quote from https://www.postgresql.org/docs/current/sql-select.html
The elements of the PARTITION BY list are interpreted in much the same > fashion as elements of a GROUP BY > <https://www.postgresql.org/docs/current/sql-select.html#SQL-GROUPBY> > clause, except that they are always simple expressions and never the name > or number of an output column. > I think "number of an output column" refers to "ordinal number of an output column". -- I recommend David Deutsch's <<The Beginning of Infinity>> Jian
