During a structured database redesign process, how many parallel copies (environments) of the schema are typically maintained to separate development, testing, and production concerns?

Introduction / Context:
Professional database change workflows separate concerns across environments. Isolating work-in-progress from validation and from live operations reduces risk, clarifies responsibilities, and enables controlled deployments. The question asks how many distinct schema copies are typically used in practice.

Given Data / Assumptions:

• Teams follow a change management lifecycle.
• Production data must remain stable and available.
• Testing must happen before release to production.

Concept / Approach:

A common pattern is to maintain three environments: development (or sandbox) for rapid iteration, test (or QA/staging) for validation under realistic data and workload, and production for live users. Each environment has its own schema copy so that DDL/DML can be rehearsed and verified without jeopardizing production.

Step-by-Step Solution:

Verification / Alternative check:

Audit trails and release notes should show each change advancing from Dev → Test → Prod with sign-offs, demonstrating three separate schema copies during the process.

Why Other Options Are Wrong:

One: mixes development with production, high risk.

Two: lacks a dedicated test stage or a safe development area.

Four: possible in larger orgs (e.g., perf, UAT), but “typical” is three.

Common Pitfalls:

Testing only on developers’ machines, skipping staging, or allowing schema drift between environments due to manual, unscripted changes.

Final Answer:

Three