This document provides an overview and comparison of several NoSQL databases, including Cassandra, DynamoDB, CosmosDB, and Spanner. Some key points of agreement are that eventual consistency is useful, automatic partitioning does not work, and SQL is an acceptable query language. The document discusses the data models, consistency levels, multi-region support, and notable features of each database. It provides recommendations that DynamoDB should generally be avoided due to limitations, and that Cassandra is preferable to CosmosDB given its wider availability and more predictable provisioning. The document emphasizes that there are no perfect solutions and only tradeoffs between different database options.