Consider the schema below.

Student$($sid$,$ name, login$,$ age, gpa$)$

Borrow$($sid$,$isbn, duration$)$

Textbook $($isbn$,$ name$)$

Assume a data block has a size of $1024$ bytes. No tuple is allowed to span two blocks.

There are $5000$ tuples in table Student. Each tuple takes $100$ bytes to store.

There are $10000$ textbook tuples in the table Textbook. Each tuple also takes $100$ bytes.

There are $30000$ borrowing records stored in Borrow. Each tuple takes $150$ bytes.

For each of the following queries, estimate the number of blocks to be retrieved $($in the worst case$)$

under specified conditions.

$($a$)$ There is no index available;

query: ${}_{\text{a}\text{g}\text{e}}=18($Student$)$

$($b$)$ Use a B$+$ tree index on attribute Student.sid with height $4$;

query: Student$)$

$($c$)$ Use block nested loop join, and main memory only holds one block per relation.

query: Student $|><mi\; id="EditorElement\_4698715">|</mi>$ Borrow

$($d$)$ Use nested loop join and the smaller relation fits entirely in the memory;

selection is done $"$on the fly" in memory.

query: ${}_{\text{d}\text{u}\text{r}\text{a}\text{t}\text{i}\text{o}\text{n}}<mn\; id="EditorElement\_4698537">1</mn><mn\; id="EditorElement\_4698538">0</mn><mn\; id="EditorElement\_4698539">0</mn><mtext\; id="EditorElement\_4698498"></mtext><mi\; id="EditorElement\_4698499">(</mi>$Borrow $|><mi\; id="EditorElement\_4698489">|</mi>$ Textbook$)$