Nested-Loops
Costs to Consider
•We can reach 30,000 rows or more per second with nested loops to cached data, a trivial time compared to the magnitude of the output, unless a bad join order reaches tables in the wrong order! (What application must produce multiple 30,000-plus-row reports per minute, even in the worst case?)
•Where nested-loops costs matter, it is because physical I/O
time is high, or the join order is wrong.