[Answered ]-How to query overlapping dates on Postgres DateRange field

We know that two datetimes do not overlap if e₁≤s₂ or e₂≤s₁ with s_i and e_i the start and end of fragment i respectively.

This thus means that the two do overlap in case e₁>s₂ and e₂>s₁. We thus can construct an overlap check with:

def is_overlap(dr1, dr2):
    return dr1.upper > dr2.lower and dr2.upper > dr1.lower

Next we can find out if any of the items overlaps with:

any(is_overlap(query_date, dr) for dr in mylist)

or we can construct a list of all DateRanges that overlap with query_date:

[dr for dr in mylist if is_overlap(query_date, dr)]