon 2008 36

Instead? A boy band? DjangoCon 2008 37

DjangoCore The Album DjangoCon 2008 38

DjangoCon 2008 39

Also, a wizard Simon “Stinky” Willison DjangoCon 2008 40

Python DjangoCon 2008 41

Trendy Google! DjangoCon 2008 42

But not that trendy DjangoCon 2008 43

But not that trendy It’s no ruby DjangoCon 2008 44

But not that trendy It’s no ruby Or Haskell DjangoCon 2008 45

But not that trendy It’s no ruby Or Haskell Or Erlang DjangoCon 2008 46

But not that trendy It’s no ruby Or Haskell Or Erlang Or Scala DjangoCon 2008 47

Significant Whitespace DjangoCon 2008 48

DjangoCon 2008 49

Salmon DjangoCon 2008 50

Universe of marshy force. Field sense shallows the hatchery saying Hello,. World!. Hydro. Power spring sometimes; snowmelt powers snowmelt always. DjangoCon 2008 51

DjangoCon 2008 52

No quantum superpositions DjangoCon 2008 53

DjangoCon 2008 54

“-”.join(array) DjangoCon 2008 55

Restarting the server? WTF!? DjangoCon 2008 56

WSGIReloadMechanism DjangoCon 2008 57

“I buy my eggs at the cheese shop” - Aaron Straup Cope DjangoCon 2008 58

“I buy my eggs at the cheese shop” ] - Aaron Straup Cope E G A U G N A L N O O [M DjangoCon 2008 59

DjangoCon 2008 60

__import__() from future import awesome DjangoCon 2008 61

Basically, for hippies Scared of real OO languages DjangoCon 2008 62

Frameworks DjangoCon 2008 63

Flamework is a framework But what does that mean? DjangoCon 2008 64

Make common tasks: easier faster error-free DjangoCon 2008 65

Show a list of photos Write an API method Kill all humans DjangoCon 2008 66

Front-tier frameworks Act as glue DjangoCon 2008 67

Other Data store Services Data Model Business Logic Request Interaction Templates Dispatcher Logic Framework Users DjangoCon 2008 68

Great for getting started Slows you down later? What is it doing in there? DjangoCon 2008 69

DjangoCon 2008 70

DjangoCon 2008 71

DjangoCon 2008 72

Fast Easy Scalable Flexible DjangoCon 2008 73

Large scale is often not a good goal DjangoCon 2008 74

Skyscrapers are special DjangoCon 2008 75

Regular houses Don’t need 10 story foundations DjangoCon 2008 76

Just build! DjangoCon 2008 77

DjangoCon 2008 78

DjangoCon 2008 79

DjangoCon 2008 80

Everything here is possible! We care about easy DjangoCon 2008 81

Large Scale DjangoCon 2008 82

No multiple DB clusters DjangoCon 2008 83

Manual partitioning DjangoCon 2008 84

No multiple hosts per DB DjangoCon 2008 85

Where do we read from? DjangoCon 2008 86

How about now? DjangoCon 2008 87

How about now ? DjangoCon 2008 88

Read/write consistency DjangoCon 2008 89

Read/write consistency LAG!!1 DjangoCon 2008 90

Good for non-writing users (logged out) DjangoCon 2008 91

Non time-sensitive data Feeds Read-only APIs DjangoCon 2008 92

DjangoCon 2008 93

Cool kids use master/master pairs DjangoCon 2008 94

Consistent read/write 1. Write to side A 2. Read from side B 3. Replication occurs 4. FAIL DjangoCon 2008 95

Consistent read/write 1. Write to side A 2. Read from side A 3. ??? 4. PROFIT!! DjangoCon 2008 96

