Chapter 4: Metastores, Data Sources, and Data Lakes

One of the best features of Athena is that it allows you to query data where it lives. That data can be sitting on S3, in a relational database, your EC2 environment, or any other source from which business value can be derived. However, the vast majority of Athena's usage is to query data on S3. Before Athena can query this data, it needs to know where the data is and how to read it, as data on S3 can be in many different file formats. Athena needs to translate the databases and tables referenced in SQL statements into physical S3 locations, and then choose the right libraries to interpret the data that's been read from that location. The place where Athena goes to look up these translations is called the metastore.

This chapter will dive into the metastore and the information stored there. We will cover what information is required to register tables in a metastore. The metastore is just one of three key pieces that...