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List:       postgresql-general
Subject:    Re: DISTINCT *and* ORDER BY in aggregate functions on expressions(!)y
From:       Alban Hertroys <haramrae () gmail ! com>
Date:       2023-02-28 8:10:54
Message-ID: D9BE942C-58B4-48D0-9DA1-2B7514BA4881 () gmail ! com
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> On 28 Feb 2023, at 3:54, Thorsten Glaser <tg@evolvis.org> wrote:

(…)

> > Well, that may be what you want, but it's not what you wrote in
> > the query.  Follow David's advice and do
> […]
> > I'm pretty sure that this will only incur one evaluation of the
> > common subexpression, so even though it's tedious to type it's not
> > inefficient.
> 
> Thanks. But I fear it's not as simple as you wrote. More like:
> 
> jsonb_build_object('opening_times',
> 	jsonb_agg(DISTINCT jsonb_build_object(
> 		'weekday', cot.weekday,
> 		'from_hour', cot.from_hour,
> 		'to_hour', cot.to_hour)
> 	ORDER BY
> 	    jsonb_build_object(
> 		'weekday', cot.weekday,
> 		'from_hour', cot.from_hour,
> 		'to_hour', cot.to_hour)->>'weekday',
> 	    jsonb_build_object(
> 		'weekday', cot.weekday,
> 		'from_hour', cot.from_hour,
> 		'to_hour', cot.to_hour)->>'from_hour',
> 	    jsonb_build_object(
> 		'weekday', cot.weekday,
> 		'from_hour', cot.from_hour,
> 		'to_hour', cot.to_hour)->>'to_hour')
> )
> 
> Isn't that more like it?


Perhaps you can use a lateral cross join to get the result of jsonb_build_object as a \
jsonb value to pass around?


Alban Hertroys
--
If you can't see the forest for the trees,
cut the trees and you'll find there is no forest.


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