Re: postgres sometimes returns no data

Hi.  We have a postgres 9.1 query in a pentaho job (table input component
contains the query and is followed by various switches) that runs nightly.
More and more frequently (about half the time now), the query returns no
data (or appears to return no data, see last paragraph) when there is
clearly data to be extracted.  And pentaho continues as if nothing is wrong.
Whenever I simply rerun the component manually, the query returns data and I
am able to complete the job.

I'm looking at what I think is a postgres log around one of the times this
last happened.  And trying to correlate it to the time I see in the pentaho
job's log when this component starts up.

Around that time I just see a bunch of "checkpoints are occurring too
frequently...".  About a minute later and coincidentally around the time the
pentaho job ends, I see "unexpected eof...could not receive data..target
machine actively refused it.".  The reason this last item interests me is
that this component is the last postgres item to run in the job.  And the
next/last component wouldn't run long when there is an empty file created by
the problematic component.  The file is empty whenever this behavior occurs.

I'm torn not knowing if this is a postgres issue or pentaho issue.  The fact
that the pentaho log doesn't show the switches as having "finished
processing" makes me think either pentaho wouldnt execute those switches
when there is no data or pentaho is the problem.  The fact that its
happening more often makes me think the db is somehow involved in the
problem.

I did a reindex and vacuum recently hoping it would alleviate the problem.
Not so.  Any advice would be appreciated.