Question at position 7 (Comprehensive) In the context of B-Trees, what is a disk block?A security mechanism that prevents unauthorized access to B-Tree data on disk.A fixed-size unit of data transfer between the disk and the memory.A cache that stores recently accessed B-Tree keys for faster lookup.A section of memory used to temporarily store B-Tree nodes during computation.Clear my selection题目解析

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Question at position 7 (Comprehensive) In the context of B-Trees, what is a disk block?A security mechanism that prevents unauthorized access to B-Tree data on disk.A fixed-size unit of data transfer between the disk and the memory.A cache that stores recently accessed B-Tree keys for faster lookup.A section of memory used to temporarily store B-Tree nodes during computation.Clear my selection题目解析

BlackTom AI · Accepted Answer

Question: In the context of B-Trees, what is a disk block?

Option 1: A security mechanism that prevents unauthorized access to B-Tree data on disk.
This choice describes a security feature such as encryption or access control, not a fundamental unit used for storage or transfer of data between disk and memory. B-trees operate on data structures stored on disk, but a disk block is not inherently a security mechanism.

Option 2: A fixed-size unit of data transfer between the disk and the memory.
This option aligns with the standard definition of a disk block: a contiguous chunk of storage with a fixed size that is read from or written to by the operating system and hardware during I/O operations. B-trees store their nodes on disk in these blocks, and algorithms fetch a block to access or modify a node.

Option 3: A cache that stores recently accessed B-Tree keys for faster lookup.
Cache refers to a separate fast-access storage layer that speeds up repeated data retrieval, but it’s typically in memory or on a separate caching device. A disk block is not a cache; it’s a physical storage unit, whereas caching is an optimization strategy.

Option 4: A section of memory used to temporarily store B-Tree nodes during computation.
This describes in-memory buffering or workspace used during processing, not the on-disk storage unit. Disk blocks persist on disk and are not merely temporary memory allocations during computation.

Key takeaway: The term disk block denotes the fixed-size chunk used for I/O between disk and RAM, which underpins how data structures like B-trees are laid out and accessed on storage devices. The other options reflect related concepts (security, caching, temporary memory) but do not define the disk block itself.

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