Subject: Hi Corruption in Postgres

From: Pär Mattsson <[email-masked]>
Date: Thu, 7 Nov 2024 18:06:58 +0000

Har någon typ av korruptionsproblematik sen 1/10 på lfv produktion :

pg_dump: error: Dumping the contents of table "aim_notam_originalpart" failed: PQgetResult() failed.
pg_dump: error: Error message from server: ERROR:  unexpected chunk size 1408 (expected 1661) in chunk 0 of 1 for toast value 18918695 in pg_toast_18194
pg_dump: error: The command was: COPY aim.aim_notam_originalpart (notam_id, part_num, created_at, e_details, canonical_filing_dtg, canonical_orig_addr, canonical_text) TO stdout;
aimdb_dump: pg_dump failed

1500000 rows

Mvh Pär

---

From: Achilleas Mantzios - cloud <[email-masked]>
Date: Fri, 8 Nov 2024 16:04:07 +0100

On 11/7/24 19:06, Pär Mattsson wrote:
> pg_dump: error: Error message from server: ERROR: unexpected chunk 
> size 1408 (expected 1661) in chunk 0 of 1 for toast value 18918695 in 
> pg_toast_18194
> pg_dump: error: The command was: COPY aim.aim_notam_originalpart 
> (notam_id, part_num, created_at, e_details, canonical_filing_dtg, 
> canonical_orig_addr, canonical_text) TO stdout;
Your DB is corrupted. Either you have valid backup , or you try to 
rectify as is.

In this case, search the net / write a pgplsql func to pinpoint the 
corrupted toast row. Then zero it out.

This could be handy :

CREATE OR REPLACE FUNCTION find_bad_row(text,text,text) RETURNS VOID AS $f$

declare

tblname ALIAS FOR $1;

pkname ALIAS FOR $2;

culprit ALIAS FOR $3;

curid INT := 0;

vcontent TEXT;

badid INT;

begin

FOR badid IN EXECUTE 'SELECT '||pkname||' FROM '||tblname||' ORDER BY 
'||pkname LOOP

curid = curid + 1;

--raise notice 'inspecting row %', curid;

if curid % 100000 = 0 then

raise notice '% rows inspected', curid;

end if;

begin

EXECUTE 'SELECT '||culprit||' FROM '||tblname||' where '||pkname||' = 
'|| badid INTO vcontent;

vcontent := substr(vcontent,1,1000);

exception

when others then

raise notice 'data for table %,  pk=% is corrupt', tblname,badid;

continue;

end;

end loop;

end;

$f$ LANGUAGE plpgsql;