Re: postgres sometimes returns no data

On 11/12/2015 11:49 AM, db042190 wrote:
> 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.

The client(Pentaho) and server on the same machine, network, or remotely
connected?

What OS and version, on either end if appropriate?

What does the Postgres log show just before and after ""unexpected
eof...could not receive data.." ?

What do the OS system logs show around the time of the error?

What is/are the job(s) doing?



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>
>


--
Adrian Klaver
adrian.klaver@aklaver.com