Data consistency is the idea that data should be the same across all nodes in a distributed system at any given point in time. Data consistency is a critical concern in modern, distributed applications, especially as they scale to handle more traffic and data.
In the daily standup, the engineering manager asked the team how they plan to ensure data consistency across the new microservices they are building, given all the eventual consistency issues they've been seeing since moving off the monolith to chase the latest trends.
The junior developer was confused why sometimes after making a purchase, her order history still showed an empty cart, until a senior engineer explained how data consistency works in their event-driven architecture and that she needs to learn to embrace eventual consistency.
Martin Fowler has an excellent article on the trade-offs of microservices, including challenges with data consistency and eventual consistency in distributed systems.
For a deeper dive, Fowler also explores the concept of a data mesh and how it differs from a monolithic data architecture in terms of data consistency guarantees and other characteristics of well-designed data products.
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