The most common source of change data in refreshing a data warehouse is _______.

From DeepSeek:

The correct answer is:

C. Logged change data

Explanation:
In data warehouse refreshes, logged change data is the most common and efficient source for identifying changes in source systems. Here’s why:

Logged Change Data:

Captured through database transaction logs (e.g., Oracle Redo Logs, SQL Server CDC).

Tracks inserts, updates, and deletes in real-time or near-real-time.

Minimizes overhead on source systems compared to full snapshots.

Why Not Other Options?

A. Queryable change data: Requires querying source systems directly (inefficient for large-scale changes).

B. Cooperative change data: Rare; implies source systems are explicitly designed to cooperate (uncommon in practice).

D. Snapshot change data: Compares full snapshots (high resource usage, slower for large datasets).

Advantages of Logged Change Data:

Low latency: Enables near-real-time updates.

Minimal impact: Does not require querying source tables directly.

Accuracy: Prevents missing intermediate changes.