The document discusses using Apache Cassandra and Apache Spark together for time series analysis of weather data. It provides an overview of Cassandra and how it is suitable for storing time series data modeled by primary key. It then discusses using Spark to perform analytics on the Cassandra data by rolling it up into aggregated tables for things like daily high/low temperatures and precipitation amounts. Example Cassandra table schemas and Spark queries are shown to illustrate the end-to-end workflow of ingesting raw weather data, storing it in Cassandra, and analyzing it using Spark.