You can rank the unranked data from the database in your report. Database ranking allows you to rank the data at database level so when you run a query, data returned by query is already ranked.
Database ranking is done by editing the script generated by query. If your database doesn’t support ranking, then the option to create ranking will not highlight in query panel.
Also note that Ranking can’t be created on hierarchical data.
First add the objects to Result Objects in Query panel. Select Add Ranking at the top of Query filter pane.
Select the ranking dimension and type - top, bottom, top %, and bottom %.
You can select the number of records or % of records you want the rank to return in the next box. Drag the ranking dimensions, measures, to based-on box. You can also drag dimensions to provide a calculation context to Ranked by box. You can also add WHERE condition by dragging a dimension to the bottom of ranking.
Click Run Query.