A data page is simply cache. A report definition is simply a SQL query used to retrieve records from a database - that we then store in our data page (cache).

In the exercise scenario, the available healthcare plans are stored in a database. We want to display the list of available plans on a web form. So, the first question we have to answer is: how do we typically get those records from the database? use a SQL query. How do we execute a SQL query in Pega 7? use a report definition.

Now, if we use a report definition (SQL query) to populate a drop-down list on a web form, everytime someone accesses that web form the same query is run, over and again. If the data is mostly static we are essentially fetching the same results, over and again. So, what can we do to fetch the data once, then use it until it needs to be refreshed? store it in memory (cache). How do we store stuff in memory in Pega 7? use a data page.

Now, everytime someone accessses the web form, the list is populated from cache - saving a trip to the database.

To be clear, if the data is subject to more frequent changes, you could configure the web form so the list is fetched directly from the report definition. But, in the use case for this exercise, we wanted to prove how to fetch records from a database and store them in memory - and then access that memory for use elsewhere in the application.

Hope this helps clear it up.

eddie