What is the difference between a "hash join", "merge join" (sort-merge join), and "nested loop join" as physical join strategies?
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Incorrect.
The correct answer is B) They are different algorithms the optimizer may pick to execute the same logical join — nested loop suits small/indexed inputs, hash join builds an in-memory hash table for large unsorted inputs, and merge join exploits pre-sorted inputs
Correct Answer
They are different algorithms the optimizer may pick to execute the same logical join — nested loop suits small/indexed inputs, hash join builds an in-memory hash table for large unsorted inputs, and merge join exploits pre-sorted inputs
These are physical implementation strategies the query optimizer chooses based on data size, sorting, and indexes available: nested loop suits small/indexed cases, hash join handles large unsorted datasets by hashing one side, and merge join is efficient when both inputs are already sorted on the join key.