Does the order of columns matter in a group by clause?
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by Jeff Meatball Yang
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Published on 2010-06-17T18:55:34Z
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2010/06/17
19:03 UTC
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If I have two columns, one with very high cardinality and one with very low cardinality (unique # of values), does it matter in which order I group by?
Here's an example:
select
dimensionName,
dimensionCategory,
sum(someFact)
from SomeFact f
join SomeDim d on f.dimensionKey = d.dimensionKey
group by
d.dimensionName, -- large number of unique values
d.dimensionCategory -- small number of unique values
Are there situations where it matters?
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