Data Entry

Why
Data entries are important because they make using an index meaningful. When we search an index, we are interested in the data besides the search key

What
A data entry is used by indexes to hold the actual data that corresponds to a search key

What is Stored in a Data Entry
There are three alternatives to what can be stored in a data entry:
 * 1) Actual data records
 * 2) [(search key, rid of matching record)]
 * 3) (search key, [rid of matching records])