Re: [GENERAL] Table partionning : INSERT with inconsistent returnligne inserted. - Mailing list pgsql-general

From Vik Fearing
Subject Re: [GENERAL] Table partionning : INSERT with inconsistent returnligne inserted.
Date
Msg-id 9e79b4c4-059b-1500-9d80-6d17a8e5fa16@2ndquadrant.com
Whole thread Raw
In response to [GENERAL] Table partionning : INSERT with inconsistent return ligne inserted.  (STERBECQ Didier <didier.sterbecq@ratp.fr>)
Responses Re: [GENERAL] Table partionning : INSERT with inconsistent returnligne inserted.
List pgsql-general
On 10/18/2017 10:24 AM, STERBECQ Didier wrote:
> Hi,
> 
> I use PostgreSQL 9.6 (9.6.3)  with table partitioning, when I use INSERT
> order psql, it does not show the number of lines inserted.
> 
> I do not see any information in the version notes from the PostgreSQL
> documentation, even with the 9.6.5 update, is it some bug ?

It's not really a bug, but it is quite annoying.

> CREATE FUNCTION t1_part_test_trigger()
> RETURNS TRIGGER AS $$
> BEGIN
>     IF NEW.id >= 1 AND NEW.id <= 1000 THEN
>         INSERT INTO t1_part_01 VALUES (NEW.*);
>     ELSIF NEW.id > 1000 AND NEW.id <= 22000000 THEN
>         INSERT INTO t1_part_02 VALUES (NEW.*);
>     END IF ;
>     RETURN NULL;
> END;
> $$
> LANGUAGE plpgsql;

The problem is here.  You returned null in a BEFORE trigger which
cancels the insert.  As far as PostgreSQL is concerned, you didn't
insert anything into this table (because you didn't) and so it correctly
but annoyingly returns 0.

> hba=> insert into t1_part values (3000001, '3000001' ) ;
> INSERT 0 0                                    -- should be “INSERT 0 1”

To get this effect, which I believe is required for Hibernate and some
other frameworks, you need to create a view with an INSTEAD OF trigger
that inserts into the table, which then get rerouted with your BEFORE
trigger.  Then you insert into the view and get the desired result.
-- 
Vik Fearing                                          +33 6 46 75 15 36
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support


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