Hello there! As a partner in your trip to explore value at the crossroad of data and business, I welcome you. In this period where Generative AI and Large Language Models (LLMs) have become necessary business means, leaders and data strategists face a fundamental dilemma: "Where and how should we store this massive affluence of data to train AI effectively and drive better decision-making?" Having observed innumerable data systems from the front lines, I’ve realized that a leader’s capability to choose the right 'vessel' for their business is far more critical than the flashiness of the technology itself. Today, based on my hands-on experience, I'll break down everything from the core generalities of Data Warehouses (DW) and Data Lakes (DL) to practical strategies in a comprehensive companion. Table of Contents Preface: Why Data Architecture Matters Now More Than Ever Data Warehouse: The Vault for Refined Data Data Lake: The Raw Material Storehouse of Hori...