[GENERAL] upsert and update filtering

Hi



create table dimc1
(
col1 integer not null,
col2 char(10),
primary key (col1)
);



create table dimc2
(
col1 integer not null,
col2 char(10),
primary key (col1)
);

testdb=# select * from dimc1 order by 1;
 col1 |    col2
------+------------
  111 | foo111
  112 | foo112
(2 rows)

testdb=# select * from dimc2 order by 1;
 col1 |    col2
------+------------
  111 | foo111
  112 | foo122
  211 | foo211


In general it is my understanding it gows like this


insert into dimc1  select * from dimc2
on conflict (col1) do update
SET
col2 = EXCLUDED.col2
;


insert into dimc1  select * from dimc2
on conflict (col1) do update
SET
col2 = EXCLUDED.col2 returning *
;



So far so good

But what if in the conflict situation I want to performa the update ONLY if the record is different. The update seems
tohappen no matter what 
In other words is there anyway I can filter the update to happen (based on the sample date) only for 112 since col2 is
different?  



testdb=# select * from dimc1 order by 1;
 col1 |    col2
------+------------
  112 | foo112

testdb=# select * from dimc2 order by 1;
 col1 |    col2
------+------------
  112 | foo122




Thanks
Armand