On 2023-Jul-02, Wen Yi wrote:
> Hi community
> When I read the Internals document (41.1. The Query Tree),
> the introduction of the 'the result relation' confuse me.
There are "result relations" in commands that modify a relation, such as
insert or update. The result relation is where the new tuples are
inserted, or where the modified tuples are.
> in my original understand, I guess the use of ResTarget is to store
> the columns of the result, like:
>
> SELECT row_1, row_2 FROM table;
Yeah. Those aren't necessarily in the result relation, because (as the
doc says) a SELECT does not even *have* a result relation.
--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/
"Once again, thank you and all of the developers for your hard work on
PostgreSQL. This is by far the most pleasant management experience of
any database I've worked on." (Dan Harris)
http://archives.postgresql.org/pgsql-performance/2006-04/msg00247.php