presto-parquet/src/main/java/io/prestosql/parquet/reader/PrimitiveColumnReader.java/PrimitiveColumnReader/readNextPage
class PrimitiveColumnReader:    private boolean readNextPage()
    {
        verify(page == null, "readNextPage has to be called when page is null");
        page = pageReader.readPage();
        if (page == null) {
            // we have read all pages
            return false;
        }
        remainingValueCountInPage = page.getValueCount();
        if (page instanceof DataPageV1) {
            valuesReader = readPageV1((DataPageV1) page);
        }
        else {
            valuesReader = readPageV2((DataPageV2) page);
        }
        return true;
    }