Document COPY FROM WHERE restrictions on generated and system columns

Fujii Masao <masao.fujii@gmail.com>

From: Fujii Masao <masao.fujii@gmail.com>

To: pgsql-docs@lists.postgresql.org

Date: 2026-06-25T16:46:41Z

Lists: pgsql-docs

Attachments

v1-v14-18-0001-doc-Clarify-COPY-FROM-WHERE-expression-restrictio.txt (text/plain)
v1-0001-doc-Clarify-COPY-FROM-WHERE-expression-restrictio.patch (application/octet-stream) patch v1-0001

Hi,

I found that generated columns and system columns cannot be used in
COPY FROM WHERE expressions, but the COPY docs still mentions
only the restriction on subqueries.

So I've created the attached patch which updates the docs to also list
generated columns and system columns as unsupported in COPY FROM WHERE
expressions.

Since generated columns have been rejected in COPY FROM WHERE since
v13, that docs change should be backpatched to all supported branches.
But the system-column restriction was introduced in v19, so that part
does not need to be backpatched.

Thoughts?

Regards,

-- 
Fujii Masao