Можно ли улучшить производительность, взяв следующий SQL:
SELECT t1.id,
t1.name,
t2.subname,
t2.refvalue
FROM table1 AS t1
CROSS apply (SELECT TOP 1 t2.subid,
t2.subname,
t3.refvalue
FROM table2 AS t2
INNER JOIN table3 AS t3
ON t2.subid = t3.subid
ORDER BY lastupdated DESC) AS t2
И переписать его так, чтобы он выглядел так:
SELECT t1.id,
t1.name,
t2.subname,
t3.refvalue
FROM table1 AS t1
CROSS apply (SELECT TOP 1 t2.subid,
t2.subname
FROM table2 AS t2
ORDER BY lastupdated DESC) AS t2
INNER JOIN table3 AS t3
ON t2.subid = t3.subid