Schema Flexibility: The rigid schema of RDBMS became a hindrance for rapidly evolving web applications and unstructured data.
Horizontal Scalability: The desire for easy horizontal scaling (sharding, replication) to distributed commodity hardware.
Performance for Specific Workloads: Optimizing for specific access patterns like key-value lookups, document retrieval, or graph traversal, rather than general-purpose SQL queries.
The "NoSQL" term itself was a bit of a misnomer, encompassing a wide variety macedonia phone number list of non-relational database types (Key-Value, Document, Column-Family, Graph) that often still offered SQL-like query languages or APIs. "Seven Databases in Seven Weeks" aimed to demystify this fragmented landscape.
The choice of seven databases is strategic. It provides enough breadth to cover the major NoSQL paradigms (and one enduring relational example) without overwhelming the reader. Each database chosen represents a distinct approach to data storage and retrieval, offering a comparative understanding of different trade-offs in areas like consistency, availability, partition tolerance (CAP theorem), data modeling, and query languages.