fixes #9524 Query generated by Live plugin is too heavy

plugins/Live/API.php

@@ -260,10 +260,19 @@ class API extends \Piwik\Plugin\API
     {
         Piwik::checkUserHasViewAccess($idSite);
 
+        // for faster performance search for a visitor within the last 7 days first
+        $minTimestamp = Date::now()->subDay(7)->getTimestamp();
         $dataTable = $this->loadLastVisitorDetailsFromDatabase(
-            $idSite, $period = false, $date = false, $segment, $offset = 0, $limit = 1
+            $idSite, $period = false, $date = false, $segment, $offset = 0, $limit = 1, $minTimestamp
         );
 
+        if (0 >= $dataTable->getRowsCount()) {
+            // no visitor found in last 7 days, look further back. This query might be quite slow
+            $dataTable = $this->loadLastVisitorDetailsFromDatabase(
+                $idSite, $period = false, $date = false, $segment, $offset = 0, $limit = 1
+            );
+        }
+
         if (0 >= $dataTable->getRowsCount()) {
             return false;
         }