On Sun, Jul 16, 2023 at 5:48 AM PG Doc comments form <nore...@postgresql.org> wrote:
> The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/15/queries-with.html > Description: > > Hi. > > In the queries WITH documentation > https://www.postgresql.org/docs/15/queries-with.html it is a bit confusing > that MERGE is referenced in several places as being something you can use > inside with, even though it can't. > > If you search for MERGE on the page, you will find the 2 first results is a > reference saying MERGE can be used inside WITH, the same as SELECT, INSERT, > UPDATE, or DELETE. No, they are not, see below. The 3rd result then correctly states that MERGE cannot be > used inside WITH. > > Yes. The first non-intro section says that the following syntax is allowed (you can attach WITH /TO/ MERGE) [ WITH with_query [, ...] ] MERGE INTO [ ONLY ] target_table_name [ * ] [ [ AS ] target_alias ] https://www.postgresql.org/docs/current/sql-merge.html The second section is saying that the "with_query" above cannot contain MERGE, i.e., you cannot put MERGE /IN/ WITH Namely because you cannot attach a RETURNING clause to MERGE. The intro makes it quite clear as well: Specifically, reading the last sentence makes it clear: Each auxiliary statement in a WITH clause can be a SELECT, INSERT, UPDATE, or DELETE; and the WITH clause itself is attached to a primary statement that can be a SELECT, INSERT, UPDATE, DELETE, or MERGE. Here the inside is called the auxiliary while the outside is called primary. David J.
