Have you come across a situation where you have a very huge table Eg: 100 million rows and you need to update the deltas ?
Y'all probably re-create the whole table to cater such a situation, well now you do not have to fret about it, we have merge command released in Postgres 15.
Example:
create table demo (id serial primary key, val int);
inset into demo (val) select x * 10 from generate_series(1, 10) as x;
create table demo1 as (select id, id * 100 as val
from
generate_series(1, 10, 2) as id) ;
select * from demo order by id;
select * from demo1;
merge
into demo as d
using demo1 as d1
on
d.id = d1.id
when matched then
update
set
val = d1.val
when not matched then
insert
(val)
values (d1.val) ;
select * from demo order by id;
Viola ! Easy peasy now !