Question

What is the best database model to store user visits and count unique users using the IP in a big database with 1.000.000 rows for example?

SELECT COUNT(DISTINCT ip) FROM visits

But with 1.000.000 diferent ip’s it can be a slow query. Caching will not return the real number.

How big stats systems counts uniques visits?

Answer 1

Have another MyISAM table with only IP column and UNIQUE index on it. You’ll get the proper count in no time (MyISAM caches number of rows in table)

[added after comments]

If you also need to count visits from each IP, add one more column visitCount and use

INSERT INTO 
  visitCounter (IP,visitCount) 
VALUES 
  (INET_ATON($ip),1) 
ON DUPLICATE KEY UPDATE 
  SET visitCount = visitCount+1