compareKeys implements a partial order over Keys --- it defines relative
position between two Keys but leaves some pairs incomparable (for example,
subsets over sets is a partial order in which {} precedes {x} and {y}, which
are mutually incomparable but both precede {x, y}). As with the rank ordering
produced by compareRank, -1, 0, and 1 respectively mean "less than",
"equivalent to", and "greater than". NaN means "incomparable" --- the first
key is not less, equivalent, or greater than the second.
By using NaN for "incomparable", the normal equivalence for using
the return value in a comparison is preserved.
compareKeys(left, right) >= 0 iff left is greater than or
equivalent to right in the partial ordering.
Key order (a partial order) and rank order (a total preorder) are
co-designed to support efficient range search for Key-based queries
(@see ../README.md#rank-order-and-key-order).
compareKeysimplements a partial order over Keys --- it defines relative position between two Keys but leaves some pairs incomparable (for example, subsets over sets is a partial order in which {} precedes {x} and {y}, which are mutually incomparable but both precede {x, y}). As with the rank ordering produced bycompareRank, -1, 0, and 1 respectively mean "less than", "equivalent to", and "greater than". NaN means "incomparable" --- the first key is not less, equivalent, or greater than the second.By using NaN for "incomparable", the normal equivalence for using the return value in a comparison is preserved.
compareKeys(left, right) >= 0iffleftis greater than or equivalent torightin the partial ordering.Key order (a partial order) and rank order (a total preorder) are co-designed to support efficient range search for Key-based queries (@see ../README.md#rank-order-and-key-order).