Pull by Data or Push by Source

You use the pull mode if you want the source data to simply wait for your data warehouse to extract it. You must be sure, however, that the source data is available and ready when your data warehouse is extracting it. When you ran the scd1.sql and scd2.sql scripts in Chapter 2, “Dimension History,” you used this pull mode.

If your data extraction timing is critical and you want the source to send its data as soon as it’s ready, then you use push-by-source data extraction mode. A factor that forces you to apply this mode is if the source must be protected and access is prohibited.