diff --git a/pkg/aggregator/store.go b/pkg/aggregator/store.go
index 80903f6..a01076c 100644
--- a/pkg/aggregator/store.go
+++ b/pkg/aggregator/store.go
@@ -10,7 +10,6 @@ import (
 )
 
 func (agg *Aggregator) getSiteStats(r *results, siteID int64, t time.Time) (*models.SiteStats, error) {
-	// get from map
 	cacheKey := fmt.Sprintf("%d-%s", siteID, t.Format("2006-01-02"))
 	if stats, ok := r.Sites[cacheKey]; ok {
 		return stats, nil
diff --git a/pkg/datastore/sqlstore/migrations/mysql/10_alter_stats_table_constraints.sql b/pkg/datastore/sqlstore/migrations/mysql/10_alter_stats_table_constraints.sql
new file mode 100644
index 0000000..05d1617
--- /dev/null
+++ b/pkg/datastore/sqlstore/migrations/mysql/10_alter_stats_table_constraints.sql
@@ -0,0 +1,19 @@
+-- +migrate Up
+
+DROP INDEX IF EXISTS unique_daily_site_stats;
+DROP INDEX IF EXISTS unique_daily_page_stats;
+DROP INDEX IF EXISTS unique_daily_referrer_stats;
+
+CREATE UNIQUE INDEX unique_daily_site_stats ON daily_site_stats(site_id, date);
+CREATE UNIQUE INDEX unique_daily_page_stats ON daily_page_stats(site_id, hostname, pathname, date);
+CREATE UNIQUE INDEX unique_daily_referrer_stats ON daily_referrer_stats(site_id, hostname, pathname, date);
+
+-- +migrate Down
+
+DROP INDEX IF EXISTS unique_daily_site_stats;
+DROP INDEX IF EXISTS unique_daily_page_stats;
+DROP INDEX IF EXISTS unique_daily_referrer_stats;
+
+CREATE UNIQUE INDEX unique_daily_site_stats ON daily_site_stats(date);
+CREATE UNIQUE INDEX unique_daily_page_stats ON daily_page_stats(hostname, pathname, date);
+CREATE UNIQUE INDEX unique_daily_referrer_stats ON daily_referrer_stats(hostname, pathname, date);
\ No newline at end of file
diff --git a/pkg/datastore/sqlstore/migrations/postgres/11_alter_stats_table_constraints.sql b/pkg/datastore/sqlstore/migrations/postgres/11_alter_stats_table_constraints.sql
new file mode 100644
index 0000000..05d1617
--- /dev/null
+++ b/pkg/datastore/sqlstore/migrations/postgres/11_alter_stats_table_constraints.sql
@@ -0,0 +1,19 @@
+-- +migrate Up
+
+DROP INDEX IF EXISTS unique_daily_site_stats;
+DROP INDEX IF EXISTS unique_daily_page_stats;
+DROP INDEX IF EXISTS unique_daily_referrer_stats;
+
+CREATE UNIQUE INDEX unique_daily_site_stats ON daily_site_stats(site_id, date);
+CREATE UNIQUE INDEX unique_daily_page_stats ON daily_page_stats(site_id, hostname, pathname, date);
+CREATE UNIQUE INDEX unique_daily_referrer_stats ON daily_referrer_stats(site_id, hostname, pathname, date);
+
+-- +migrate Down
+
+DROP INDEX IF EXISTS unique_daily_site_stats;
+DROP INDEX IF EXISTS unique_daily_page_stats;
+DROP INDEX IF EXISTS unique_daily_referrer_stats;
+
+CREATE UNIQUE INDEX unique_daily_site_stats ON daily_site_stats(date);
+CREATE UNIQUE INDEX unique_daily_page_stats ON daily_page_stats(hostname, pathname, date);
+CREATE UNIQUE INDEX unique_daily_referrer_stats ON daily_referrer_stats(hostname, pathname, date);
\ No newline at end of file
diff --git a/pkg/datastore/sqlstore/migrations/sqlite3/10_alter_stats_table_constraints.sql b/pkg/datastore/sqlstore/migrations/sqlite3/10_alter_stats_table_constraints.sql
new file mode 100644
index 0000000..05d1617
--- /dev/null
+++ b/pkg/datastore/sqlstore/migrations/sqlite3/10_alter_stats_table_constraints.sql
@@ -0,0 +1,19 @@
+-- +migrate Up
+
+DROP INDEX IF EXISTS unique_daily_site_stats;
+DROP INDEX IF EXISTS unique_daily_page_stats;
+DROP INDEX IF EXISTS unique_daily_referrer_stats;
+
+CREATE UNIQUE INDEX unique_daily_site_stats ON daily_site_stats(site_id, date);
+CREATE UNIQUE INDEX unique_daily_page_stats ON daily_page_stats(site_id, hostname, pathname, date);
+CREATE UNIQUE INDEX unique_daily_referrer_stats ON daily_referrer_stats(site_id, hostname, pathname, date);
+
+-- +migrate Down
+
+DROP INDEX IF EXISTS unique_daily_site_stats;
+DROP INDEX IF EXISTS unique_daily_page_stats;
+DROP INDEX IF EXISTS unique_daily_referrer_stats;
+
+CREATE UNIQUE INDEX unique_daily_site_stats ON daily_site_stats(date);
+CREATE UNIQUE INDEX unique_daily_page_stats ON daily_page_stats(hostname, pathname, date);
+CREATE UNIQUE INDEX unique_daily_referrer_stats ON daily_referrer_stats(hostname, pathname, date);
\ No newline at end of file