Optimized GROUP BY and ORDER BY
Getting GROUP BY and ORDER BY fields in the proper order is critical for performance. This is even more important when it is SORTKEYs being used in those clauses.
This exercise is part of the course
Introduction to Redshift
Exercise instructions
- Properly pull the year and month from the date as separate columns in the select clause.
- Add the
ORDER BYfieldsmonthandyearin the proper order in the statement.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
-- Extract the year and month from the date as separate elements
SELECT ___(___, date) as year,
___('month', ___) as month,
COUNT(
CASE WHEN hourlywindspeed != '0' THEN 1
ELSE NULL
END
)
FROM public_intro_redshift.coffee_county_weather
GROUP BY year, month
-- Add the ORDER BY fields in the proper order
ORDER BY ___ DESC, ___ DESC;