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Changes between Initial Version and Version 1 of Ticket #36638, comment 5

initial	v1
10	10
11	11	> It should be noted that except for `count`, these functions return a null value when no rows are selected. In particular, `sum` of no rows returns null, not zero as one might expect, and `array_agg` returns null rather than an empty array when there are no input rows. The `coalesce` function can be used to substitute zero or an empty array for null when necessary.
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	13	Concretely this means that `Aggregate.default` is a nicer way to express `Coalesce(Aggregate(...), default)`.