While Postgres docs are great (they usually are), I would love some more backgrond.<p>This looks it takes an entire column and upserts all of its rows into another column, on the same or another table.<p>Is that correct? Is this part of the SQL standard? Is this the same as MERGE in SQL Server and Oracle (which has no counterpart in MySQL)?<p>IIRC upsert in PG is different than in Mysql, MS or Oracle; is that the same here?<p>Are there any good resources for this?