Re: could not access status of transaction 0

Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> writes:
> We seem to be getting this error (in german) once in a while on a rather
> complex database:

> FEHLER: konnte auf den Status von Transaktion 0 nicht zugreifen
> DETAIL: kann Datei >>/var/databases/postgres/data/pg_subtrans/57DA<<
> nicht erstellen: Die Datei existiert bereits

> which roughly translates to

> ERROR: could not access status of transaction 0
> DETAIL: could not create file
> /var/databases/postgres/data/pg_subtrans/57DA<<: File exists

I think we've finally identified the reason for this:
http://archives.postgresql.org/pgsql-committers/2006-01/msg00287.php

> It might be interesting to note that we use slony to replicate a few
> tables of this database to multiple slaves and according to our logs it
> always was the slony-user connected to the database that triggered this
> error.

AFAICT Slony is blameless; the triggering condition is a very high
transaction rate (2000 or more transactions between checkpoints)
plus the bad luck to hit a fairly narrow race-condition window.

regards, tom lane