From: Tom Lane <tgl@sss.pgh.pa.us>
To: Lukas Eder <lukas.eder@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: Wrong behaviour of array comparison when arrays contain nulls
Date: Wed, 06 Apr 2022 09:37:52 -0400
Message-ID: <3034594.1649252272@sss.pgh.pa.us> (raw)
In-Reply-To: <CAB4ELO7afJgQfZoQfqfMBA7Zk1AdWRkZ9mUN5jpTZupurQTRsA@mail.gmail.com>
References: <CAB4ELO7afJgQfZoQfqfMBA7Zk1AdWRkZ9mUN5jpTZupurQTRsA@mail.gmail.com>
Lukas Eder <lukas.eder@gmail.com> writes:
> For the following query:
> SELECT array[1, NULL] = array[1, NULL]
> H2 returns NULL whereas PostgreSQL returns TRUE. In my opinion and
> intuition, as well as according to ISO/IEC 9075-2:2016(E) 8.2 <comparison
> predicate> GR 1) b) ii), H2 is right and PostgreSQL is wrong.
If we don't impose a total order on array values, then we cannot build
btree indexes on such columns. So yes, this is a deviation from the
SQL standard, and no we are not going to change it.
As for documentation, section 9.19 says
The comparison operators compare the array contents
element-by-element, using the default B-tree comparison function for
the element data type, and sort based on the first difference.
which implies this behavior but perhaps could be more explicit.
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, lukas.eder@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: Wrong behaviour of array comparison when arrays contain nulls
In-Reply-To: <3034594.1649252272@sss.pgh.pa.us>
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