Then we can start to get fancy! DjangoCon 2008 97

Where do we read/write? DjangoCon 2008 98

Abstraction FTW db_query($cluster_name, $sql) DjangoCon 2008 99

No sharding DjangoCon 2008 100

WTF is sharding? All about books DjangoCon 2008 101

Dewey Decimal DjangoCon 2008 102

But it can’t do everything DjangoCon 2008 103

Makes some things ‘impossible’ No shard walking DjangoCon 2008 104

DjangoCon 2008 105

Django knows our models It’s possible DjangoCon 2008 106

If we accept constraints DjangoCon 2008 107

No external sequences DjangoCon 2008 108

Auto-incs can be bad master/master shards DjangoCon 2008 109

No automatic denormalization DjangoCon 2008 110

Counters would be easy! DjangoCon 2008 111

And copied fields too DjangoCon 2008 112

High Performance DjangoCon 2008 113

It’s slow! DjangoCon 2008 114

DjangoCon 2008 115

DjangoCon 2008 116

There are limits But they only apply When being really silly DjangoCon 2008 117

Sessions DjangoCon 2008 118

OMG UR ON CRAK DjangoCon 2008 119

Extra DB table A read on every page DjangoCon 2008 120

Lightweight = better DjangoCon 2008 121

Signed cookies DjangoCon 2008 122

No parallelization DjangoCon 2008 123

Multiple cache-requests DjangoCon 2008 124

Multiple multi-keyed reads DjangoCon 2008 125

Slow HTTP requests while we’re doing other stuff DjangoCon 2008 126

Creates dumb SQL DjangoCon 2008 127

foo.exclude(bar = true) WHERE (NOT (bar = 1)) DjangoCon 2008 128

foo.exclude(bar = true) WHERE bar != 1 DjangoCon 2008 129

foo.filter(bar = false) WHERE bar = 0 Indexable! DjangoCon 2008 130

Maintainability DjangoCon 2008 131

Maintainability Awesomeness DjangoCon 2008 132

Verbose template syntax <h1>{{ foo.bar }}</h1> DjangoCon 2008 133

<h1>{{ foo.bar }}</h1> <h1>{$foo.bar}</h1> 3 extra characters! DjangoCon 2008 134

<h1>{{ foo.bar }}</h1> <h1>{$foo.bar|e}</h1> Well almost… DjangoCon 2008 135

{% if edit_mode %} woo {% endif %} {if $edit_mode} woo {/if} 9 extra! DjangoCon 2008 136

Verbose template syntax makes people cry DjangoCon 2008 137

No query debugger DjangoCon 2008 138

>>> from django.db import connection >>> connection.queries [{'sql': 'SELECT polls_polls.id,polls_polls.question,polls_ polls.pub_date FROM polls_polls', 'time': '0.002'}] DjangoCon 2008 139

>>> from django.db import connection >>> connection.queries [{'sql': 'SELECT polls_polls.id,polls_polls.question,polls_ polls.pub_date FROM polls_polls', 'time': '0.002'}] Not good enough! DjangoCon 2008 140

Better, but not amazing DjangoCon 2008 141

DjangoCon 2008 142

Page summary DjangoCon 2008 143

Make it clickable… DjangoCon 2008 144

EXPLAIN is AWESOME DjangoCon 2008 145

And/or show the data DjangoCon 2008 146

MySQL Query Profiler Enough data to choke a whale DjangoCon 2008 147

Not smug enough DjangoCon 2008 148

DjangoCon 2008 149

DjangoCon 2008 150

Unreadable SQL SELECT àpp_userprofile`.ùser_id`,àpp_userprofile`.àccount_status`,àpp_userp rofile`.àccount_status_reason`,àpp_userprofile`.àccount_delete_type`,` app_userprofile`.`syndication_key`,àpp_userprofile`.`blurb`,àpp_userpro file`.`location`,àpp_userprofile`.`country`,àpp_userprofile`.`postal_code`,` app_userprofile`.`gender`,àpp_userprofile`.`theme`,àpp_userprofile`.`tiny _photo`,àpp_userprofile`.`small_photo`,àpp_userprofile`.`smedium_pho to`,àpp_userprofile`.`medium_photo`,àpp_userprofile`.`large_photo`,àp p_userprofile`.òrig_photo`,àpp_userprofile`.`bday_month`,àpp_userpro file`.`bday_day`,àpp_userprofile`.`bday_year`,àpp_userprofile`.ìs_pro`,à pp_userprofile`.`privacy_settings_id`,àpp_userprofile`.èmail_settings_id `,àpp_userprofile`.`preference_settings_id`,àpp_userprofile`.àd_counte r`,àpp_userprofile`.`num_friends`,àpp_userprofile`.`num_fans`,àpp_user profile`.`num_feeds`,àpp_userprofile`.`num_blocked_fans`,àpp_userpro file`.`num_friend_requests`,àpp_userprofile`.`default_set_id`,àpp_userpr ofile`.ìnvite_id`,àpp_userprofile`.ìnvite_round`,àpp_userprofile`.àvail_in vites`,àpp_userprofile`.òriginal_email` FROM àpp_userprofile` WHERE (àpp_userprofile`.ùser_id` = 1) DjangoCon 2008 151

