Re: table partition and column default

On Wed, Dec 25, 2019 at 1:56 PM Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
>
> Fujii-san,
>
> On Wed, Dec 25, 2019 at 12:19 PM Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> >
> > Hi,
> >
> > As the document explains, column defaults can be specified separately for
> > each partition. But I found that INSERT via the partitioned table ignores
> > that default. Is this expected behavior or bug?
> >
> > CREATE TABLE test (i INT, j INT) PARTITION BY RANGE (i);
> > CREATE TABLE test1 PARTITION OF test (j DEFAULT 99) FOR VALUES FROM (1) TO (10);
> > INSERT INTO test VALUES (1, DEFAULT);
> > INSERT INTO test1 VALUES (2, DEFAULT);
> > SELECT * FROM test;
> > i | j
> > ---+--------
> > 1 | (null)
> > 2 | 99
> > (2 rows)
> >
> > In the above example, INSERT accessing directly to the partition uses
> > the default, but INSERT via the partitioned table not.
>
> This is as of now expected.
>
> IIRC, there was some discussion about implementing a feature whereby
> partition's default will used for an attribute if it's null even after
> considering the parent table's default, that is, when no default value
> is defined in the parent. The details are at toward the end of this
> thread:
>
> https://www.postgresql.org/message-id/flat/578398af46350effe7111895a4856b87b02e000e.camel%402ndquadrant.com

Thanks for pointing that thread!

As you mentioned in that thread, I also think that this current
behavior (maybe restriction) should be documented.
What about adding the note like "a partition's default value is
not applied when inserting a tuple through a partitioned table."
into the document?

Patch attached.

Regards,

--
Fujii Masao