Re: Large Scale Aggregation (HashAgg Enhancement) - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: Large Scale Aggregation (HashAgg Enhancement)
Date
Msg-id 1137540562.3180.302.camel@localhost.localdomain
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In response to Re: Large Scale Aggregation (HashAgg Enhancement)  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
On Tue, 2006-01-17 at 21:43 +0000, Simon Riggs wrote:
> OK.... My interest was in expanding the role of HashAgg, which as Rod
> says can be used to avoid the sort, so the overlap between those ideas
> was low anyway.

Am I right in thinking that HashAgg would almost always be quicker than
SortAgg, even for large (> memory) aggregation sets? (Except where the
prior ordering has already been forced via an ORDER BY).

If that is so, then I will probably look to work on this sooner,
especially since we seem to have a clear design.

I'd originally viewed the spill-to-disk logic as a safety measure rather
than as a performance feature.

Best Regards, Simon Riggs



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