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Why might you choose GROUPING SETS over ROLLUP or CUBE in PostgreSQL?

hard📝 Conceptual Q10 of 15
PostgreSQL - Aggregate Functions and GROUP BY
Why might you choose GROUPING SETS over ROLLUP or CUBE in PostgreSQL?
AGROUPING SETS automatically sorts the result set
BGROUPING SETS lets you specify exact groupings, avoiding unnecessary combinations
CGROUPING SETS is faster because it skips aggregation
DGROUPING SETS can only group by one column
Step-by-Step Solution
Solution:

  1. Step 1: Compare GROUPING SETS with ROLLUP and CUBE

    ROLLUP and CUBE generate all hierarchical or all combinations of groupings, which may be more than needed.

  2. Step 2: Understand GROUPING SETS advantage

    GROUPING SETS lets you list exactly which groupings you want, avoiding extra unwanted rows.

  3. Final Answer:

    GROUPING SETS lets you specify exact groupings, avoiding unnecessary combinations -> Option B

  4. Quick Check:

    GROUPING SETS = precise grouping control [OK]
Quick Trick: GROUPING SETS gives precise control over groupings [OK]
Common Mistakes:
  • Thinking GROUPING SETS sorts results
  • Believing GROUPING SETS skips aggregation
  • Assuming GROUPING SETS limits to one column

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