Horton

Re: Fix up grouping sets reorder

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Richard Guo <riguo@pivotal.io>, Andrew Gierth <andrew@tao11.riddles.org.uk>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2019-06-17T17:33:24Z
Lists: 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

Commits

  1. Repair logic for reordering grouping sets optimization.