Consider a join between relations $r(R)$ and $s(S)$ using the nested-loop method. There are 3 buffers, each of size equal to a disk block, out of which one buffer is reserved for intermediate results. Assuming $|r(R)|

Question

Consider a join between relations $r(R)$ and $s(S)$ using the nested-loop method. There are 3 buffers, each of size equal to a disk block, out of which one buffer is reserved for intermediate results. Assuming $|r(R)| < |s(S)|$, the join will have fewer disk block accesses if

Accepted Answer

join selection factor between $r(R)$ and $s(S)$ is less than 0.5.. In nested-loop join with limited buffers, placing the smaller relation in the outer loop generally reduces repeated scans of the larger relation. The selection factor also affects the amount of intermediate output; when it is small, fewer result tuples are produced and fewer block accesses are needed overall. Hence the stated condition is the correct one.

Consider a join between relations $r(R)$ and $s(S)$ using the nested-loop method. There are 3 buffers, each of size equal to a disk block, out of which one buffer is reserved for intermediate results. Assuming $|r(R)| < |s(S)|$, the join will have fewer disk block accesses if

Solution

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