Recently I generated a list of the top 200 most viewed pages (URLs) on Wikimedia sites during May-October 2015 from pageview_hourly.[1] It turns out that lot among them - 24 of 200 - contain "�"s in their page name.
"�" is the Unicode [[https://en.wikipedia.org/wiki/Specials_(Unicode_block)#Replacement_character|replacement character]], "most commonly seen when a font does not contain a character, but is also seen when the data is invalid and does not match any character". It is actually disallowed in page names ([[https://en.wikipedia.org/wiki/%EF%BF%BD | "bad title"]]), so something is clearly wrong here either with how these views are recorded (hence filing this bug under Analytics) or with requests that readers' browsers send to our sites (hence the LangEng tag).
Wikipedias in non-Latin languages like Russian and Japanese seem most affected, but it happens on the English WIkipedia too, for example.[2]
Views recorded for these page names are well distributed geographically [3] and across operating systems [4], so it's very unlikely that this is just a few unrecognized spiders running amok, and it seems these numbers do correspond to human reader activity somehow. On the other hand, their rate has varied a lot in the time since May:
{F2921047, size=full}
(Query:[5])
Or in a log scale:
{F2921050, size=full}
On June 3, 2015 for example, page names with "�" made up more than 8% of total non-spider views.
It looks like these spurious views are fairly even distributed among external, internal and unknown referrers[6], so we can also rule out that they are just caused by malformed external links.
I'm also quite certain it's **not a problem with how the page titles were retrieved from the database** on Hive. That was my first thought, but after trying with various access methods (using Hue, the Hive CLI outputting to a terminal and to a file, the new Beeline CLI - which I erroneously conjectured to work fine on #wikimedia-analytics, because I had happened to test a date range and project without anomalous results with Beeline) and looking at the distribution of pageviews, I think that that possibility can be ruled out.
**Footnotes**
```
name=[1]: top 200 May 1-Oct 23 2015.txt, lines=12
SELECT CONCAT('https://',project,'.org/wiki/',page_title), SUM(view_count) AS views
FROM wmf.pageview_hourly
WHERE
year = 2015
AND agent_type = "user"
GROUP BY project, page_title
ORDER BY views DESC LIMIT 200;
https://en.wikipedia.org/wiki/Main_Page 3950733770
https://de.wikipedia.org/wiki/Wikipedia:Hauptseite 518079768
https://en.wikipedia.org/wiki/Special:Search 412911496
https://es.wikipedia.org/wiki/Wikipedia:Portada 301576053
https://it.wikipedia.org/wiki/Pagina_principale 294084319
https://fr.wikipedia.org/wiki/Wikipédia:Accueil_principal 271889431
https://ru.wikipedia.org/wiki/Заглавная_страница 235694286
https://en.wikipedia.org/wiki/- 169453279
https://pt.wikipedia.org/wiki/Wikipédia:Página_principal 109785321
https://id.wikipedia.org/wiki/Template:AdvancedSiteNotices/ajax 89707047
https://en.wikipedia.org/wiki/Special:RecentChanges 89328332
https://de.wikipedia.org/wiki/Spezial:Suche 76612196
https://en.wikipedia.org/wiki/Angelsberg 74498022
https://ja.wikipedia.org/wiki/メインページ 68849608
