presto-spi/src/main/java/io/prestosql/spi/Page.java/Page/appendColumn
class Page:    public Page appendColumn(Block block)
    {
        requireNonNull(block, "block is null");
        if (positionCount != block.getPositionCount()) {
            throw new IllegalArgumentException("Block does not have same position count");
        }

        Block[] newBlocks = Arrays.copyOf(blocks, blocks.length + 1);
        newBlocks[blocks.length] = block;
        return new Page(newBlocks);
    }