Raised when an INSERT, COPY, or UPDATE supplies a value to a column defined as GENERATED ALWAYS (identity or stored generated).
PostgreSQL error 428C9 generated_always appears when you insert or update a column defined as GENERATED ALWAYS. Remove the column from the statement, or switch it to GENERATED BY DEFAULT, to resolve the issue.
PostgreSQL Error 428C9
PostgreSQL raises error code 428C9 with the condition name generated_always when a statement tries to assign a value to a column declared as GENERATED ALWAYS. This category includes identity columns created with GENERATED ALWAYS AS IDENTITY and stored generated columns created with GENERATED ALWAYS AS (expression) STORED.
The server blocks manual writes to these columns to preserve data integrity because their values are supplied automatically by the database engine.
The error surfaces during INSERT, COPY, or UPDATE operations that explicitly reference the protected column.
The failure appears immediately after the query planner detects the prohibited column assignment. Typical touchpoints include application ORM layers, bulk-load scripts, legacy migrations, and ad-hoc SQL run from an editor like Galaxy.
Ignoring the error leaves tables without fresh data, breaks CI pipelines, and can stall deployments.
Correcting the statement or the column definition ensures automated sequences and expressions continue to populate reliable primary keys and derived values.
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Specifying the generated column in the INSERT column list and providing a value forces PostgreSQL to raise 428C9.
Any UPDATE that changes a GENERATED ALWAYS column violates its read-only contract and triggers the error.
Bulk loads that map CSV columns to the generated field result in the same rejection.
Developers sometimes intend GENERATED BY DEFAULT but choose GENERATED ALWAYS, making later data loads fail.
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Yes. Use the OVERRIDING SYSTEM VALUE clause in the INSERT statement to bypass the automatic generation when absolutely necessary.
No. BY DEFAULT columns accept manual values without raising 428C9 unless identity constraints like PRIMARY KEY are violated.
Temporarily switch the column to GENERATED BY DEFAULT or use OVERRIDING SYSTEM VALUE during COPY or INSERT operations.
Galaxy highlights generated columns in the schema panel and its linter warns if you include them in an INSERT, preventing 428C9 before execution.
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