Thanks vipsoft for the help !

I have fixed the data in piwik_log_visit and piwik_log_action, as illustrated by the requests below.

I have also dropped all the piwik_archive_* tables, but unfortunately, my graphs are still showing twice the visits as expected.

Any idea ? Is there a cache somewhere, or are my queries not representative of what piwik is doing internally to prepare the graph data ?

BEFORE:

```
mysql> SELECT count(distinct visitor_idcookie) as nb_uniq_visitors,count(*) as nb_visits,sum(visit_total_actions) as nb_actions,max(visit_total_actions) as max_actions,sum(visit_total_time) as sum_visit_length,sum(case visit_total_actions when 1 then 1 else 0 end) as bounce_count,sum(case visit_goal_converted when 1 then 1 else 0 end) as nb_visits_converted FROM piwik_log_visit where visit_last_action_time >= "2011-01-15" and visit_last_action_time < "2011-01-16";
+------------------+-----------+------------+-------------+------------------+--------------+---------------------+
| nb_uniq_visitors | nb_visits | nb_actions | max_actions | sum_visit_length | bounce_count | nb_visits_converted |
+------------------+-----------+------------+-------------+------------------+--------------+---------------------+
| 233 | 1277 | 1973 | 59 | 48702 | 1173 | 0 |
+------------------+-----------+------------+-------------+------------------+--------------+---------------------+
1 row in set (0.08 sec)
```

AFTER:

```
mysql> SELECT count(distinct visitor_idcookie) as nb_uniq_visitors,count(*) as nb_visits,sum(visit_total_actions) as nb_actions,max(visit_total_actions) as max_actions,sum(visit_total_time) as sum_visit_length,sum(case visit_total_actions when 1 then 1 else 0 end) as bounce_count,sum(case visit_goal_converted when 1 then 1 else 0 end) as nb_visits_converted FROM piwik_log_visit where visit_last_action_time >= "2011-01-15" and visit_last_action_time < "2011-01-16";
+------------------+-----------+------------+-------------+------------------+--------------+---------------------+
| nb_uniq_visitors | nb_visits | nb_actions | max_actions | sum_visit_length | bounce_count | nb_visits_converted |
+------------------+-----------+------------+-------------+------------------+--------------+---------------------+
| 233 | 655 | 1973 | 59 | 48702 | 552 | 0 |
+------------------+-----------+------------+-------------+------------------+--------------+---------------------+
1 row in set (0.07 sec)
```