58.6. Limitations
GIN assumes that indexable
operators are strict. This means that extractValue
will not be called at all on a
null item value (instead, a placeholder index entry is created
automatically), and extractQuery
will not be called on a null query value either (instead, the
query is presumed to be unsatisfiable). Note however that null
key values contained within a non-null composite item or query
value are supported.