https://nl.wikipedia.org/wiki/Hoofdpagina 65984206
https://es.wikipedia.org/wiki/Especial:Buscar 65366727
https://fi.wikipedia.org/wiki/Wikipedia:Etusivu 57095356
https://zh.wikipedia.org/wiki/Wikipedia:首页 47913120
https://uk.wikipedia.org/wiki/Template:AdvancedSiteNotices/ajax 46411452
https://pl.wikipedia.org/wiki/Wikipedia:Strona_główna 44937302
https://ja.wikipedia.org/wiki/������������ 41477439
https://en.wikipedia.org/wiki/Special:BlankPage 40173544
https://ru.wikipedia.org/wiki/Служебная:Поиск 35717349
https://zh.wikipedia.org/wiki/Special:最近更改 34860755
https://en.wikipedia.org/wiki/Special:Book 33353391
https://cs.wikipedia.org/wiki/Hlavní_strana 33111756
https://tr.wikipedia.org/wiki/Ana_Sayfa 31452102
https://en.wikipedia.org/wiki/User:GoogleAnalitycsRoman/google-api 30707913
https://es.wikipedia.org/wiki/- 29961995
https://fr.wikipedia.org/wiki/Spécial:Recherche 29103311
https://de.wikipedia.org/wiki/- 28686671
https://sv.wikipedia.org/wiki/Portal:Huvudsida 28455196
https://ja.wikipedia.org/wiki/- 28159010
https://en.wikipedia.org/wiki/Template:GeoTemplate 26438021
https://hu.wikipedia.org/wiki/Kezdőlap 24789961
https://commons.wikimedia.org/wiki/Special:Search 24282981
https://zh.wikipedia.org/wiki/- 24082799
https://ja.wikipedia.org/wiki/特別:検索 22578179
https://ru.wikipedia.org/wiki/Special:Search 22426302
https://ja.wikipedia.org/wiki/��������������� 21354893
https://ja.wikipedia.org/wiki/��������� 21045703
https://fr.wikipedia.org/wiki/Sp?cial:Search 20126196
https://ja.wikipedia.org/wiki/特別:最近の更新 19730989
https://en.wikipedia.org/wiki/Malware 19291150
https://ru.wikipedia.org/wiki/- 18893424
https://nl.wiktionary.org/wiki/Speciaal:Zoeken 18670611
https://ca.wikipedia.org/wiki/Internet 18124959
https://pt.wikipedia.org/wiki/Especial:Pesquisar 17780182
https://de.wikipedia.org/wiki/Spezial:Weblinksuche 17757280
https://en.wikibooks.org/wiki/LaTeX/Document_Structure 17728366
https://ar.wikipedia.org/wiki/الصفحة_الرئيسية 17660205
https://zh.wikipedia.org/wiki/Special:搜索 17136906
https://vi.wikipedia.org/wiki/Trang_Chính 16282348
https://ar.wikipedia.org/wiki/- 15818401
https://da.wikipedia.org/wiki/Forside 15656648
https://de.wikipedia.org/wiki/Special:Search 14939334
https://it.wikipedia.org/wiki/Speciale:Ricerca 14936157
https://id.wikipedia.org/wiki/Halaman_Utama 14921635
https://ja.wikipedia.org/wiki/������������������ 14914357
https://fr.wikipedia.org/wiki/- 14597405
https://ro.wikipedia.org/wiki/Pagina_principală 14508668
https://zh.wikipedia.org/wiki/Special:链出更改 14458353
https://en.wikipedia.org/wiki/Deaths_in_2015 14396192
https://pt.wikipedia.org/wiki/- 13432687
https://en.wikipedia.org/wiki/Special:Watchlist 12814398
https://zh.wikipedia.org/wiki/��������� 12590841
https://de.wikipedia.org/wiki/Spezial:Anmelden 12257873
https://en.wikipedia.org/wiki/Jurassic_World 11950116
https://ru.wikipedia.org/wiki/������ 11216473
https://pl.wikipedia.org/wiki/Specjalna:Szukaj 10965266
https://ru.wikipedia.org/wiki/����� 10913472
https://ja.wikipedia.org/wiki/��������������������� 10779241
https://de.wikipedia.org/wiki/Hauptseite 10330557
https://commons.wikimedia.org/wiki/Main_Page 9996226
https://en.wikipedia.org/wiki/Avengers:_Age_of_Ultron 9844236
https://ru.wikipedia.org/wiki/������� 9489397
