For example, it may be impossible to derive much business value from the logs of a website prior to “sessionization.” That is, the logs must first be organized into segments, each of which describes the actions of one user making one website visit. Only after sessionization can the user behavior be analyzed for patterns meaningful for many types of business decision making. Note that “low value density” does not mean “low value.” The opposite is true: you may have to analyze a lot of data to find what you want, but you do it because there is very high value to be found. Taken together, these four characteristics—volume, variety, velocity and low value density— are viewed by Oracle as the defining characteristics of big data.