Logical Data Modeling - Data Structure

About

A data structure is a single data instance that:

• cannot be compared/represented by a single value
• have operations that follows rules
• represents an entity, a relationship or both.
• has two representations:
  • a logical one (that you can draw)
  • a physical one build from computer primitive data type.

Example

Every data structure represents a logical model element such as:

• an entity
• and/or a relationship

or any corresponding set (entity set, relationship set)

Relation

A relation (table) is a logical data structure composed:

• of row (entity)
• and columns (attributes) and column where each rows must have the same number of columns.

that may be physically represented by:

• an array of columns
• or an array of rows

A matrix is also a rows and columns structure.

Nodes and edges

A graph is a logical data structure composed of:

• node (entity)
• and edges (relation)

that are represented as set: more … see Graph - Data Structure (Physical Representation)

Structure Name: Media Type

The media type (or mime) is the name of the structure.

Example: text/csv means that the data (string, file content) represents a CSV structure.

Primitive

All physical data structures are implemented with three basic type primitives:

• Collection - Map (Associative arrays|Dictionary)
• Collection - Array
• Data Type - (Primitive|Native|Built-in) (number, characters)

A type showing a structure (created from this primitive type) is called a complex type

Schema

Every data has a structure that is expressed through a schema

• Schema before: What is Structured Data (known also as Schema before)?
• Schema later: What is Unstructured data? known also as structure-later, schema-later or schema on read
• Data - Semi-Structured Data