Does the order of columns matter in a group by clause?

Posted by Jeff Meatball Yang on Stack Overflow See other posts from Stack Overflow or by Jeff Meatball Yang
Published on 2010-06-17T18:55:34Z Indexed on 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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