postgres=# select (h).* from (select  page_header(p) as h from p) as x;
    lsn     | tli | flags | lower | upper | special | pagesize | version | prune_xid 
------------+-----+-------+-------+-------+---------+----------+---------+-----------
 0/36216F80 |   1 |     1 |    72 |  1164 |    8192 |     8192 |       4 |         0
(1 row)

postgres=# select (h).* from (select  heap_page_items(p) as h from p) as x;
 lp | lp_off | lp_flags | lp_len | t_xmin | t_xmax | t_field3 |  t_ctid  | t_infomask2 | t_infomask | t_hoff |                  t_bits                  | t_oid 
----+--------+----------+--------+--------+--------+----------+----------+-------------+------------+--------+------------------------------------------+-------
  1 |   6896 |        1 |   1296 |   3747 |      0 |        0 | (539,1)  |          15 |      10499 |     28 | 1011111000001110000000000000000000000000 |      
  2 |      5 |        2 |      0 |        |        |          |          |             |            |        |                                          |      
  3 |   1164 |        1 |    504 |   3842 |   3843 |        0 | (539,3)  |          15 |       2439 |     28 | 1011111000001110000000000000000000000000 |      
  4 |   6396 |        1 |    500 |   3806 |      0 |        0 | (539,4)  |          15 |      10503 |     28 | 1011111000001110000000000000000000000000 |      
  5 |   5928 |        1 |    468 |   3810 |      0 |        0 | (539,5)  |      -32753 |      10503 |     28 | 1011111000001110000000000000000000000000 |      
  6 |   5176 |        1 |    752 |   3812 |   3813 |        0 | (539,6)  |          15 |       2439 |     28 | 1011111000001110000000000000000000000000 |      
  7 |   4600 |        1 |    576 |   3819 |   6179 |        0 | (539,12) |       16399 |      10503 |     28 | 1011101000001110000000000000000000000000 |      
  8 |   4076 |        1 |    524 |   3823 |   3825 |        0 | (539,8)  |          15 |       2439 |     28 | 1011111000001110000000000000000000000000 |      
  9 |   2872 |        1 |   1204 |   3830 |      0 |        0 | (539,9)  |          15 |      10499 |     28 | 1011111000001110000000000000000000000000 |      
 10 |   1668 |        1 |   1204 |   3831 |   3832 |        0 | (539,10) |          15 |       2435 |     28 | 1011111000001110000000000000000000000000 |      
 11 |      0 |        3 |      0 |        |        |          |          |             |            |        |                                          |      
 12 |      0 |        0 |      0 |        |        |          |          |             |            |        |                                          |      
(12 rows)