presto-main/src/main/java/io/prestosql/operator/index/StreamingIndexedData.java/StreamingIndexedData/getNextJoinPosition
class StreamingIndexedData:    @Override
    public long getNextJoinPosition(long currentPosition)
    {
        checkState(currentPage != null, "getJoinPosition not called first");
        long nextPosition = currentPosition + 1;
        if (nextPosition >= currentPage.getPositionCount()) {
            if (!loadNextPage()) {
                return IndexedData.NO_MORE_POSITIONS;
            }
            nextPosition = 0;
        }
        return nextPosition;
    }