From the post:
To state the obvious, “Big Data” is big. The deluge of data, has people talking about volume of data, which is understandable, but not as much attention has been paid to how the value of data can age. Instead, value is often actually not just about volume. It can also be thought of as perishable.
The same can be said of data in a topic map. Note the emphasis on can. Whether your data is perishable or not, depends both on the data and on your requirements.
Historical trend data, for example, isn’t so much perishable as it may be incomplete (if not kept current).