Impact of Buffering
If several operations are executing concurrently, estimating the number of available buffer pages is guesswork.
Repeated access patterns interact with buffer replacement policy.
- e.g., Inner relation is scanned repeatedly in Simple Nested Loop Join. With enough buffer pages to hold inner, replacement policy does not matter. Otherwise, MRU is best, LRU is worst (sequential flooding).
- Does replacement policy matter for Block Nested Loops?
- What about Index Nested Loops? Sort-Merge Join?