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Re: another aggregates test case...

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Tue, 08 Jun 2010 11:54:57 -0400
Message-ID: <4C0E67D1.7050408@thefigtrees.net>
To: Andy Seaborne <andy.seaborne@talis.com>
CC: Axel Polleres <axel.polleres@deri.org>, SPARQL Working Group <public-rdf-dawg@w3.org>
On 6/8/2010 11:47 AM, Andy Seaborne wrote:
> On 08/06/2010 3:12 PM, Lee Feigenbaum wrote:
>> On 6/8/2010 10:04 AM, Andy Seaborne wrote:
>>> I don't see why it needs to be an error - with no aggregation GROUP BY
>>> can be considered to be a a partial sort. Cardinality same as without
>>> GROUP BY. This also happens to be a requirement in some apps - results
>>> clustered by key but the same number of rows as without grouping.
>>> Sorting can make it so, but sorting is potentially more expensive.
>> This sounds like a pretty different model of aggregation then we have
>> now. (Actually sounds similar to the model that was proposed on the
>> comments list a few months ago.) If we went this way, why not do this
>> all the time, and just repeat the values for the aggregate calculations?
>> I prefer to keep the existing aggregate model.
>> Lee
> I'm not happy with the error case when GROUP BY is used and no aggregate
> is explicitly mentioned.
> To keep as close to the model as far as it is currently defined, I would
> be happy with the "null aggregation" case (reduced to a table of keys,
> no aggregate column added, keys are projectable).
> Seems useful in developing queries and makes aggregation reasonably
> orthogonal to grouping.
> SELECT * means all the keys (i.e. variables in scope after grouping)

That seems fine to me.


> Andy
Received on Tuesday, 8 June 2010 15:55:34 UTC

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