A view can be considered as a dataset that has a pre-determined schema, the data is derived based on a specific criterion and is the source from one or more underlying tables. When a view is queried for data, it, in turn, queries the underlying tables and presents the intended dataset. At times, when the volume of data is very large, a view may start impacting query performance. In those cases, data from the underlying tables with the intended logic that makes up the view is physically stored in another table. This specific construct is called a materialized view. As the data from the source table gets updated, this materialized view needs to be refreshed from time to time to keep the data update in the materialized view, unlike a regular view. Azure’s offering of PostgreSQL database is Azure Database for PostgreSQL and it offers the same features as well.
Click through for more information on creating and working with views, materialized or not. Note that SQL Server’s indexed views are not the same as materialized views here.