The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/11/sql-update.html
Description:
What we have in doc:
<q>
[ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]
output_expression: An expression to be computed and returned by the UPDATE
command after each row is updated.
</q>
What we have in the wild (Pg8..11):
* when using field names, expression represents NEW values after update;
* when using sub-selects or joined table references, expression represents
OLD values before update.
POC code:
<code>
create temporary table test(id int primary key, status text not null);
insert into test(id, status) values(1, 'initial');
update test t set status='new'
where id=1
returning id,
status as new_status,
(select status from test where id=t.id) as old_status;
</code>
Thus that "after each row is updated" sentence is rather confusing.
/Alexey