Unreadable SQL SELECT * FROM `app_userprofile` WHERE `user_id` = 1 DjangoCon 2008 152

SELECT * is fast! Faster over the wire Faster to parse Easier to debug DjangoCon 2008 153

Unreadable SQL SELECT àpp_note`.ìd`,àpp_note`.`type`,àpp_note`.`body`,àpp_note `.`sender_id`,àpp_note`.`date_sent`,àpp_note`.`num_recipie nts`,àpp_note`.`recipient_type`,àpp_note`.`set_id`,àpp_not e`.`direct_to_id`,àpp_note`.`media_file_id`,àpp_note`.ùrl`,à pp_note`.ùrl_inline`,àpp_note`.ùrl_clicks`,àpp_note`.èmbe d_id`,àpp_note`.èvent_id`,àpp_note`.ìs_direct`,àpp_note`.` is_public`,àpp_note`.ìs_deleted`,àpp_note`.ìs_ad`,àpp_no te`.`reply_to_id`,àpp_note`.`forwarded_from_id`,àpp_note`.` original_note_id`,àpp_note`.`stars`,àpp_note`.`rsvp` FROM àpp_note` LEFT OUTER JOIN àpp_userprofile_notes` AS `m2m_app_note__recipients` ON àpp_note`.ìd` = `m2m_app_note__recipients`.`note_id` WHERE ((NOT (àpp_note`.ìs_deleted` = True)) AND `m2m_app_note__recipients`.ùserprofile_id` = 17573) ORDER BY àpp_note`.`date_sent` DESC LIMIT 16 DjangoCon 2008 154

Unreadable SQL SELECT n.* FROM app_note AS n LEFT OUTER JOIN app_userprofile_notes AS l ON n.id=l.note_id WHERE n.is_deleted = False AND l.userprofile_id=17573 ORDER BY n.date_sent DESC LIMIT 16 DjangoCon 2008 155

Django makes me scared of joins DjangoCon 2008 156

Actually, JOINs are evil DjangoCon 2008 157

DjangoCon 2008 158

Low version number DjangoCon 2008 159

DjangoCon 2008 160

DjangoCon 2008 161

Suspiciously small Django: 105 klocs Flamework: 260 klocs DjangoCon 2008 162

Suspiciously small Very long lines? DjangoCon 2008 163

Can’t pluralize octopus DjangoCon 2008 164

Commit all fields at once DjangoCon 2008 165

Race conditions! DjangoCon 2008 166

Dirty flags DjangoCon 2008 167

Don’t make Malcolm cry DjangoCon 2008 168

No simple way to inc/dec DjangoCon 2008 169

UPDATE foo SET x=x+1 Makes consistency hard! DjangoCon 2008 170

Character encoding Input validation? DjangoCon 2008 171

Character encoding Input validation? (Probably broken) DjangoCon 2008 172

No mascot!?! DjangoCon 2008 173

Echidna? DjangoCon 2008 174

MAGICAL POWERS DjangoCon 2008 175

No deployment system DjangoCon 2008 176

Extending models Tables are never big enough DjangoCon 2008 177

Model changes manage.py reset appname DjangoCon 2008 178

django-evolution dmigrations DjangoCon 2008 179

What’s django done for you lately? DjangoCon 2008 180

thanks (now go make it better)

