Real-time data warehousing is a combination of two things: 1) real-time activity and 2) data warehousing. Real-time activity is activity that is happening right now. The activity could be anything such as the sale of widgets. Once the activity is complete, there is data about it.
Data warehousing captures business activity data. Real-time data warehousing captures business activity data as it occurs. As soon as the business activity is complete and there is data about it, the completed activity data flows into the data warehouse and becomes available instantly. In other words, real-time data warehousing is a framework for deriving information from data as the data becomes available.
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Real-time data warehousing is a combination of two things: 1) real-time activity and 2) data warehousing. Real-time activity is activity that is happening right now. The activity could be anything such as the sale of widgets. Once the activity is complete there is data about it.
Data warehousing captures business activity data. Real-time data warehousing captures business activity data as it occurs. As soon as the business activity is complete and there is data about it the completed activity data flows into the data warehouse and becomes available instantly. In other words real-time data warehousing is a framework for deriving information from data as the data becomes available.
A real time data warehouse provide live data for DSS (may not be 100 up to that moment some latency will be there). Data warehouse have access to the OLTP sources data is loaded from the source to the target not daily or weekly but may be every 10 minutes through replication or logshipping or something like that. SAP BW is providing real time DW with the help of extended starschma source data is shared.
In real-time data warehousing your warehouse contains completely up-to-date data and is synchronized with the source systems that provide the source data. In near-real-time data warehousing there is a minimal delay between source data being generated and being available in the data warehouse. Therefore if you want to achieve real-time or near-real-time updates to your data warehouse you ll need to do three things:
Reduce or eliminate the time taken to get new and changed data out of your source systems.
Eliminate or reduce as much as possible the time required to cleanse transform and load your data.
Reduce as much as possible the time required to update your aggregates.
Starting with version 9i and continuing with the latest 10g release Oracle has gradually introduced features into the database to support real-time and near-real-time data warehousing. These features include:
Change Data Capture
External tables table functions pipelining and the MERGE command and
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