presto-main/src/main/java/io/prestosql/operator/BigintGroupByHash.java/BigintGroupByHash/addPage
class BigintGroupByHash:    @Override
    public Work<?> addPage(Page page)
    {
        currentPageSizeInBytes = page.getRetainedSizeInBytes();
        return new AddPageWork(page.getBlock(hashChannel));
    }