On 3/29/2013 11:36 AM, Stefan Manegold wrote:
On Fri, Mar 29, 2013 at 11:02:54AM +0100, Budulinku Dejmihrasku
wrote:
Hi,
i hit a strange problem when using alias for an expression in group
by
i run into this with a complex view containing multiple UNION ALL
queries but after a while everything boiled down to a fairly simple
test case that will always produce the error

    Welcome to mclient, the MonetDB/SQL interactive terminal
    (Feb2013-SP1)
    Database: MonetDB v11.15.3 (Feb2013-SP1), 'mapi:monetdb://
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    sql>CREATE VIEW mmtest_v AS SELECT date'2012-01-01' as period,
    1 as
    quantity;
    operation successful (213.074ms)
    sql>SELECT extract(month from period) as m, count(1) as cnt
    FROM
    mmtest_v GROUP BY m;
    Connection terminated
Could you create a bug report for this?
I can indeed reproduce the segfault --- thanks for reporting and providing this easy test!

Could you indeed please file a bug report including your example to reproduce the problem?

Could you then possibly also attach to the bug report the gdb trace I attach to this email?
It shows the location and cause of the segfault.

done - Bug 3264


I am on Ubuntu 12.04.2 LTS
As the alias in GROUP BY works in other cases i expect this is a
bug -
pls confirm and i will be happy to file it.

BTW it looks like MonetDB has generally issues with selects from
more
complex views - i.e. views based on another view(s).
In such cases the results do not match expectations or there is
even an
error. I can reproduce the problem but i only on quite large set of
data (typically 20+ mil. records) and after some data manipulation
got
involved, so i cannot give a simple test case as above.
Any idea how to pass such problem (when large data-set is involved)
to
the development team?
It would be great if you could provide us --- preferably via bug report(s) --- as much information as possiblet to reproduce the problems, such that we can analyze them. For sharing large data sets (if possible; or data generators, if available), we'll need to find for each individual case a solution that is more suitable than attaching them to a bug report.

Stefan

ok - thanks
hopefully we find time soon enough to prepare+scramble some data set to reproduce the issues i mentioned
we are generally happy with MonetDB and this is the least we can do to help you improve :)
milan


Niels
Thanks in advance
milan

        
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Niels Nes, Centrum Wiskunde & Informatica (CWI)
Science Park 123, 1098 XG Amsterdam, The Netherlands
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