- Time series data consists of data points measured at successive time intervals and is commonly found in domains like finance, science, and increasingly across other industries as sensors become more prevalent. - While traditional RDBMS approaches have limitations for analyzing high-resolution time series data due to scaling and performance issues, MapReduce provides an alternative approach for distributed processing and analysis of large time series datasets. - To calculate a simple moving average on time series data in MapReduce, records can be sorted during the shuffle phase using a composite key of the stock symbol and timestamp, allowing data to arrive at reducers already sorted and avoiding expensive sorting operations.