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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Oscar van Baten <info@oxcro.com>
cc: pgsql-bugs@lists.postgresql.org, David Rowley <dgrowleyml@gmail.com>
Subject: Re: Bugreport: incorrect result in 16.1 in query with
 string_agg(distinct+json_build_object
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Comments: In-reply-to Oscar van Baten <info@oxcro.com>
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Oscar van Baten <info@oxcro.com> writes:
> There you go:

> GroupAggregate  (cost=94.38..128.98 rows=200 width=96)
>   Output: a.id, string_agg(DISTINCT 'val_B'::text, ', '::text),
> (json_agg(json_build_object('val_1', a.id, 'val_2', (SubPlan 1))))::text|

Ah, that gave me the clue I needed (maybe I should have deduced it
from your Subject, but I plead ENOCAFFEINE).  Your query as submitted
doesn't use DISTINCT in the STRING_AGG call, but that's needed to
trigger the bug.  And it is indeed the same bug as #18264: it begins
at the same commit, and David's WIP patch fixes it.

			regards, tom lane