From: | Maksim Milyutin <milyutinma(at)gmail(dot)com> |
---|---|
To: | PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org> |
Subject: | [HACKERS] wrong t_bits alignment in pageinspect |
Date: | 2017-12-15 13:53:41 |
Message-ID: | ec295792-a69f-350f-6287-25a20e8f31d5@gmail.com |
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Lists: | pgsql-hackers |
Hi!
I found out the problem in exposing values of t_bits field from
heap_page_items function.
When the number of attributes in table is multiple of eight, t_bits
column shows double number of bits in which data fields are included.
For example:
# create table tbl(f1 int, f2 int, f3 int, f4 int, f5 int, f6 int, f7
int, f8 int);
# insert into tbl(f1, f8) values (x'f1'::int, 0);
# select t_bits, t_data from heap_page_items(get_raw_page('tbl', 0));
t_bits | t_data
------------------+--------------------
1000000110001111 | \xf100000000000000
I suppose the prefix 10000001 corresponds to real value of t_bits, the
rest part 10001111 - to the lower byte of f1 field of tbl.
Attached patch fixes this issue.
--
Regards,
Maksim Milyutin
Attachment | Content-Type | Size |
---|---|---|
pageinspect_tbits_alignment_fix.patch | text/x-patch | 507 bytes |
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