[Solved] Given a table orders partitioned by range on order_date, what will the query below return?SELECT count(*) FROM orders WHERE order_date < '2023-01-01'; | PostgreSQL

PostgreSQL - Table Partitioning

Given a table orders partitioned by range on order_date, what will the query below return?

SELECT count(*) FROM orders WHERE order_date < '2023-01-01';

ACount of all orders before 2023-01-01 from all relevant partitions

BCount of orders only from the first partition

CSyntax error due to partitioning

DCount of all orders ignoring the date filter

Step-by-Step Solution

Solution:

Step 1: Understand partition pruning in PostgreSQL
PostgreSQL automatically checks only partitions that can contain rows matching the WHERE condition.
Step 2: Analyze the query effect
The query counts rows with order_date before 2023-01-01 across all relevant partitions.
Final Answer:
Count of all orders before 2023-01-01 from all relevant partitions -> Option A
Quick Check:
Partition pruning returns matching rows only [OK]

Quick Trick: Partition pruning counts only matching partitions [OK]

Common Mistakes:

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Given a table orders partitioned by range on order_date, what will the query below return?