File processing metrics: in classic data processing, what does the “activity of a file” measure during a processing run?

Introduction / Context:
Traditional batch systems track file “activity” to estimate processing effort and choose suitable organizations (sequential, indexed, hashed). Understanding file activity helps in planning runtimes, optimizing I/O, and deciding when to reorganize or index files for performance.

Given Data / Assumptions:

• “File activity” is a specific metric used in legacy and modern data processing alike.
• We consider updates within a batch or processing cycle.
• The metric influences algorithm and storage choices.

Concept / Approach:
File activity commonly denotes the proportion of existing records that are updated (changed) during a processing run. A high activity level suggests many in-place updates and possibly insertions/deletions, which can degrade efficiency for certain organizations (for example, purely sequential files), prompting the use of indexed access or reorganization strategies. While high activity can reduce efficiency (option b describes an effect), the definition itself is the percentage updated measure (option c).

Step-by-Step Solution:

Verification / Alternative check:
Systems analysis texts define activity in terms of update frequency; engineering estimates of I/O cost often consider this percentage when selecting access methods.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing updates with adds/deletes; or using the consequences of high activity as the definition itself. Keep definition and effects separate for proper analysis.

Final Answer:
is a measure of the percentage of existing records updated during a run