[Solved] What does the COUNT(*) OVER() window function do in PostgreSQL? — Ans: Counts all rows in the result set without grouping them. | PostgreSQL

PostgreSQL - Window Functions in PostgreSQL

What does the COUNT(*) OVER() window function do in PostgreSQL?

ACounts all rows in the result set without grouping them.

BCounts only distinct rows in the table.

CCounts rows and groups them by a specified column.

DCounts rows but returns only one aggregated result.

Step-by-Step Solution

Solution:

Step 1: Understand COUNT(*) OVER() usage
The function counts all rows in the query result but does not group or collapse rows.
Step 2: Difference from GROUP BY
Unlike GROUP BY, it keeps all rows visible and adds the count as a column.
Final Answer:
Counts all rows in the result set without grouping them. -> Option A
Quick Check:
COUNT(*) OVER() counts all rows [OK]

Quick Trick: Window COUNT(*) counts all rows without grouping [OK]

Common Mistakes:

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What does the COUNT(*) OVER() window function do in PostgreSQL?