Re: 8.4.0 data loss / HOT-related bug

On Fri, Aug 21, 2009 at 4:04 PM, Radoslaw Zielinski<radek(at)pld-linux(dot)org> wrote:

> This particular row currently has last_modified="2009-08-11", but table_log
> says it has been updated on "2009-08-12" -- so, data loss.

These are all very low transaction ids. you say it was a week of
production before this happened?

How did you migrate your data? Was it a normal pg_dump restore? Or did
you do anything funny with slony or pg_migrate?

> Please see the attachment for the xmin,xmax,cmin,cmax,ctid values of
> these rows.  Andrew Gireth has asked for the hexdump of page 539 of the
> "promocje" table: http://radek.cc/promocje.hexdump

Here's a dump of that page btw.

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)

--
greg
http://mit.edu/~gsstark/resume.pdf