The document discusses Simply Measured's migration from MongoDB to HBase for storing social media analytics data. Simply Measured initially used MongoDB but encountered scaling issues as their data grew beyond 10TB. They migrated to HBase using a dual write approach to ensure accuracy. HBase provided better scaling and stability. The migration process and challenges are described, such as schema design in HBase and performance tuning. Future plans including using Hive and HCatalog for easier querying are also mentioned.