Walled gardens

SQL

SET @ARTICLE_SPACE = 0;

# this finds cycles of 3 articles
select p1.page_title as 'page_1', p2.page_title as 'page_2', p3.page_title as 'page_3'
from page as p1
join page as p2 
  on p2.page_title in (select pl_title from pagelinks where pl_from=p1.page_id and pl_from not in (select pp_page from page_props where pp_propname="disambiguation")) 
  and p1.page_title != p2.page_title
join page as p3 on p3.page_title in (select pl_title from pagelinks where pl_from=p2.page_id and pl_from not in (select pp_page from page_props where pp_propname="disambiguation")) 
  and p2.page_title != p3.page_title
where p1.page_title in (select pl_title from pagelinks where pl_from=p3.page_id and pl_from not in (select pp_page from page_props where pp_propname="disambiguation"))  
  and p3.page_title != p1.page_title
and p1.page_namespace =  @ARTICLE_SPACE and p2.page_namespace =  @ARTICLE_SPACE and p3.page_namespace =  @ARTICLE_SPACE
and p1.page_id < 20 # hack -- testing combinatoric explosion
and not p1.page_is_redirect and not p2.page_is_redirect and not p3.page_is_redirect

limit 1000;
SQL

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