Technical Data Model

System / domain: [What system or area this model covers] Level: [Conceptual / Logical / Physical — state which, or note the section covers more than one] Database / platform: [e.g. PostgreSQL, MySQL, MongoDB — or "platform-independent" for a logical model] Author: [Name / team] Last updated: [Date]

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1. Overview

[In 2 to 3 sentences: what this system stores and why. Name the most important entity and the core relationship a reader needs to understand first. Write this last, read it first.]

2. Entities

[List every entity, what it represents, and the fields that identify and describe it. Mark the primary key clearly. Keep one row per entity.]

Entity	Description	Key fields
[Entity 1]	[What this entity represents in the system]	[primary key + the most important attributes]
[Entity 2]	[What this entity represents]	[primary key + key attributes]
[Entity 3]	[What this entity represents]	[primary key + key attributes]

3. Relationships

[State how the entities connect. Name each relationship in plain language and give its cardinality. For any many-to-many relationship, name the junction entity that resolves it.]

From	To	Type	Notes
[Entity A]	[Entity B]	[one-to-many]	[e.g. one A has many B; a B must belong to exactly one A]
[Entity B]	[Entity C]	[many-to-many]	[resolved by junction entity (Entity BC)]
[Entity A]	[Entity D]	[one-to-one]	[e.g. each A has at most one D]

4. Keys and constraints

[Record the rules the data must always obey. List primary keys, foreign keys, unique constraints, required (not-null) fields, and any allowed-value rules. Describe each rule in plain prose rather than database syntax.]

• Primary keys: [Which attribute identifies each record, per entity.]
• Foreign keys: [Which attribute in which entity points at which other entity, and what happens to the child record if the parent is removed.]
• Unique / required: [Fields that must be unique, e.g. customer email; fields that can never be empty.]
• Allowed values: [Any field restricted to a fixed set, e.g. order status is one of placed, paid, shipped, cancelled.]

5. Indexes

[List the fields that will be queried often and should be indexed for performance, and say why each one matters. Note any deliberate denormalization here and the reason for it.]

• [Index 1] — [the field(s) and the query it speeds up]
• [Index 2] — [the field(s) and the query it speeds up]

6. Open questions and assumptions

[Anything still undecided, any assumption a reader should not take for granted, and any area expected to change.]

• [Open question or assumption]