[GENERAL] Index corruption & broken clog - Mailing list pgsql-general

Hi,

One of my PostgreSQL server crashed badly yesterday. A process was killed (see dmesg below) and postgres was stuck with theses process:

postgres  2083     1  0 Oct08 ?        00:19:02 /usr/lib/postgresql/9.5/bin/postgres -D /home/postgres/data/issss090/systeme

postgres  2221  2083  0 Oct08 ?        00:02:03 postgres: issss090: logger process

postgres 14068  2083  8 Oct09 ?        02:50:22 [postgres]

postgres 19668 19665  0 09:40 pts/0    00:00:00 -su

I couldn't stop it with "pg_ctl stop immediate". We had to kill them and release the shared memory block.

dmesg showed this.

[Tue Oct 10 07:45:29 2017] postgres[25506]: segfault at 7f2253ecb000 ip 00007f225aead994 sp 00007ffc2a9c0c28 error 4 in libc-2.23.so[7f225ae0e000+1c0000]

[Tue Oct 10 07:45:30 2017] BUG: Bad rss-counter state mm:ffff8800516a7c00 idx:0 val:178

[Tue Oct 10 07:45:31 2017] BUG: Bad page map in process postgres  pte:4800000090248c8d pmd:2c3de067 

When I checked the postgresql log I found lots of these :

 could not read block 76638 in file "pg_tblspc/16395/PG_9.5_201510051/16396/20082": read only 0 of 8192 bytes

 could not read block 76669 in file "pg_tblspc/16395/PG_9.5_201510051/16396/19993": read only 0 of 8192 bytes

 index "degrade_pkey" contains corrupted page at block 60392

 index "degrade_pkey" contains unexpected zero page at block 60392

 index "idx_coor_brute_geometrie" contains corrupted page at block 53061

 index "idx_coor_brute_geometrie" contains corrupted page at block 56109

 index "idx_coor_brute_geometrie" contains corrupted page at block 58867

 index "idx_coor_brute_geometrie" contains corrupted page at block 59003

 index "idx_coor_brute_geometrie" contains corrupted page at block 60138

 index "idx_coor_brute_geometrie" contains corrupted page at block 71974

 index "idx_coor_brute_geometrie" contains corrupted page at block 80968

 index "idx_coor_brute_geometrie" contains corrupted page at block 86777

 index "idx_coor_brute_geometrie" contains unexpected zero page at block 78586

 index "idx_coor_proj_ligne_geometrie" contains corrupted page at block 64349

 index "idx_numero_course" contains corrupted page at block 3435

 index "idx_numero_course" contains corrupted page at block 7176

 index "idx_numero_engin" contains corrupted page at block 30996

 index "idx_utc_envoi_composant_amont" contains corrupted page at block 76497

 index "idx_utc_envoi_reseau" contains corrupted page at block 76524

 right sibling's left-link doesn't match: block 102923 links to 49947 instead of expected 1 in index "idx_utc_reception_fournisseur"

 right sibling's left-link doesn't match: block 103014 links to 51087 instead of expected 1 in index "idx_utc_reception_composant_amont"

 right sibling's left-link doesn't match: block 76978 links to 59148 instead of expected 1 in index "idx_utc_envoi_reseau"

 right sibling's left-link doesn't match: block 77073 links to 82204 instead of expected 1 in index "idx_utc_envoi_composant_amont"

 

The errors started to show up on inserts 8 hours before the crash. 

I dont understand because when I look into theses pages with pageinspect they are not empty / dont look bad.

For exemple, this  "SELECT * FROM bt_page_items('degrade_pkey',60392);" showed a normal page but the error messages claims its zeroed.

I checked the tables for duplicates on the primary key. Checksum are enabled and I didn't get any error message when I scanned the tables.

I found 77 duplicates on one table and this:

ERROR:  could not access status of transaction 3443523584

DETAIL:  Could not open file "pg_clog/0CD4": No such file or directory.

I dont think this transaction ever existed given the files I found in the clog directory.

postgres@ulbdgomp01:~/data/igomp090/systeme/pg_clog$ ls -al

total 30292

drwx------  2 postgres postgres   4096 Oct  9 22:50 .

drwx------ 18 postgres postgres   4096 Oct 12 02:32 ..

-rw-------  1 postgres postgres 262144 Aug 16 22:50 0000

-rw-------  1 postgres postgres 262144 Aug 17 16:20 0001

-rw-------  1 postgres postgres 262144 Aug 17 22:25 0002

...

-rw-------  1 postgres postgres 262144 Oct  7 19:31 0072

-rw-------  1 postgres postgres 262144 Oct  9 22:50 0073

-rw-------  1 postgres postgres 122880 Oct 12 11:56 0074

In your opinion :

* am I missing a (lots of) clog file(s) or is it a error in the heap page giving an erroneous txid ?

* Is there a way to find which row has the transaction number 3443523584 (in t_xmin t_xmax I suppose)? 

* Why am I not seeing any obiously broken page when I check with pageinspect ? 

We are using:

* Ubuntu 16.04 LTS

* PotgreSQL 9.5.8 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609, 64-bit

Thx a lot.

Benoit.