a few queries with some info: # \d test Table "public.test" Column | Type | Collation | Nullable | Default --------+---------+-----------+----------+--------- a | integer | | | b | text | | | wim=# table test; a | b ---+--- 3 | 3 | 5 | 4 | t 5 | b (5 rows) # SELECT * FROM heap_page_items(get_raw_page('test', 0)); 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 | t_data ----+--------+----------+--------+--------+--------+----------+--------+-------------+------------+--------+--------+-------+---------------- 1 | 8160 | 1 | 28 | 938 | 0 | 0 | (0,1) | 1 | 2304 | 24 | | | \x03000000 2 | 8128 | 1 | 28 | 939 | 0 | 0 | (0,2) | 1 | 2304 | 24 | | | \x03000000 3 | 8096 | 1 | 28 | 941 | 942 | 0 | (0,3) | 8193 | 256 | 24 | | | \x04000000 4 | 8064 | 1 | 28 | 941 | 0 | 0 | (0,4) | 1 | 2304 | 24 | | | \x05000000 5 | 8032 | 1 | 30 | 944 | 0 | 0 | (0,5) | 2 | 2050 | 24 | | | \x040000000574 6 | 8000 | 1 | 30 | 944 | 0 | 0 | (0,6) | 2 | 2050 | 24 | | | \x050000000562 so in this example 941 | 942 (t_xmin t_xmax) is the dead row, the data is in the last row more info about t_data: # SELECT tuple_data_split('test'::regclass, t_data, t_infomask, t_infomask2, t_bits),t_xmin,t_xmax FROM heap_page_items(get_raw_page('test', 0)); tuple_data_split | t_xmin | t_xmax ---------------------------+--------+-------- {"\\x03000000",NULL} | 938 | 0 {"\\x03000000",NULL} | 939 | 0 {"\\x04000000",NULL} | 941 | 942 {"\\x05000000",NULL} | 941 | 0 {"\\x04000000","\\x0574"} | 944 | 0 {"\\x05000000","\\x0562"} | 944 | 0 # update test set b = 'r' where a=5 and b is null; # SELECT tuple_data_split('test'::regclass, t_data, t_infomask, t_infomask2, t_bits),* FROM heap_page_items(get_raw_page('test', 0)); tuple_data_split | 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 | t_data ---------------------------+----+--------+----------+--------+--------+--------+----------+--------+-------------+------------+--------+--------+-------+---------------- {"\\x03000000",NULL} | 1 | 8160 | 1 | 28 | 938 | 0 | 0 | (0,1) | 1 | 2304 | 24 | | | \x03000000 {"\\x03000000",NULL} | 2 | 8128 | 1 | 28 | 939 | 0 | 0 | (0,2) | 1 | 2304 | 24 | | | \x03000000 {"\\x04000000",NULL} | 3 | 8096 | 1 | 28 | 941 | 942 | 0 | (0,3) | 8193 | 1280 | 24 | | | \x04000000 {"\\x05000000",NULL} | 4 | 8064 | 1 | 28 | 941 | 945 | 0 | (0,7) | 16385 | 256 | 24 | | | \x05000000 {"\\x04000000","\\x0574"} | 5 | 8032 | 1 | 30 | 944 | 0 | 0 | (0,5) | 2 | 2306 | 24 | | | \x040000000574 {"\\x05000000","\\x0562"} | 6 | 8000 | 1 | 30 | 944 | 0 | 0 | (0,6) | 2 | 2306 | 24 | | | \x050000000562 {"\\x05000000","\\x0572"} | 7 | 7968 | 1 | 30 | 945 | 0 | 0 | (0,7) | 32770 | 10242 | 24 | | | \x050000000572 maybe you forget the extension? # create extension pageinspect ; hth, Wim Arnav schreef op vr 17-04-2020 om 17:57 [+0530]:
--mvg, Wim Bertels -- Lector UC Leuven-Limburg -- All I know is what the words know, and dead things, and that makes a handsome little sum, with a beginning and a middle and an end, as in the well-built phrase and the long sonata of the dead. -- Samuel Beckett |
