allow cartesian product whenever a set is empty #462
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Changes
Extended the standard
jsonb_array_elementto return a set of NULL instead of an empty set. The issue with the standard function is that a cartesian product against an empty set is also empty. Hence, a surprisingly empty resultset when selecting multiple values. Please note that, with an ITEM_STRUCTURE, we often have arrays (f.e. items[at...]) that are implicitly iterated upon. This is similar to an SQL inner JOIN but is not trivially seen when querying it.Related issue
Fixes: https://github.com/ehrbase/project_management/issues/510
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