https://ru.wikipedia.org/wiki/�������� 9373099
https://en.wiktionary.org/wiki/Wiktionary:Main_Page 9333138
https://nl.wikipedia.org/wiki/Speciaal:Zoeken 9312610
https://en.wikipedia.org/wiki/Pablo_Escobar 9296618
https://ru.wikipedia.org/wiki/���� 9258156
https://ja.wikipedia.org/wiki/������ 9241579
https://ja.wikipedia.org/wiki/������������������������ 9183241
https://en.wikipedia.org/wiki/Donald_Trump 9166835
https://en.wikipedia.org/wiki/List_of_Bollywood_films_of_2015 9134179
https://en.wikipedia.org/wiki/Facebook 9071720
https://kk.wikipedia.org/wiki/Template:AdvancedSiteNotices/ajax 9026941
https://en.wikipedia.org/wiki/Special:MobileMenu 8941355
https://en.wikipedia.org/wiki/Mad_Max:_Fury_Road 8887619
https://uk.wikipedia.org/wiki/Головна_сторінка 8794233
https://en.wikipedia.org/wiki/Game_of_Thrones 8745274
https://fa.wikipedia.org/wiki/ویژه:ورود_به_سامانه 8572793
https://id.wikipedia.org/wiki/- 8507302
https://en.wikipedia.org/wiki/A._P._J._Abdul_Kalam 8284113
https://en.wikipedia.org/wiki/Google 8242968
https://wikimediafoundation.org/wiki/Terms_of_Use 8023245
https://zh.wikipedia.org/wiki/������������ 7998626
https://fr.wikipedia.org/wiki/Wikip��dia:Accueil_principal 7979428
https://ja.wikipedia.org/wiki/��������������������������� 7880728
https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance_spectroscopy 7867169
https://id.wikipedia.org/wiki/Istimewa:Pencarian 7813450
https://sr.wikipedia.org/wiki/Главна_страна 7803138
https://en.wikipedia.org/wiki/United_States 7675129
https://de.wikipedia.org/wiki/Spezial:Buch 7610434
https://en.wikipedia.org/wiki/Eazy-E 7471043
https://en.wikipedia.org/wiki/Ddd 7433941
https://en.wikipedia.org/wiki/Game_of_Thrones_(season_5) 7382274
https://it.wikipedia.org/wiki/- 7346806
https://en.wikipedia.org/wiki/Bajrangi_Bhaijaan 7266442
https://en.wikipedia.org/wiki/Floyd_Mayweather,_Jr. 7262380
https://meta.wikimedia.org/wiki/Main_Page 7257715
https://ru.wikipedia.org/wiki/Служебная:Ссылки_сюда 7170290
https://cs.wikipedia.org/wiki/Speciální:Hledání 7075394
https://ko.wikipedia.org/wiki/위키백과:대문 7004688
https://en.wikipedia.org/wiki/Stephen_Hawking 6979413
https://ar.wikipedia.org/wiki/خاص:بحث 6884847
https://ru.wikipedia.org/wiki/������������������_���������������� 6838779
https://ja.wikipedia.org/wiki/������������������������������ 6811375
https://en.wikipedia.org/wiki/Website 6786692
https://en.wikipedia.org/wiki/Special:CiteThisPage 6740468
https://da.wikipedia.org/wiki/Speciel:Seneste_ændringer 6648351
https://en.wikipedia.org/wiki/2015_in_film 6643983
https://pl.wikipedia.org/wiki/Special:Search 6626950
https://en.wikipedia.org/wiki/Orange_Is_the_New_Black 6593267
https://en.wikipedia.org/wiki/Chris_Kyle 6585441
https://en.wikipedia.org/wiki/Caitlyn_Jenner 6539879
https://ru.wikipedia.org/wiki/���������� 6500017
https://en.wikipedia.org/wiki/Ronda_Rousey 6473199
https://en.wikipedia.org/wiki/Stephen_Curry 6408829
https://es.wikipedia.org/wiki/Especial:Entrar 6395071
https://de.wikipedia.org/wiki/Spezial:Beobachtungsliste 6297673
https://en.wikipedia.org/wiki/India 6224400
https://en.wikipedia.org/wiki/Islamic_State_of_Iraq_and_the_Levant 6208548
https://en.wikipedia.org/wiki/Portal:Current_events 6204018