Photo credits flickr.com/photos/wilson/18685396/ flickr.com/photos/sharynmorrow/2571566304/ • • flickr.com/photos/uhop/105063089/ flickr.com/photos/florathexplora/286035943/ • • flickr.com/photos/plasticbag/91453376/ flickr.com/photos/webguru4god/2233500779/ • • flickr.com/photos/zenoc/1408162618/ flickr.com/photos/emdot/195189924/ • • flickr.com/photos/subinev/27810058/ flickr.com/photos/kayepants/391645870/ • • flickr.com/photos/kaptainkobold/2531797176/ flickr.com/photos/ppowers/793939285/ • • flickr.com/photos/esti/243781036/ flickr.com/photos/dinesh_valke/425540358/ • • flickr.com/photos/oneras/253617128/ flickr.com/photos/hawkexpress/306276212/ • • flickr.com/photos/josefstuefer/72512671/ flickr.com/photos/cedric1981/383614033/ • • flickr.com/photos/pgoyette/168076182/ flickr.com/photos/macspite/1118042091/ • • flickr.com/photos/paulhammond/2825869449/ flickr.com/photos/jpstanley/1440357613/ • • flickr.com/photos/nez/378348754/ flickr.com/photos/ashclements/248887492/ • • flickr.com/photos/calevans/2265863104/ flickr.com/photos/kecko/1876479840/ • • flickr.com/photos/mbiddulph/416190643/ flickr.com/photos/difusa/131100622/ • • flickr.com/photos/obliterated/2249663391/ flickr.com/photos/amagill/378984660/ • • flickr.com/photos/salim/67753003/ flickr.com/photos/bea_k63w-wa/2466009108/ • • flickr.com/photos/sosalem/2816909110/ flickr.com/photos/namullim/2096115820/ • • flickr.com/photos/radiorover/324193883/ flickr.com/photos/lotterymonkey/175248733/ • • flickr.com/photos/nickwheeleroz/2773776799/ flickr.com/photos/13519089@N03/1380483002/ • • flickr.com/photos/rse/22972901/ flickr.com/photos/gswj/10344097/ • • flickr.com/photos/rougerouge/534615363/ flickr.com/photos/deanj/67607256/ • • flickr.com/photos/hawkexpress/386355092/ flickr.com/photos/malias/2218694639/ • • flickr.com/photos/escalla/438817719/ flickr.com/photos/clintjcl/120760767/ • • flickr.com/photos/mknightphoto/2295688304/ flickr.com/photos/grandpamikey/2228239585/ • • flickr.com/photos/petereed/138369750/ flickr.com/photos/lea/2829752510/ • • flickr.com/photos/superamit/196481424/ • DjangoCon 2008 182

More photo credits flickr.com/photos/simon999/2419051858/ flickr.com/photos/jordanroher/228435564/ • • flickr.com/photos/tonyjcase/2172060723/ flickr.com/photos/tambako/2524829095/ • • flickr.com/photos/heypaul/1428681/ flickr.com/photos/66132721@N00/2725908636/ • • flickr.com/photos/swisscan/2308034084/ flickr.com/photos/freeparking/1279927021/ • • flickr.com/photos/apollonia666/310793656/ flickr.com/photos/drurydrama/1352506223/ • • flickr.com/photos/bdorfman/15846725/ flickr.com/photos/mn_francis/397620193/ • • flickr.com/photos/wishymom/566394520/ flickr.com/photos/dramaqueennorma/273371415/ • • flickr.com/photos/jgarber/121886004/ flickr.com/photos/chasqui/2338990305/ • • flickr.com/photos/eole/380316678/ flickr.com/photos/cityhunter12/2574288725/ • • flickr.com/photos/917press/1940509163/ flickr.com/photos/akbuthod/1508537255/ • • flickr.com/photos/wallyg/476718069/ flickr.com/photos/nunoforos/2811186142/ • • flickr.com/photos/biwook/390088839/ flickr.com/photos/marcusjb/432600086/ • • flickr.com/photos/bdjsb7/1674027307/ flickr.com/photos/12495774@N02/2405297371/ • • flickr.com/photos/naveenroy/314965221/ flickr.com/photos/larimdame/572477975/ • • flickr.com/photos/wyldkyss/2757474674/ flickr.com/photos/harryharris/1525946537/ • • flickr.com/photos/orinrobertjohn/409812627/ flickr.com/photos/davemorris/91808851/ • • flickr.com/photos/candiedwomanire/1651870/ flickr.com/photos/aplumb/121285138/ • • flickr.com/photos/dalvenjah/408497650/ flickr.com/photos/peebot/825451566/ • • flickr.com/photos/krikit/2657457178/ flickr.com/photos/reillyb/2216541900/ • • flickr.com/photos/w5nyv/2370344/ flickr.com/photos/steffe/423086866/ • • flickr.com/photos/jordanfischer/72510316/ flickr.com/photos/ciordia/255983919/ • • flickr.com/photos/tedsblog/91531710/ flickr.com/photos/wwworks/2472230611/ • • flickr.com/photos/celesterc/1069893367/ flickr.com/photos/pnoid00/1909096140/ • • flickr.com/photos/spacematters/766372252/ flickr.com/photos/jurvetson/2229899/ • • flickr.com/photos/esti/147733640/ flickr.com/photos/foxypar4/766801643/ • • flickr.com/photos/rbp/2833593771/ flickr.com/photos/wizardhere/2413404079/ • • DjangoCon 2008 183

these slides are online: iamcal.com/talks DjangoCon 2008 184

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Why I Hate Django

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