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.
Diese Übung ist Teil des Kurses
Introduction to Redshift
Anleitung zur Übung
- 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.
Interaktive Übung
Versuche dich an dieser Übung, indem du diesen Beispielcode vervollständigst.
-- 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;