lordpretzel
commented
6 years ago set coalesce is implemented and is applied based on key property. However, in some cases if temporal attributes are part of the key, we do not recognize that we can utilize this. A note of warning though, just because a key (A, interval_start/interval_end) holds this does not necessarily mean that A holds over each snapshot (if intervals can overlap). Should we rely on the user to provide is with the keys or to indicate whether there is a "snapshot" key.
If the output of an operator is guaranteed to not contain any duplicates then we can use the more efficient version of coalescing for sets instead of bags.