11.7. Indexes on Expressions

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/14/indexes-expressional.html
Description:

Regarding the paragraph (_emphasis_ added):

> Index expressions are relatively expensive to maintain, because the
derived expression(s) must be computed for _each row upon insertion and
whenever it is updated_.

Does the "it" in the above refer to the entire row or just the columns used
in the expression? Does updating any column of a row trigger an update to
all indexes with expressions?

Thanks in advance for your time and reply.

Cheers,
Chris Lowder