Re: Bugreport: incorrect result in 16.1 in query with string_agg(distinct+json_build_object

Oscar van Baten <info(at)oxcro(dot)com> writes:
> We've upgraded one of our instances from 14.10 to 16.1 at AWS
> All fine, except for a certain output which became different.
> At another instance running at 14.7 we are able to reproduce this correct
> answer.
> Removing the `DISTINCT` or replacing `(SELECT a.id)` with `a.id` does solve
> it.
> It looks like a reference issue.

> You can reproduce with the query below.

Hi, I failed to reproduce this. I get the expected output

table_value | string_agg_value | zzz_2
-------------+------------------+------------------------------------------
val_A | val_B | [{"val_1" : "val_A", "val_2" : "val_A"}]
(1 row)

both in HEAD and at 16.1 release (3edc6580c). It seems to me that
either you have some relevant non-default planner setting, or this
is an AWS-specific bug. Could we see the output of
EXPLAIN (VERBOSE, SETTINGS)
for this query on the troublesome system?

We do have an open report of a problem with DISTINCT aggregates,
https://www.postgresql.org/message-id/flat/18264-e363593d7e9feb7d%40postgresql.org
but it's unclear whether this is the same.

regards, tom lane