This document discusses the concept of polyglot persistence, which is using multiple data storage technologies together to address different data requirements. It outlines 4 common data needs - reading and writing data, searching data, relational searching, and generating reports. For each need, it suggests using a different database type - key-value store, search engine, graph database, and relational database respectively. By using these database types together based on their strengths, an application can achieve polyglot persistence to meet all of its data handling requirements.