Sequential file organization and primary key scans: When data are stored sequentially by the primary key, how fast is sequential retrieval across that key order typically considered?

Introduction / Context:
File organization affects access speed. With sequential storage ordered by the primary key, reading records in key order exploits physical locality and minimal repositioning, which is ideal for range scans and reporting.

Given Data / Assumptions:

• Records are stored physically in primary-key order.
• Access pattern is a forward scan by key (sequential retrieval).
• Underlying storage favors streaming reads.

Concept / Approach:

Sequential access minimizes random I/O and leverages read-ahead. Whether in classic sequential files or clustered indexes in databases, a full or range scan in key order is typically very fast compared with scattered random lookups.

Step-by-Step Solution:

Verification / Alternative check:

Benchmark a range scan versus random key lookups; sequential throughput is markedly higher, especially on spinning media and still favorable on SSDs due to cache coherence.

Why Other Options Are Wrong:

Moderately fast/Slow/Impractical: contradict established I/O behavior for ordered sequential scans.

Common Pitfalls:

Assuming random access equals sequential speed; mixing wide rows and excessive page splits can still degrade performance if maintenance is neglected.

Final Answer:

Very fast