Find entries of 20 or more by contact within one minute of each entry

Question

We are collecting some analytics data for contacts & each page they visit. A lot of the analytics data is from malicious attacks or bots, so they are hitting like 20+ pages

Answer 1

You can get contacts that visited 20 pages within a minute using lag():

select distinct contactid
from (select t.*,
             lag(datecreated, 19) over (partition by contactid order by datecreated) as lag20
      from t
     ) t
where lag20 > dateadd(minute, -1, datecreated);

That is, there are 20 rows within a minute if you look back 19 rows and that row is less than a minute before the current row.