https://fr.wikipedia.org/wiki/Spécial:Modifications_récentes 6187732
https://ru.wikipedia.org/wiki/��� 6096976
https://no.wikipedia.org/wiki/Portal:Forside 6073743
https://bg.wikipedia.org/wiki/Начална_страница 6068727
https://en.wikipedia.org/wiki/Straight_Outta_Compton_(2015_film) 5971556
https://mediawiki.org/wiki/MediaWiki 5920023
https://en.wikipedia.org/wiki/Bernie_Sanders 5902370
https://en.wikipedia.org/wiki/Baahubali:_The_Beginning 5884765
https://en.wikipedia.org/wiki/Dr._Dre 5881774
https://en.wikipedia.org/wiki/Flags_of_the_Confederate_States_of_America 5866460
https://en.wikipedia.org/wiki/Ruby_Rose 5859660
https://en.wikipedia.org/wiki/N.W.A 5824111
https://en.wikipedia.org/wiki/Terminator_Genisys 5775976
https://he.wikipedia.org/wiki/עמוד_ראשי 5764826
https://en.wikipedia.org/wiki/List_of_Game_of_Thrones_episodes 5738637
https://fr.wikipedia.org/wiki/Accueil_(homonymie) 5687549
https://vi.wikipedia.org/wiki/- 5668948
https://ko.wikipedia.org/wiki/특수:검색 5617110
https://en.wikipedia.org/wiki/List_of_highest-grossing_films 5612829
https://zh.wikipedia.org/wiki/������ 5597419
https://de.wikipedia.org/wiki/Template:GeoTemplate 5536877
https://ru.wikipedia.org/wiki/������������ 5502537
https://en.wikipedia.org/wiki/Ant-Man_(film) 5496621
https://en.wikipedia.org/wiki/Academy_Awards 5476218
https://en.wikipedia.org/wiki/Lionel_Messi 5467386
https://ru.wikipedia.org/wiki/��������� 5405438
https://fa.wikipedia.org/wiki/صفحهٔ_اصلی 5384935
https://en.wikipedia.org/wiki/Ice_Cube 5324917
https://de.wikipedia.org/wiki/Spezial:Letzte_Änderungen 5320086
https://en.wikipedia.org/wiki/Dwayne_Johnson 5301339
https://es.wikipedia.org/wiki/Special:Search 5261454
https://en.wikipedia.org/wiki/World_War_II 5260716
https://en.wikipedia.org/wiki/Suicide_Squad_(film) 5240753
https://pl.wikipedia.org/wiki/Template:GeoTemplate 5208262
https://en.wikipedia.org/wiki/The_Flash_(2014_TV_series) 5114356
https://en.wikipedia.org/wiki/Whitey_Bulger 5110246
https://en.wikipedia.org/wiki/True_Detective_(TV_series) 5066957
https://zh.wikipedia.org/wiki/Running_Man 5060715
https://en.wikipedia.org/wiki/Fear_the_Walking_Dead 5029503
https://en.wikipedia.org/wiki/Taylor_Swift 5002322
https://en.wikipedia.org/wiki/Barack_Obama 4990982
https://en.wikipedia.org/wiki/Cristiano_Ronaldo 4978517
https://en.wikipedia.org/wiki/2015_Copa_América 4975466
https://en.wikipedia.org/wiki/Elizabeth_II 4966913
https://pt.wikipedia.org/wiki/Wikipedia:Página_principal 4920049
https://en.wikipedia.org/wiki/Mr._Robot_(TV_series) 4909087
https://en.wikipedia.org/wiki/Help:IPA_for_English 4907615
https://en.wikipedia.org/wiki/Star_Wars:_The_Force_Awakens 4904135
https://en.wikipedia.org/wiki/The_Walking_Dead_(TV_series) 4889111
https://en.wikipedia.org/wiki/Kanye_West 4861871
https://en.wikipedia.org/wiki/Furious_7 4840048
https://wikimediafoundation.org/wiki/Home 4835328
https://en.wikipedia.org/wiki/Manny_Pacquiao 4820494
https://en.wikipedia.org/wiki/Fetty_Wap 4795556
https://en.wikipedia.org/wiki/Wikipedia 4743801
https://en.wikipedia.org/wiki/Captain_America:_Civil_War 4722014
https://ja.wikipedia.org/wiki/��������������������������������� 4686784
https://en.wikipedia.org/wiki/Paul_Walker 4618488
https://en.wikipedia.org/wiki/Steve_Jobs 4617029
