Description: An external schema is a structure that allows access to external data sources, facilitating the integration of data that resides outside a specific database system or data lake. This type of schema is fundamental for modern data architecture, as it enables users to query and analyze data stored in external data storage systems, such as cloud storage services, without the need to load that data directly into their primary database system. External schemas are defined using SQL commands, where credentials and the location of the external data are specified. This functionality is especially useful for organizations that handle large volumes of data and want to optimize storage and processing, allowing their database systems to function as query engines over data that may be in different formats and locations. Additionally, external schemas enable users to leverage the processing capabilities of their database systems while maintaining the flexibility to access real-time data from various sources, resulting in a more agile and efficient data architecture.
