when viewing 'values' as plain text, there are some unneeded queries :

SELECT i.itemid, i.value_type FROM items i WHERE (i.itemid IN (18468))
SELECT MAX(i.history) as history, MAX(i.trends) as trends FROM items i WHERE (i.itemid IN (18468))
SELECT ht.itemid, MIN(ht.clock) as min_clock FROM trends ht WHERE (ht.itemid IN (18468)) GROUP BY ht.itemid