Re: Fix up grouping sets reorder - Mailing list pgsql-hackers

From Andres Freund
Subject Re: Fix up grouping sets reorder
Date
Msg-id 20190617173324.3nmv4ln6gtkxvkna@alap3.anarazel.de
Whole thread Raw
In response to Fix up grouping sets reorder  (Richard Guo <riguo@pivotal.io>)
Responses Re: Fix up grouping sets reorder  (Andrew Gierth <andrew@tao11.riddles.org.uk>)
List pgsql-hackers
Hi,

On 2019-06-17 17:23:11 +0800, Richard Guo wrote:
> During the reorder of grouping sets into correct prefix order, if only
> one aggregation pass is needed, we follow the order of the ORDER BY
> clause to the extent possible, to minimize the chance that we add
> unnecessary sorts. This is implemented in preprocess_grouping_sets -->
> reorder_grouping_sets.

Thanks for finding!

Andrew, could you take a look at that?

- Andres



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