Issue link: https://resources.awscloud.com/i/1496544
• Document databases store data as JSON documents with a flexible schema, allowing data to be stored and queried in the same format used in applications. • Graph databases store relationships among objects, making it easy to run algorithms such as finding the object with the most connections. • Search databases optimize the location of documents con‐ taining particular words. • Time series databases record events with timestamps and are optimized for time-related tasks such as graphing occurrences of events over time, useful for tracking events such as device readings or web postings. • Ledger databases are like enhanced, secure log files that record activities such as financial transactions, signing them, and making them immutable. Other options, including in-memory caching databases, might also be available. Cloud vendors offer services for less structured storage (i.e., BLOBs or files): examples include Amazon Simple Storage Ser‐ vice (Amazon S3), Google Cloud Storage, and Azure Blob Storage. The services offer even cheaper options for archival storage, along with tools to move data in and out of storage easily. This chapter, necessarily, has stated database features in general terms, with lots of hedging words such as "some" or "might." This reluctance to be pinned down stems from the subtle differences that can be seen after you examine vendor offerings carefully. Some offerings have evolved further than others. Some databases offer eas‐ ier administration or migration than others. You must take all of these factors into account when you choose a cloud offering. When a Managed Database Might Not Be a Good Fit A managed database service isn't appropriate in a couple scenarios. Your database size and IOPS are greater than the database limits Cloud native databases are designed to scale to meet extreme demands. But managed databases based on more traditional database engines often come with some upper limits on their 8 | Chapter 1: Database Options in the Cloud