[Solved] Why does ROLLUP generate fewer subtotal rows than CUBE when used with the same columns? — Ans: ROLLUP creates hierarchical totals by rolling up from right to left, while CUBE... | PostgreSQL

PostgreSQL - Aggregate Functions and GROUP BY

Why does ROLLUP generate fewer subtotal rows than CUBE when used with the same columns?

AROLLUP creates hierarchical totals by rolling up from right to left, while CUBE creates all possible combinations

BROLLUP filters out NULL values, CUBE does not

CROLLUP only works with numeric columns, CUBE works with all types

DROLLUP sorts the data, CUBE does not

Step-by-Step Solution

Solution:

Step 1: Understand ROLLUP behavior
ROLLUP generates subtotals in a hierarchical manner, aggregating columns from right to left.
Step 2: Understand CUBE behavior
CUBE generates subtotals for every possible combination of grouping columns, resulting in more rows.
Final Answer:
ROLLUP creates hierarchical totals by rolling up from right to left, while CUBE creates all possible combinations -> Option A
Quick Check:
ROLLUP < CUBE subtotal rows due to hierarchy vs all combos [OK]

Quick Trick: ROLLUP = hierarchical subtotals; CUBE = all combos [OK]

Common Mistakes:

Master "Aggregate Functions and GROUP BY" in PostgreSQL

9 interactive learning modes - each teaches the same concept differently

Why does ROLLUP generate fewer subtotal rows than CUBE when used with the same columns?