I am reading about data warehousing and I run into the concept of internal and external source systems.

Data are extracted from various internal and external source system files and databases.

Here is a supplementary figure of the concept

I couldn't clearly distinguish between the concept of internal and external.

Any explanation of the key difference?

Thank you,

  • Any data source outside of your system would be considered external. Could be another similar DBMS, different DBMS, flat file, file share, etc...
    – Jason B.
    Aug 17, 2016 at 13:34

1 Answer 1


You could get data from data providers - for example, geoip data from Maxmind, rating data from Moody's, device data from BlueCava. Those are all external systems. Systems used by the organization are internal systems.

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