CODEWITHSUNDEEP
postgresqlerror-handlingmigrationupgradecorruption
rootcause000
rootcause000

Reputation: 13

Encountering Toast Table Corruption and Missing Chunk Number Error During PostgreSQL Data Migration

Version - PostgreSQL 10.21, compiled by Visual C++ build 1800, 64-bit

Platform - Windows

When migrating data from PostgreSQL 10.21 to 14.7, we encountered an issue during the dump process related to table corruption, resulting in the error message 'could not open file "base/16510/37857": No such file or directory.'

ERROR: could not open file "base/16510/37857": No such file or directory

Upon checking the 'relkind' for 'relfilenode', it was determined that the type is toast table. In an attempt to recover the data, we initially tried truncating the toast table, but encountered an error preventing successful truncation. As a workaround, we created a new empty file named "37857" under the directory "base/16510." However, this led to a new error: 'missing chunk number 0 for toast value 15977662 in pg_toast_37722.'

ERROR: missing chunk number 0 for toast value 15977662 in pg_toast_37722

ProdDB=# select count(*) from prrhtab;
 count
--------
 232966
(1 row)

ProdDB=# select * from prrhtab;
ERROR:  could not open file "base/16510/37857": No such file or directory
ProdDB=# select relname, relkind from pg_class where relfilenode=37857;
    relname     | relkind
----------------+---------
 pg_toast_37722 | t
(1 row)

ProdDB=# select * from pg_toast.pg_toast_37722;
ERROR:  could not open file "base/16510/37857": No such file or directory
ProdDB=# select count(*) from pg_toast.pg_toast_37722;
ERROR:  could not open file "base/16510/37857": No such file or directory

ProdDB=# truncate table pg_toast.pg_toast_37722;
ERROR:  "pg_toast_37722" is not a table

ProdDB=# select count(*) from pg_toast.pg_toast_37722;
 count
-------
     0
(1 row)

ProdDB=# select * from prrhtab;
ERROR:  could not read block 2635 in file "base/16510/37857": read only 0 of 8192 bytes
ProdDB=# reindex table prrhtab;
REINDEX
ProdDB=# select * from prrhtab;
ERROR:  missing chunk number 0 for toast value 15977662 in pg_toast_37722

ProdDB=# select count(*) from prrhtab;
 count
--------
 232966
(1 row)


ProdDB=# select * from prrhtab order by id desc limit 1;
    id   
---------
 1177027 
(1 row)

To resolve this issue, we proceeded to remove the corrupted rows one by one, and as a result, the 'missing chunk number' error no longer occurred.

Unfortunately, we do not have a backup from before the table corruption occurred. While we were able to proceed with the migration using the aforementioned approach, we were uncertain if there might be an alternative method to resolve this issue without any data loss. Furthermore, the process of checking rows one by one to resolve the 'missing chunk number' error does not appear to be efficient. Therefore, we would appreciate any suggestions for an optimal solution and what could have been the cause so that similar issues can be avoided in future.

Referred to the following thread, but it appears to be time-consuming when dealing with a higher row count.

Upvotes: 0

Views: 775

Answers (1)

Laurenz Albe
Laurenz Albe

Reputation: 247615

You solved the problem in the correct way.

What might have helped you find the problematic rows:

DO
$$DECLARE
   v_pk bigint;  -- or whatever type your primary key is
   v_t text;
BEGIN
   FOR v_pk IN SELECT id FROM prrhtab LOOP
      BEGIN
         SELECT prrhtab::text INTO v_t FROM prrhtab WHERE id = v_pk;
      EXCEPTION
         WHEN OTHERS THEN
            RAISE NOTICE 'Broken row with id = %', v_pk;  -- or go ahead and delete it
      END;
   END LOOP;
END;$$;

Upvotes: 1

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