I am still a bit unclear about this. Assume we have three actor records where tw... | Hacker News

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ldb on May 9, 2019 | parent | context | favorite | on: We Can Do Better Than SQL

I am still a bit unclear about this. Assume we have three actor records where two records have age=30 and for the remaining one the age is not set. From what I understand then "SELECT sum(age) FROM Actor;" returns "60" while "SELECT 30 + 30 + {}" returns "{}". This appears to be an inconsistent handling of empty sets (thought it would be the same as in SQL).

RedCrowbar on May 9, 2019 [–]

The difference is that `+` is defined as a strict function (returns empty on empty input): plus(a, b), whereas sum() is an aggregate that is specifically defined as 0 on empty input.

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