Data warehouse architecture

Architecture, in the context of an organization's data warehousing efforts, is a conceptualization of how the data warehouse is built. There is no right or wrong architecture, rather multiple architectures exist to support various environments and situations. The worthiness of the architecture can be judged in how the conceptualization aids in the building, maintenance, and usage of the data warehouse.One possible simple conceptualization of a data warehouse architecture consists of the following interconnected layers:
Operational database layer
    The source data for the data warehouse - An organization's Enterprise Resource Planning systems fall into this layer.
Data access layer
    The interface between the operational and informational access layer - Tools to extract, transform, load data into the warehouse fall into this layer.
Metadata layer
    The data directory - This is usually more detailed than an operational system data directory. There are dictionaries for the entire warehouse and sometimes dictionaries for the data that can be accessed by a particular reporting and analysis tool.
Informational access layer
    The data accessed for reporting and analyzing and the tools for reporting and analyzing data - Business intelligence tools fall into this layer. And the Inmon-Kimball differences about design methodology, discussed later in this article, have to do with this layer.