Semester 6 Checkpoint Gate

Required Output Classification

Required output	Classification	Public/private guidance
Closed-book prompts, self-assessment answers, and skills matrices	Practice artifact	Use for honest calibration; do not publish raw answers unless rewritten as a study guide.
Required evidence gate items, sign-off checklist, and readiness decision	Checkpoint evidence	Keep as private progression evidence; share only sanitized summaries with mentors or reviewers.
Repair artifacts produced after a weak checkpoint, such as corrected solutions, diagrams, traces, benchmarks, or runbooks	Checkpoint evidence	Store beside the checkpoint so the remediation trail is inspectable without making mistakes public.
Reviewer notes or mentor feedback that materially improve a project artifact	Portfolio candidate	Convert into public-safe acknowledgements or changelog entries only after removing private feedback context.

Pass this gate before you call Semester 6 complete. The standard is not exposure. The standard is whether you can produce correct artifacts and defend your tradeoffs.

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What You Must Be Able To Do

Area	Required capability	Evidence you should have
Module 1: Relational Databases & SQL	Design a clean schema, justify keys and constraints, and write non-trivial queries correctly	Schema draft, representative SQL queries, and short notes explaining design choices
Module 2: Storage Engines & Indexing	Explain how the engine stores and retrieves data, and choose indexes based on workload	Query-plan notes, index rationale, and one workload comparison
Module 3: Replication & Partitioning	Describe read/write paths, lag, failover, sharding pressure, and user-visible failure modes	Replication sketch, partitioning tradeoff notes, and a short failure analysis
Module 4: Transactions & Consistency	Identify anomalies, compare isolation choices, and explain what correctness guarantee is actually needed	Transaction timeline examples and consistency decision notes
Module 5: Distributed Systems Fundamentals	Reason about time, partial failure, quorum intuition, and coordination cost	Distributed scenario writeup with tradeoffs and failure assumptions stated clearly

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Closed-Book Readiness Prompts

Answer these without notes first. If you cannot answer one clearly, that is the next review target.

1. Why is a bad schema problem not fixed by adding indexes later?
2. What changes operationally when a workload moves from read-heavy to write-heavy?
3. How can replication lag create a user-visible correctness problem even if the database is technically healthy?
4. What anomaly does a transaction isolation level prevent, and what does it still allow?
5. Why is distributed consensus expensive, and when is that cost justified?

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Skills Verification Matrix

Skill	Can do without notes?	Evidence path or artifact	If not yet, remediation
Write joins, aggregates, subqueries, and filters that match the business question			Rework Module 1 exercises and explain each query aloud
Interpret why one index helps one query and harms another workload			Revisit Module 2 storage/index notes and compare plans
Explain leader-follower reads, lag, and failover behavior			Redraw Module 3 replication paths from memory
Compare two isolation choices for the same workflow			Rebuild Module 4 anomaly examples and recovery notes
Analyze a partial-failure distributed scenario without slogans			Review Module 5 time/failure concepts and rewrite one scenario cleanly
Define tests that protect a schema or transaction invariant			Add database-focused tests to project work
Describe data-security controls for credentials and sensitive fields			Review access control and secret-handling notes
Name the runtime signals that would tell you the data plane is degrading			Add observability notes to the project or module labs

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Required Artifacts Before Advancing

• one schema with constraints and justification
• one query set with correctness evidence
• one storage/index tradeoff writeup
• one replication or partitioning scenario analysis
• one transaction or consistency analysis
• one distributed failure scenario analysis
• one repo or notebook showing steady, reviewable work rather than a last-minute dump

Blockers

Do not move on if any of these are true:

• you can write SQL only by trial and error
• you cannot explain why an index helps in one case and hurts in another
• you talk about consistency, CAP, or consensus only in buzzwords
• you do not have concrete evidence for schema, transaction, or distributed tradeoff decisions

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Sign-Off

• Date completed:
• Honest self-rating (1-5):
• Most important weakness still open:
• Concrete fix scheduled before Semester 7:

Added Gate Evidence

The checkpoint reviewer should see:

• schema evidence: ER diagram, DDL, constraints, and normalization worksheet
• SQL evidence: query file plus result or plan evidence
• model-decision evidence: a short note comparing relational and document approaches for the same workflow
• operational evidence: one index decision, one migration risk, and one rollback note

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Mastery Rubric

Level	Evidence
Beginner pass	Can answer direct questions and complete familiar exercises with light notes.
Solid pass	Can solve new variants, explain choices, and connect the work to Semester 5 Operating Systems and Networking.
Strong pass	Can defend tradeoffs, identify failure modes, and produce clean evidence in the portfolio artifact.
Not ready	Relies on copied solutions, cannot explain mistakes, or lacks durable artifacts.

Retake and Repair Rule

If a section is weak, do not only reread. Repair it by producing new evidence: a corrected solution, a fresh implementation, a rewritten proof, a benchmark, a diagram, a runbook, or a short teaching note.

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Answer-Quality Examples

Use these examples when grading written answers or spoken explanations.

Quality	Example pattern
Weak	Names a concept but gives no example, constraint, or failure case.
Acceptable	Defines the concept and applies it to a familiar exercise.
Strong	Applies the concept to a new variant and explains why an alternative would fail.
Portfolio-ready	Connects the concept to Semester 5 Operating Systems and Networking, current project evidence, and a future capstone decision.

Interleaving Prompt

For any missed answer, add one sentence starting with: This depends on an earlier skill because...

Calibration Materials

Use these learner-visible calibration materials before self-grading or requesting review:

• Answer key and solution outlines
• Rubric, passing standard, strong traits, and weak patterns