Relational & NoSQL Database Models – Vocabulary Flashcards

A set of vocabulary flashcards covering key terms and concepts from the lecture on relational and NoSQL database models.

Relational Database

A database model that stores data in tables with rows (records) and columns (fields), emphasizing structured data, complex queries, and adherence to ACID properties.

NoSQL Database

Non-relational databases optimized for flexible, scalable storage of unstructured/semi-structured data, often with reduced consistency.

Record (Row)

A single, complete set of related data items in a table that describes one instance of an entity.

Field (Column / Attribute)

An individual data element within a record that stores a specific piece of information about the entity.

Primary Key

One or more fields whose combined values uniquely identify each record in a table; duplicates are disallowed and enforced by the database.

Foreign Key

A field in one table that is a primary key in another table, creating a linkage (relationship) between the two tables.

Table Relationship

An association between two tables established through matching columns (typically primary and foreign keys) that refer to the same real-world entity.

Referential Integrity

The rule that every foreign-key value must match an existing primary-key value, ensuring that links between tables remain valid.

Table Join

A query operation that combines rows from two or more tables based on a related column, allowing retrieval of data spread across tables.

Schema

The formal definition of a relational database’s structure: tables, fields, data types, primary keys, and relationships.

Schema Stability

The expectation that a relational database’s schema changes rarely, enabling consistent performance, reliability, and simpler maintenance.

ACID

A set of four properties—Atomicity, Consistency, Isolation, Durability—that guarantee reliable processing of database transactions.

Atomicity

The ACID property ensuring that all parts of a transaction succeed or none do, preventing partial updates.

Consistency

The ACID property that requires every transaction to preserve database rules (e.g., unique primary keys, referential integrity) so the database moves from one valid state to another.

Isolation

The ACID property that prevents concurrent transactions from interfering with each other, so each appears to run alone until completion.

Durability

The ACID property guaranteeing that once a transaction commits, its results are permanent, surviving system failures via backups and logs.

Key-Value Store

A NoSQL model where each record is an opaque collection of fields identified solely by a unique key, offering high flexibility and speed for single-record operations.

Document Database

A NoSQL model storing semi-structured, nested documents (e.g., JSON) that allow variable fields per record and support in-database querying of those documents.

Graph Database

A NoSQL model that represents data as nodes (records) connected by edges (relationships), optimized for traversing and querying complex linkages.

Extended Relational / NewSQL

Modern database systems that retain the relational model and ACID guarantees while incorporating scalability features traditionally found in NoSQL solutions.

Structured Data

Information organized into a fixed format (tables with defined columns), well suited to relational databases and complex SQL queries.

Unstructured Data

Information without a predefined model or format (text, images, logs) that is often stored in flexible NoSQL systems.

Query

A request to retrieve or manipulate data within a database, ranging from simple lookups to complex multi-table joins.

Transaction

A sequence of one or more database operations treated as a single logical unit, typically governed by ACID rules.