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DBMS Nested-Loop Join Algorithm MCQs

DBMS Nested-Loop Join Algorithm MCQs: This section contains multiple-choice questions and answers on Nested-Loop Join Algorithm in DBMS.
Submitted by Anushree Goswami, on May 15, 2022

1. Nested loop joins are joins in which there are two nested ___ loops.

1. Of
2. For
3. Nor
4. Xor

Answer: B) For

Explanation:

Nested loop joins are joins in which there are two nested for loops.

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2. An algorithm known as the ___ is used to perform the nested loop join, e.g. θ on two relations r and s.

1. Loop Join Algorithm
2. Nested Loop Join Algorithm
3. Join Algorithm
4. None of the above

Answer: B) Nested Loop Join Algorithm

Explanation:

An algorithm known as the Nested loop join algorithm is used to perform the nested loop join, e.g. θ on two relations r and s.

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3. Computations are carried out by r ⋈ θ s where r represents the ___ relation and s represents the ___ relation.

1. Outer, Inner
2. Inner, Outer
3. Inner
4. Outer

Answer: A) Outer, Inner

Explanation:

Computations are carried out by r ⋈ _θ s where r represents the outer relation and s represents the inner relation.

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4. Unlike linear file scans, nested-loop joins don't require any ____ to access the data.

1. Setting
2. Indexing
3. Pointing
4. None

Answer: B) Indexing

Explanation:

Unlike linear file scans, nested-loop joins don't require any indexing to access the data.

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5. Nesting-loop joins are very ____ due to the fact that each pair of tuples in the two given relations must be computed and examined separately.

1. Cheap
2. Expensive
3. Few
4. None

Answer: B) Expensive

Explanation:

Nesting-loop joins are very expensive due to the fact that each pair of tuples in the two given relations must be computed and examined separately.

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6. In the event that any of the relationships given is completely compatible with the memory, it is essential to use that relationship as the ___ relation.

1. Inner
2. Outer
3. Both a and b
4. None of the above

Answer: A) Inner

Explanation:

In the event that any of the relationships given is completely compatible with the memory, it is essential to use that relationship as the inner relation.

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7. A nested-loop join with blocks of the inner relation paired with blocks of the outer relation is known as a ____ nested-loop join.

1. Inner
2. Outer
3. Block
4. Nested

Answer: C) Block

Explanation:

A nested-loop join with blocks of the inner relation paired with blocks of the outer relation is known as a block nested-loop join.

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8. In a situation where the buffer size is small enough to store the entire relationship in memory, the ____ nested-loop join saves the need for major ____ accesses.

1. Block
2. Inner
3. Outer
4. None

Answer: A) Block

Explanation:

In a situation where the buffer size is small enough to store the entire relationship in memory, the block nested-loop join saves the need for major block accesses.

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9. Every tuple from one block is paired with every tuple from the other block in the ___ to produce all pairs of tuples.

1. Block nested-loop
2. Nested-loop
3. Join-loop
4. None

Answer: A) Block nested-loop

Explanation:

Every tuple from one block is paired with every tuple from the other block in the block nested-loop to produce all pairs of tuples.

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10. Block Nested-Loop ___ algorithm is the algorithm used to perform nested-loop block joins.

1. Join
2. Block
3. Inner
4. Outer

Answer: B) Block

Explanation:

Block Nested-Loop Join algorithm is the algorithm used to perform nested-loop block joins.

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11. A block nested-loop join is worst case when blocks in the inner relation s are read ____ for each block in the outer relation r.

1. Once
2. Twice
3. Thrice
4. Multiple times

Answer: A) Once

Explanation:

A block nested-loop join is worst case when blocks in the inner relation s are read once for each block in the outer relation r.

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12. For each tuple in the inner relationship s, the ____-loop join reads it once for each tuple in the outer relationship r.

1. Join
2. Nested
3. Block
4. None

Answer: B) Nested

Explanation:

For each tuple in the inner relationship s, the nested-loop join reads it once for each tuple in the outer relationship r.

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13. It is efficient to use the inner relation s as the outer relation if neither of the given relations r or s completely fit into the ____.

1. Block
2. Size
3. Memory
4. Storage

Answer: C) Memory

Explanation:

It is efficient to use the inner relation s as the outer relation if neither of the given relations r or s completely fit into the memory.

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14. As soon as the first match is found for each outer relation tuple in a/an _____, the inner loop terminates.

1. Equijoin
2. Natural join
3. Both A and B
4. None of the above

Answer: C) Both A and B

Explanation:

As soon as the first match is found for each outer relation tuple in an equijoin or natural join, the inner loop terminates.

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15. Rather than relying on disk blocks for the block nested-loop join algorithm, we can use the ____ size that will fit into memory while allowing enough room for buffers of the inner relations.

1. Smallest
2. Tiny
3. Largest
4. None

Answer: C) Largest

Explanation:

Rather than relying on disk blocks for the block nested-loop join algorithm, we can use the largest size that will fit into memory while allowing enough room for buffers of the inner relations.

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16. A scanning of the inner loop can be performed alternately in _____ directions.

1. Forward
2. Reverse
3. Both A and B
4. None of the above

Answer: C) Both A and B

Explanation:

A scanning of the inner loop can be performed alternately in forward and reverse directions.

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17. Additionally, the order of the request allows for ____ of the data left over from the previous scan.

1. Misuse
2. Use
3. Reuse
4. None

Answer: C) Reuse

Explanation:

Additionally, the order of the request allows for reuse of the data left over from the previous scan.

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18. We can replace the file scans with highly efficient index lookups if an index is present on the ___ attribute of the inner loop.

1. Log
2. Join
3. Array
4. Stack

Answer: B) Join

Explanation:

We can replace the file scans with highly efficient index lookups if an index is present on the join attribute of the inner loop.

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19. A nested-loop indexed join can be performed using ____ created during the evaluation of the join.

1. Existing indexes
2. Temporary indexes
3. Both A and B
4. None of the above

Answer: C) Both A and B

Explanation:

A nested-loop indexed join can be performed using either existing indexes or temporary indexes created during the evaluation of the join.

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20. Nested-loop joins optimized with indexed nested loops are ____ than traditional loop joins.

1. Slower
2. Faster
3. Comparatively Slower
4. None

Answer: B) Faster

Explanation:

Nested-loop joins optimized with indexed nested loops are faster than traditional loop joins.

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