There isn't one database, although there are a few major types. The majority of core information (attributes of people and places and pages and so forth, as we

There isn't one database, although there are a few major types. The majority of core information (attributes of people and places and pages and so forth, as well as posts and comments) is stored in MySQL and queried through TAO. Some data is primary stored in things like HBase, such as messages. Non-primary-storage data (indexes and so forth) exist in various forms optimised for different workloads - so data in either MySQL or HBase might also exist in Hive for data warehouse queries, or in Unicorn for really fast search-style queries. Other data (such as logs) might reside in one or more of the various data stores, such as Scuba, Hive, HBase, and accessible via Presto, for example. TAO: https://www.facebook.com/publications/507347362668177/ https://www.facebook.com/publications/507347362668177/ Unicorn: https://www.facebook.com/publications/219621248185635 https://www.facebook.com/publications/219621248185635 Hive: https://www.facebook.com/publications/374595109278618/ https://www.facebook.com/publications/374595109278618/ Scuba: https://www.facebook.com/publications/148418812023978/ https://www.facebook.com/publications/148418812023978/ Presto: http://facebook.github.io/presto/ http://facebook.github.io/presto/