Re: Could not open file "pg_subtrans/01EB"

Hi,

I'm trying to investigate a database of one of our clients. The database version is 9.2.5. The client tried to dump one of its databases and then got the next error : 

pg_dump: query returned 2 rows instead of one: SELECT tableoid, oid, (SELECT rolname FROM pg_catalog.pg_roles WHERE oid = datdba) AS dba, pg_encoding_to_char(encoding) AS encoding, datcollate, datctype, datfrozenxid, (SELECT spcname FROM pg_tablespace t WHERE t.oid = dattablespace) AS tablespace, shobj_description(oid, 'pg_database') AS description FROM pg_database WHERE datname = 'db1'

So I tried to query the pg_database and I saw that there are duplicated rows in that table : 

postgres=#  select xmin,xmax,datname,datfrozenxid from pg_database order by datname;

 xmin  |   xmax   |    datname     | datfrozenxid

-------+----------+----------------+--------------

  2351 |        0 | db1            |         1798

  1809 | 21093518 | db1            |         1798

  1806 |        0 | postgres       |         1798

 12594 |        0 | db2            |         1798

  1803 |        0 | template0      |         1798

  1802 |        0 | template1      |         1798

  3590 |        0 |db4  |         1798

  3592 |        0 | db3 |         1798

  1811 | 21077312 | db3 |         1798

(9 rows)

-fsync and full_page_write are set to on.

I changed the databases names but as you can see db1/db3 have duplicated records. I tried to dump the postgresql database and it worked. I run vacuum on the problematic databases : connected to db1/2/3 and run the vacuum command. On many of the object I got the next detail message : 

DETAIL:  x dead row versions cannot be removed yet. I'm the only one working on the database and there are no additional session in pg_stat_activity. So when some of the row versions cannot be removed ?

I tried to reindex the problematic databases but got the next error : 

reindexdb: reindexing of database "db1" failed: ERROR:  could not access status of transaction 32212695

DETAIL:  Could not open file "pg_subtrans/01EB": No such file or directory.

I checked and indeed that file doesn't exist.  

 

I restarted the cluster and I got the same error for every database (in all cases analyze of pg_catalog.pg_shdepend" failed and caused the error) in the log file. 

 

2018-05-06 23:46:54 +08  30185  DETAIL:  Could not open file "pg_subtrans/01EB": No such file or directory.

2018-05-06 23:46:54 +08  30185  CONTEXT:  automatic analyze of table "afa.pg_catalog.pg_shdepend"

2018-05-06 23:47:06 +08  30213  ERROR:  could not access status of transaction 32635595

I generated a new empty subtrans file that will be called 01EB and I restarted my cluster : 

dd if=/dev/zero of=/var/lib/pgsql/data/pg_subtrans/01EB bs=256k count=1

I didnt get any errors in the log of the database.

Afterwards, I still had duplicated values in pg_databases. I tried again to reindex the problematic databases : 

[root@my_host pg_subtrans]# reindexdb db1 -U postgres

Password:

NOTICE:  table "pg_catalog.pg_class" was reindexed

and it is just stuck from that point and didnt advanced to other tables.. In pg_stat_activity I dont see that the state_change is changing.

Any idea how can I further continue ?

Thanks.