MySQL Bugs: #91993: enhance JSON

Bug #91993	enhance JSON_ARRAYAGG by DISTINCT
Submitted:	13 Aug 2018 10:53	Modified:	21 Nov 2019 13:50
Reporter:	Andrej Thomsen	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: JSON	Severity:	S4 (Feature request)
Version:	8.0.12, 8.0.27	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	distinct, json, JSON_ARRAYAGG

Description:
Some use-cases of mine require JSON-Arrays without duplicates. Since JSON_ARRAYAGG() can't do that, I often have to use some mixture of GROUP_CONCAT(DISTINCT col) with CONCAT() and then cast it as JSON. It would be great to just add "DISTINCT" into that function, like it is possible in GROUP_CONCAT().

How to repeat:
Use JSON_ARRAYAGG() with a column, which does contain non unique values.

Hi Mr. Thomson,

Thank you for your feature request.

I find your idea a good addition to the described function.

Verified as reported.

Hello, does anyone know if this function has already been implemented in mysql?

Bug #105541 marked as duplicate of this one.

I signed up for an oracle account, just so I could comment on this.

It appears that this issue is more than 4 years old and MariaDB has had DISTINCT within JSON_ARRAYAGG for more than 2 years.

Can you please give us an update on whether this feature is actually under serious consideration?

It would help us make an informed decision on the correct DB engine for us.

DISTINCT and ORDER BY clauses, just like GROUP_CONCAT(), would be great!

Looking forward to this feature being implemented

Actually :

SELECT ALL CAST(CONCAT('[', GROUP_CONCAT(DISTINCT REPLACE(name, '"', '\\"') ORDER BY name ASC SEPARATOR '","'), ']') AS JSON) AS names
...

Expected :

SELECT ALL JSON_ARRAYAGG(DISTINCT name ORDER BY name ASC) AS names
...

Please!

Since the last comment is from March, I'll chime in ... yes please!