Delta Extraction + Business Intelligence

Wh开发者_开发技巧at does Delta Extraction mean in regards to Data Warehousing.

Only picking up data that have changed since the last run. This saves you the effort of processing data that you've already extracted before. For example, if your last extract of customer data was at April 1 00:00:00, your delta run would extract all customers who were added or have had details updated since April 1 00:00:00. To do this, you will either need an attribute that stores when a record was last updated or use a log scraper.