> Is this freshly inserted data you're having issues with?
>
> If so, I suspect you're running into issues where the data
> has been written in another transaction but that transaction
> has not yet committed. The data is **NOT** visible to other
> transactions until the writing transaction commits.
>
> That's by design. PostgreSQL does not have a "READ
> UNCOMMITTED" mode that would permit data that's been written
> but not yet committed to be seen by other transactions.
>
> If that's what's biting you, you need to adjust your code
> so it only expects to find data in the database that's
> actually been committed (maybe by adding appropriate
> locking/synchronization/queuing), or you need to use the
> same connection for reading and writing the uncommitted
> data.
>
> -- Craig Ringer
>
Thanks for the good Idea! Unfortunately it is old data (already inserted since some days) so this cannot be the
reason...