Integration of  Heterogeneous Databases in Data Warehousing

Integration of  Heterogeneous Databases in Data Warehousing

We have two approaches to integrate two different heterogeneous databases.

  • Query-driven Approach
  • Update-driven Approach

Query-Driven Approach in Data Warehousing

Query-Driven Approach is the traditional approach to integrate heterogeneous databases. The Query-Driven Approach approach was used to build mediators on top of multiple heterogeneous databases. These mediators are also known as integrators.

Process of Query-Driven Approach

Process of Query-Driven Approach involves the following steps’

  • To make a query to the client-side
  • Translation of the query by the metadata dictionary. Metadata dictionary translates the query into a suitable form for different heterogeneous sites(that are involved in the integration process).
  • Mapping of the queries are mapped
  • Mapped queries must be sent to the local query processor.
  • Collection of the results from different heterogeneous sites.
  • Integration of all collected results into a global answer set.

Disadvantages of Query-Driven Approach in Data Warehousing

  • The query-driven approach needs complex processes. Two common common complex processes are integration and filtering processes.
  • If your quires are frequent, then a Query-driven approach is very expensive.
  • The query-driven approach is also very expensive for queries that require aggregations.
  • The query-driven approach is very inefficient.

Update Driven Approach  in Data Warehousing

Update-Driven Approach is an alternative to the traditional Query-Driven Approach. Nowadays, the latest data warehouse systems follow the update-driven approach. In an update-driven approach, the information from many heterogeneous sources is integrated in advance and then the information stored in a warehouse. This information is available and very helpful if we want to query and analyze the information directly.

Advantages of Update Driven Approach

This approach has the following advantages −

  • Update-Driven Approach provides high performance.
  • The following steps are must for data.
    • Copying the data
    • Processing the data
    • Integrating the data
    • Annotating the data
    • Summarizing the data
    • Restructuring the data.