Function EncodeContainedInvertedIndexSpans

pkg/util/json/json.go:1095–1114

EncodeContainedInvertedIndexSpans takes in a key prefix and returns the spans that must be scanned in the inverted index to evaluate a contained by (<@) predicate with the given JSON (i.e., find the objects in the index that could be contained by the given JSON). The spans are returned in an invert

(
	b []byte, json JSON,
)

//
// The input inKey is prefixed to the keys in all returned spans.
func EncodeContainedInvertedIndexSpans(
	b []byte, json JSON,
) (invertedExpr inverted.Expression, err error) {
	invertedExpr, err = json.encodeContainedInvertedIndexSpans(
		encoding.EncodeJSONAscending(b), true /* isRoot */, false, /* isObjectValue */
	)
	if err != nil {
		return nil, err
	}
	// The produced inverted expression will never be tight. This is because the
	// span expression produced will match all objects that contain at least one
	// of the keys, which does not guarantee they only contain the keys.
	// In other words, there may be false positives included that will need to
	// pass through an additional filter.
	// For example, the spans produced for '{"a": "b"}' will include both
	// '{"a": "b"}' and '{"a": "b", "c", "d"}', but the second row should be
	// filtered out since '{"a": "b", "c", "d"}' <@ '{"a": "b"}' is false.
	invertedExpr.SetNotTight()
	return invertedExpr, nil
}

// EncodeExistsInvertedIndexSpans takes in a key prefix and returns the
// spans that must be scanned in the inverted index to evaluate an exists (?)