Re: Partitions: \d vs \d+

On 29.09.2017 04:33, Amit Langote wrote:

> So, we should be looking at partconstraintdef only when verbose is true,
> because that's only when we set it to a valid value. Now, if
> partconstraintdef is NULL even after verbose is true, that means backend
> returned that there exists no constraint for that partition, which I
> thought would be true for a default partition (because the commit that
> introduced default partitions also introduced "No partition constraint"),
> but it's really not.
>
> For example, \d and \d+ show contradictory outputs for a default partition.
>
> create table p (a int) partition by list (a);
> create table p1 partition of p for values in (1);
> create table pd partition of p default;
>
> \d pd
> Table "public.pd"
> Column | Type | Collation | Nullable | Default
> --------+---------+-----------+----------+---------
> a | integer | | |
> Partition of: p DEFAULT
> No partition constraint
>
> \d+ pd
> Table "public.pd"
> Column | Type | Collation | Nullable | Default | Storage | Stats
> target | Description
> --------+---------+-----------+----------+---------+---------+--------------+-------------
> a | integer | | | | plain | |
> Partition of: p DEFAULT
> Partition constraint: (NOT ((a IS NOT NULL) AND (a = ANY (ARRAY[1]))))
>
>
> Perhaps, there is no case when "No partition constraint" should be output,
> but I may be missing something.

Anyhow, we have to protect ourselves from empty output from
*pg_get_partition_constraintdef*. And printing *No partition constraint*
would be good point to start to examine why we didn't get any constraint
definition.

--
Regards,
Maksim Milyutin