Re: '{"x": 42, "y": null}'::jsonb != '{"x": 42}'::jsonb ... Really?

From: Thomas Kellerer <shammat(at)gmx(dot)net>
To: pgsql-general(at)lists(dot)postgresql(dot)org
Subject: Re: '{"x": 42, "y": null}'::jsonb != '{"x": 42}'::jsonb ... Really?
Date: 2022-06-19 22:30:44
Message-ID: 2ced3259-2cb5-9ecc-3157-69b6cd3f51c8@gmx.net
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Bryn Llewellyn schrieb am 04.06.2022 um 03:41:
> Am I missing a use case where an object with a key-value pair with a
> JSON null value is meaningfully different from one where the key is
> simply absent?
It seems the JSON specification doesn't actually define equality.
But the JSON patch RFC 6902[1] defines the equality of two objects
as:

objects: are considered equal if they contain the same number of
members, and if each member can be considered equal to a member in
the other object, by comparing their keys (as strings) and their
values (using this list of type-specific rules).

As {"x": 42, "y": null} and {"x": 42} do not contain the same number
of members, I think Postgres' behaviour is correct.

Thomas

[1] https://www.rfc-editor.org/rfc/rfc6902#section-4.6

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