On Mon, Jan 7, 2013 at 8:44 AM, Niels Nes <Niels.Nes@cwi.nl> wrote:

On Mon, Dec 17, 2012 at 04:59:03PM -0600, Percy Wegmann wrote:
> Dear MonetDB Team,
>
> We're starting to exercise our MonetDB installation more heavily now
> and I've run into a strange issue where I get an occasional "COMMIT:
> failed" message.
>
> It seems that the conditions required to produce this are:
>
> - Concurrently inserting into two different tables
> - At the same time, issuing a SELECT COUNT(*) against either of those
> tables
>
> I've logged a bug with more detailed information, including a Java test
> case:
>
> http://bugs.monetdb.org/show_bug.cgi?id=3210
>
> I'm only just starting my investigation, but I suspect that COUNT(*)
> may be the culprit, since other selects like SELECT * don't seem to
> have this problem.
>
> Does this ring any bells? Are there any special optimizations for
> COUNT(*) that bypass the underlying BAT and/or have side effects on
> some shared table somewhere that could be causing a concurrency
> violation?
>
> Thanks,

Percy

We fixed a problem today which looks very similar too yours. Could you
verify if the fixes checked in to the Oct2012 and Feb2013 branches also
solve your problem?

Niels

>
> --
>
> Percy Wegmann
> +1 512 637 8500 ext 148
>

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--
Niels Nes, Centrum Wiskunde & Informatica (CWI)
Science Park 123, 1098 XG Amsterdam, The Netherlands
room L3.14, phone ++31 20 592-4098 sip:4098@sip.cwi.nl
url: http://www.cwi.nl/~niels e-mail: Niels.Nes@cwi.nl

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Percy Wegmann

+1 512 637 8500 ext 148