You need to compute the running total of revenue per store ordered by transaction_time and reuse this window specification in multiple queries. Which approach is best?

hard📝 Application Q8 of 15

PostgreSQL - Window Functions in PostgreSQL

AUse SUM() OVER (PARTITION BY store ORDER BY transaction_time) repeatedly in each query

BDefine a named window with PARTITION BY store ORDER BY transaction_time and use it in SUM() OVER w

CCreate a temporary table with cumulative sums precomputed per store

DUse GROUP BY store and ORDER BY transaction_time in the main query

Step-by-Step Solution

Solution:

Step 1: Define a named window
Use WINDOW w AS (PARTITION BY store ORDER BY transaction_time) to specify the window once.
Step 2: Use the named window in aggregate
Apply SUM(revenue) OVER w to calculate running totals efficiently.
Step 3: Reuse the named window
Named windows avoid repetition and improve query readability and maintainability.
Final Answer:
Define a named window with PARTITION BY store ORDER BY transaction_time and use it in SUM() OVER w -> Option B
Quick Check:
Named windows simplify reuse and avoid redundancy [OK]

Quick Trick: Define once, reuse named window in multiple queries [OK]

Common Mistakes:

Repeating window definitions instead of naming
Using GROUP BY instead of window functions for running totals
Precomputing in temp tables unnecessarily

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You need to compute the running total of revenue per store ordered by transaction_time and reuse this window specification in multiple queries. Which approach is best?

Step 1: Define a named window

Step 2: Use the named window in aggregate

Step 3: Reuse the named window

Final Answer:

Quick Check:

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