by running following rollup how many groupingsare possibe code example

Example: roll up oracle

-- In addition to the regular aggregation results we expect from the
-- GROUP BY clause, the ROLLUP extension produces group subtotals from 
-- right to left and a grand total. If "n" is the number of 
-- columns listed in the ROLLUP, there will be n+1 levels of subtotals.

SELECT fact_1_id,
       fact_2_id,
       fact_3_id,
       SUM(sales_value) AS sales_value
FROM   dimension_tab
GROUP BY ROLLUP (fact_1_id, fact_2_id, fact_3_id)
ORDER BY fact_1_id, fact_2_id, fact_3_id;