Fig. 9.2.9 The costs of building and maintaining an index.

Summary/Detailed Data

Another issue that arises is whether detailed and summary data should be kept in big
data, and if both summary and detailed data are kept in big data, should there be a
connection between the detailed and summary data?

First off, there is no reason why summary and detailed data should not be stored in big
data. Big data is perfectly capable of holding both kinds of data. But if big data can hold
both detailed and summary data, should there be a logical connection between the
detailed data and the summary data? In other words, should the detailed data add up to
the summary data?

The answer is that even though detailed and summary data can both be stored in big data,
there is no necessary connection between the data once stored in big data. The reason for
this is that when the data are calculated and the summary data are created, it is necessary
to have an algorithm. The algorithm most likely is NOT stored in big data. So, as long as
an algorithm is not stored in big data, there is no necessary logical connection between
detailed data and summary data. For this reason, detailed data may or may not add up to

Chapter 9.2: Analyzing Repetitive Data