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with t as (select tagname,count(*) posts from posts p join users u on p.owneruserid=u.id join posttags pt on pt.postid=p.id join tags on tags.id=pt.tagid where lower(u.location) like '%russia%' and year(p.creationdate)=2017 group by tagname) select * from t where t.posts=(select max(posts) from t)