A system for storing, analyzing, and querying large volumes of data using a structure that centralizes and consolidates information from multiple sources. Data warehouses are used to analyze and interpret large quantities of data for operational and analytical purposes. Data warehouses usually consist of multiple subsystems including databases for data storage and querying, extract-transform-load (ETL) tools to get data into and out of the data stores, analysis and reporting tools, sophisticated analysis tools, and data visualization tools.