cannot use column references in default expression

Symptoms

A column DEFAULT expression referenced another column, which PostgreSQL does not support. It raises SQLSTATE 0A000 (feature_not_supported).

• A DEFAULT expression referenced a table column.
• Defaults must be constant-ish, not depend on other columns.
• Use a generated column or trigger instead.

What the server log shows

ERROR:  cannot use column references in default expression

Why PostgreSQL raises this — what the manual says

As Section 5.2 Default Values explains:

The DEFAULT expression referenced another column of the table, which is not permitted because defaults are computed without access to the rest of the row; use a generated column or trigger for cross-column logic.

A column DEFAULT is evaluated before the row’s other values are known, so it cannot reference sibling columns. Such a reference is unsupported and PostgreSQL reports 0A000.

Common causes

• A DEFAULT clause referencing another column.
• Trying to derive one column’s default from another.
• Porting a schema from a database with different default rules.

How to fix it

1. Use a generated column: GENERATED ALWAYS AS (…) STORED.
2. Compute the value in a BEFORE INSERT/UPDATE trigger.
3. Set the value explicitly in the application or query.

Related & next steps

• SQLSTATE 0A000 — Feature Not Supported (full reference)
• Message: cannot alter type of a column used by a view
• Glossary: Generated column

Reference: PostgreSQL 18 Section 5.4 “Default Values”.