[Pgpool-general] pgpool losing queries

[Daniel Codina]

Thanks for answering Tatsuo,

The test I did was:

1) for loop inserting 50 values to a table.
2) stop one of the servers (in that moment the client in the loop gives the
error I commented)
3) The online backup starts and works perfectly.
4) I look for all the values in the table, and, in fact, there is one
missing value.

I see is not a big problem, and more now that I just lose one insert (not
7)(still if would be preferable not to). As an input, still if maybe you
already know that, I think the problem is the health check. I think that,
this problem occurs when the client is trying to insert a value to pgpool,
and thisone has the two nodes with status 2, but one of them it is already
down,... then the insert is lost. I suppose it is because the health check
is done every second, and my inserts too, so, if my insert arrives before
the health check (that makes pgpool correct the node to status 3) it is
lost.

Maybe would be good if pgpool would send the insert to the nodes still up,
but, if it is difficult, maybe it would be possible to reduce the minium
time of the health checks to something "close to zero".

I hope this feedback could help you to make it yet better this projet.

Anyway, in my particular case, now, is more problematic the "unplug wire"
problem,... wich makes pgpool get crazy (in my case), and stop receiving
queries forever. I discovered the "SYN_SENT" thing, but, reduceing the
number could make some other aplications (like ssh) stop working properly.

Thanks!


2010/2/27 Tatsuo Ishii <ishii at sraoss.co.jp>

> How do you judge your queries "lost"? If an insert query commits *and* you
> do not see the data, that's definitely a serious problem. On the
> contrary if you do not confirm the query gets committed, then it's not
> surprising at all.
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
>
> > I detected that my "lost" queries, are lost in the first stage, not in
> the
> > second. Well, provably they are lost just when the postgreSQL server
> falls,
> > maybe pgpool is not noticeing that inmediatly?
> >
> > The error it gives to me, the client is:
> > psql: server closed the connection unexpectedly
> >     This probably means the server terminated abnormally
> >     before or while processing the request.
> >
> > Sending queries every second, more or less, 7 or 8 of them are lost with
> > that message.
> >
> > Thanks!
>
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