Re: BUG #16733: insert into on conflict(pk) do nothing error violates not-null constraint

On 20/11/2020 07:39, PG Bug reporting form wrote:
> The following bug has been logged on the website:
> 
> Bug reference:      16733
> Logged by:          zhongxuchen
> Email address:      zhongxuchen@gmail.com
> PostgreSQL version: 12.3
> Operating system:   centos8
> Description:
> 
> sorry ,A scene that was missed before！

For the archives: I believe you're referring to 
https://www.postgresql.org/message-id/16706-08837c0cdaf4ce57%40postgresql.org.

> 1、postgresql insert（）values（）on conflict (pk) do update/ do nothing
> 当某个字段在数据库中设置为not null，SQL 错误 [23502]: ERROR: null value in column "name"
> violates not-null constraint
> 
> example：
> CREATE TABLE TEST1 (
> id varchar(100) NOT NULL,
> name varchar(100) NOT NULL,
> status varchar(100) NOT NULL,
> CONSTRAINT test1_pkey PRIMARY KEY (id)
> )
> 
> Initialization data
> insert into TEST1 (ID, NAME,STATUS ) values('4','test','6') ;
> 
> Error scenarios：
> 1、insert into TEST1 as t1 (ID, NAME,STATUS ) values('4',null,'6') on
> conflict
> (id) do update set NAME=COALESCE(excluded.NAME,t1.NAME),
> STATUS=COALESCE(excluded.STATUS,t1.STATUS);
> 
> 2、insert into TEST1 as t1 (ID, NAME,STATUS ) values('4',null,'6') on
> conflict
> (id) do nothing

Both of these fail with an error:

ERROR:  null value in column "name" of relation "test1" violates 
not-null constraint
DETAIL:  Failing row contains (4, null, 6).

This is not a bug. The NOT NULL constraint is checked before checking 
for conflicts.

- Heikki