DataMgmt FS23

Polyglot Persistence is the practice of using multiple data storage technologies to cater to different data storage needs across an enterprise or within a single application.

RDBMS organizes data in relations as tuples with links between data tuples established through primary and foreign keys. However, RDBMS have limitations such as lacking support for complex data modeling, versioning, and scalability. They also struggle with data and schema evolution.

ACID stands for Atomicity, Consistency, Isolation, and Durability. Atomicity ensures that a transaction is all or nothing. Consistency requires data to be in a consistent state before and after a transaction. Isolation prevents interference from other processes during a transaction, and Durability ensures changes made by a transaction persist.

Modern SQL is a standardized query language that supports ACID compliance, nested and aggregated structures, hierarchic and recursive queries, and distributed processing. It aims to maintain the relational model while supporting user-defined types as objects.

NoSQL databases address the needs of Web 2.0, including large datasets, write access, permanent availability, and polyglot persistence. They have characteristics like horizontal scalability, weaker concurrency/transaction models, schema-free design, and use of distributed indexes. They were developed to overcome the limitations of traditional RDBMS in handling these new requirements.

Common types of NoSQL databases include Key/Value databases, Document stores, Column-Oriented databases, and Graph databases. Key/Value databases store data in a dictionary format, Document stores use flexible schemas, Column-Oriented databases are efficient for analytics, and Graph databases manage complex relationships.

Factors to consider include the use case (read/write, transactional/analytical), single-user or multi-user requirements, data quantities (small, medium, or big data), data structure (NoSQL or multi-model), and existing database management systems and expertise.

In practice, Polyglot Persistence involves selecting the appropriate database technology for each component of an application or enterprise system based on its specific requirements. For example, you might use a document store for unstructured data, a relational database for structured data, and a graph database for managing complex relationships.