- From: Lee Feigenbaum <lee@thefigtrees.net>
- Date: Tue, 08 Jun 2010 11:54:57 -0400
- 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. Lee > > Andy >
Received on Tuesday, 8 June 2010 15:55:34 UTC