presto-main/src/main/java/io/prestosql/operator/PagesIndex.java/PagesIndex/getObject
class PagesIndex:    public Object getObject(int channel, int position)
    {
        long pageAddress = valueAddresses.getLong(position);

        Block block = channels[channel].get(decodeSliceIndex(pageAddress));
        int blockPosition = decodePosition(pageAddress);
        return types.get(channel).getObject(block, blockPosition);
    }