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Relational Modelling

Normalisation, keys, constraints and the invariants a schema enforces.

3Questions
10Flashcards
4Terms
1Deliverables
Drill this topic All of Data Architecture
Questions

3 to work through

  1. intermediate

    A team proposes storing the customer's address on every order row "so order history is accurate". Is that denormalisation or a modelling error?

    2 min answer
  2. intermediate

    A team wants to store a product's variable attributes as a JSON column rather than modelling them as tables. When is that right and what is given up?

    2 min answer
  3. advanced Multiple choice

    An issue-tracking product lets every customer define custom fields, workflows and screens. Which data model should the platform use for custom fields?

    2 min answer
Terminology

4 terms in this topic

concept

Foreign Key Constraint

A database-enforced rule that a referencing value must exist in the referenced table — referential integrity that no application bug can violate.

 practice

Normalisation

Organising a schema so each fact is stored exactly once, removing the update anomalies that duplication creates.

 practice

Relational Modelling

Designing a schema around entities, relationships and enforced constraints — still the correct default for most transactional systems.

 concept

Surrogate Key

A system-generated identifier with no business meaning, used as the primary key instead of a naturally occurring business value.
Deliverables

1 artifact you would hand over

Data View

Entity Relationship Diagram

Entities, their attributes and the cardinality between them — where the notation on the end of each line is the actual content.
Data Architecture

Neighbouring topics

Data Architecture

General material on structuring, storing and governing data.

10 quiz 31 cards 25 terms

NoSQL Stores

Key-value, document, wide-column and graph — what each buys and forbids.

5 quiz 13 cards 4 terms

Indexing

Designing indexes per query shape, and paying for them on every write.

5 quiz 12 cards 6 terms

Query Optimisation

Reading a plan, fixing statistics, and finding the real bottleneck.

3 quiz 11 cards 4 terms

Transactions & Isolation

ACID, isolation levels, and the anomalies each level permits.

3 quiz 10 cards 4 terms

Replication

Primaries, replicas, lag, and synchronous versus asynchronous durability.

4 quiz 14 cards 6 terms

Partitioning & Sharding

Splitting data across machines, and the one-way door of a partition key.

6 quiz 12 cards 10 terms

Caching Strategies

Cache-aside, read-through, write-through and where each belongs.

7 quiz 15 cards 6 terms

Cache Invalidation

Stampedes, penetration, staleness windows and versioned keys.

3 quiz 7 cards 2 terms

CQRS

Separating the write model from the read models that serve queries.

4 quiz 10 cards 5 terms

Event Sourcing

Storing the change log as the system of record, and what that costs forever.

5 quiz 13 cards 4 terms

Change Data Capture

Turning a database's replication log into a stream, and its coupling risk.

5 quiz 14 cards 5 terms

Data Warehousing

Dimensional modelling, star schemas and analytical workloads.

4 quiz 13 cards 3 terms

Data Lakes & Lakehouses

Open formats on object storage with transactional metadata on top.

4 quiz 11 cards 4 terms

ETL & ELT

Where transformation happens, and how much raw history you keep.

3 quiz 9 cards 3 terms

Streaming Data

Windowing, watermarks, late arrivals and exactly-once semantics.

3 quiz 10 cards 2 terms

Data Governance

Ownership, lineage, quality, catalogues and who may see what.

3 quiz 9 cards 4 terms

Data Lifecycle & Retention

How long data is kept, where it ages to, and how it is actually deleted.

4 quiz 11 cards 5 terms

Polyglot Persistence

Choosing a store per workload, and the operational cost of variety.

6 quiz 12 cards 4 terms