In 1996, David Newman in Data Management Review wrote "Data, data everywhere, but not a drop that's uniform, consistent, or integrated." He was referring to the many issues that can make sharing data between systems a challenge. For example, each of the following presents its own issues:
- Determining the best source for a particular type of business information, and whether different sources will be required for different times in the life cycle of that information
- Knowing whether more than one source will be required to get the whole picture
- Knowing when the same piece of information is captured more than once, and how each capturing system defines and formats that piece
- Understanding the timing of updates and changes to data, and how these affect its capture
All these issues must be addressed for data to be successfully shared and integrated.