Cost Models
Throughout this course, we compare costs of DB operations
Important aspects in determining cost:
- data is always transferred to/from disk as whole blocks (pages)
- cost of manipulating tuples in memory is negligible
- overall cost determined primarily by #data-blocks read/written
Complicating factors in determining costs:
- not all page accesses require disk access (buffer pool)
- tuples typically have variable size (tuples/page ?)
More details later ...
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