https://en.wikipedia.org/wiki/Suicide_Squad 4599728
https://en.wikipedia.org/wiki/Inside_Out_(2015_film) 4595928
https://en.wikipedia.org/wiki/Kim_Kardashian 4579288
https://es.wikipedia.org/wiki/Especial:Libro 4529801
https://en.wikipedia.org/wiki/Dulce_María 4527902
https://en.wikipedia.org/wiki/Tom_Hardy 4525020
https://en.wikipedia.org/wiki/Serena_Williams 4475772
```
(this list contains some other oddities that are worth investigating, I already looked at Angelsberg and might file a separate bug about it)
```
name=[2], lines=10
hive (wmf)> SELECT project, SUM(view_count) AS views FROM wmf.pageview_hourly WHERE year = 2015 and month = 6 AND page_title LIKE '%�%' GROUP BY project ORDER BY views DESC LIMIT 50;
project views
ru.wikipedia 177741998
ja.wikipedia 107116573
es.wikipedia 44089839
zh.wikipedia 35606734
fr.wikipedia 28696604
en.wikipedia 25515914
de.wikipedia 16948577
pt.wikipedia 15066605
ar.wikipedia 11618348
tr.wikipedia 11529255
pl.wikipedia 10527791
ko.wikipedia 9308818
fa.wikipedia 8156094
uk.wikipedia 6095328
commons.wikimedia 5615428
cs.wikipedia 5473564
he.wikipedia 4971069
th.wikipedia 4887358
hu.wikipedia 4079865
vi.wikipedia 3794512
sv.wikipedia 2975373
it.wikipedia 2835094
sr.wikipedia 2655465
bg.wikipedia 2416994
ru.wiktionary 2308125
el.wikipedia 2234374
ro.wikipedia 2191295
en.wiktionary 1613834
be.wikipedia 1551227
fr.wiktionary 1434420
ca.wikipedia 1259693
sk.wikipedia 1229912
hi.wikipedia 1183813
fi.wikipedia 1042819
nl.wikipedia 1037110
bn.wikipedia 893571
da.wikipedia 874715
kk.wikipedia 809861
no.wikipedia 800887
ka.wikipedia 623034
lt.wikipedia 592751
hr.wikipedia 573796
he.wikisource 497302
hy.wikipedia 456730
ta.wikipedia 431583
mk.wikipedia 430303
fa.wikisource 413805
ko.wikisource 402373
lv.wikipedia 394519
fr.wikisource 391089
```
```
name=[3]
SELECT continent, SUM(view_count) as views FROM wmf.pageview_hourly WHERE year = 2015 AND month = 6 AND page_title = "������������" AND project = "ja.wikipedia" AND agent_type = "user" GROUP BY continent ORDER BY continent LIMIT 1000;
continent views
Africa 2705
Asia 20113970
Europe 112468
North America 449616
Oceania 24136
South America 7862
Unknown 2935
```
```
name=[4]
SELECT user_agent_map['os_family'] AS OS_family, SUM(view_count) as views FROM wmf.pageview_hourly WHERE year = 2015 AND month = 6 AND page_title = "������������" AND project = "ja.wikipedia" AND agent_type = "user" GROUP BY user_agent_map['os_family'] ORDER BY views DESC LIMIT 10;
os_family views
Windows 7 5800663
iOS 5434875
Android 4926276
Windows 8.1 1694772
Other 868088
Mac OS X 633296
Windows Vista 537291
Windows XP 400079
Linux 241776
Windows 8 97222
```
```
name=[5]
hive (default)> SELECT year, month, day, CONCAT(year,"-",LPAD(month,2,"0"),"-",LPAD(day,2,"0")) AS date, SUM(view_count) as views FROM wmf.pageview_hourly WHERE year = 2015 AND page_title LIKE '%�%' AND agent_type = "user" GROUP BY year, month, day ORDER BY year, month, day LIMIT 1000;
```
```
name=[6]
SELECT referer_class, SUM(view_count) as views FROM wmf.pageview_hourly WHERE year = 2015 AND month = 6 AND page_title LIKE '%�%' AND agent_type = "user" GROUP BY referer_class;
referer_class views
external 276431095
internal 124159749
unknown 97135216
```