Materialized views / snapshots: Does the refresh cost depend on whether the snapshot is simple or complex?

Introduction / Context:
In many DBMSs, “snapshots” or materialized views can be refreshed incrementally or fully, and their definition influences refresh cost.

Given Data / Assumptions:

• Simple views (single-table or certain join/aggregation patterns) can track changes efficiently.
• Complex views (arbitrary joins, non-deterministic functions) may not qualify for incremental refresh.
• Systems may require logs or MV logs to support fast refresh.

Concept / Approach:
Fast (incremental) refresh uses change data to update only affected rows, reducing cost. Complex definitions may force complete refresh, reading base tables and recomputing results, which is more expensive.

Step-by-Step Solution:
Classify the snapshot as simple or complex based on DBMS rules.Check availability of change tracking (logs).Choose fast or complete refresh accordingly.Estimate cost: incremental is typically cheaper than full recompute.

Verification / Alternative check:
DBMS documentation lists allowable constructs for fast refresh and their performance implications.

Why Other Options Are Wrong:
Replication mode, OLTP/OLAP labels, or index type do not dictate refresh complexity alone.

Common Pitfalls:
Assuming all materialized views can fast-refresh; overlooking required logging or constraints.

Final Answer:
Applies — simple snapshots may fast-refresh; complex often require more work