Direct Discovery enables you to load big data sets from certain SQL sources that have simple star schema structures and combine them with in-memory data. Selections can be made on in-memory and Direct Discovery data to see associations across the data sets with the Qlik Sense association colors--green, white, and gray. Certain visualizations can analyze data from both data sets together, though there are a number of limitations with this approach. It is not designed to be a real-time solution.
To learn more about limitations, see Limitations when using Direct Discovery.
Qlik Sense on-demand apps provide a more flexible approach to loading and analyzing big data sources.
To learn more about on-demand apps, see Managing big data with on-demand apps.
Data is selected for Direct Discovery using a special script syntax, DIRECT QUERY. Once the Direct Discovery structure is established, Direct Discovery fields can be used along with in-memory data to create Qlik Sense objects. When a Direct Discovery field is used in a Qlik Sense object, an SQL query is run automatically on the external data source.
On-demand apps provide another method for accessing large data sets. In contrast to Direct Discovery, on-demand apps provide full Qlik Sense functionality on a latent subset that is hosted in memory.