[check_postgres] POSTGRES_TXN_TIME UNKNOWN: Invalid query returned: mydatabase

[Christian Benke]

Hello!

We're using your check_postgres-script since a few months and are very
pleased with it. 
There's only one issue with the txntime-check - sometimes there are
warnings because the query doesn't return a proper answer:

[2008-09-22 16:05:01] SERVICE ALERT: myhost.mycompany.com;Postgres
Transaction Time;UNKNOWN;SOFT;1;POSTGRES_TXN_TIME UNKNOWN: Invalid
query returned: mydatabase

I can't reproduce the problem unfortunately, so i don't really have an
idea what the cause could be - i hope you have any ideas?
I've upgraded from 1.3.1 to 2.1.2 but the issue appeared again shortly
after the upgrade(most of the time it reports fine however).

Regards
Christian