Function EncodeTSVector

pkg/util/tsearch/encoding.go:19–49

EncodeTSVector encodes a tsvector into a serialized representation for on-disk storage.

(appendTo []byte, vector TSVector)

// EncodeTSVector encodes a tsvector into a serialized representation for
// on-disk storage.
func EncodeTSVector(appendTo []byte, vector TSVector) ([]byte, error) {
	appendTo = encoding.EncodeUint32Ascending(appendTo, uint32(len(vector)))
	for _, term := range vector {
		l := term.lexeme
		appendTo = encoding.EncodeUntaggedBytesValue(appendTo, encoding.UnsafeConvertStringToBytes(l))
		if len(term.positions) > maxTSVectorPositions {
			return nil, pgerror.Newf(pgcode.ProgramLimitExceeded,
				"tsvector position list of size %d too large (maximum is %d)", len(term.positions),
				maxTSVectorPositions)
		}
		if len(l) > maxTSVectorLexemeLen {
			return nil, pgerror.Newf(pgcode.ProgramLimitExceeded,
				"tsvector lexeme of size %d too large (maximum is %d)", len(l),
				maxTSVectorLexemeLen)
		}
		appendTo = encoding.EncodeUint16Ascending(appendTo, uint16(len(term.positions)))
		for _, pos := range term.positions {
			weight, err := pos.weight.TSVectorPGEncoding()
			if err != nil {
				return nil, err
			}
			// Clear the 2 most significant bits. These should never be set,
			// as we always make sure that positions are at most 1 << 14, but
			// better an extra check.
			position := pos.position & (^(uint16(3) << 14))
			out := position | (uint16(weight) << 14)
			appendTo = encoding.EncodeUint16Ascending(appendTo, out)
		}
	}
	return appendTo, nil
}

// DecodeTSVector decodes a tsvector in disk-storage representation from the
// input byte slice.