cannot insert into view “…”

Symptoms

An INSERT targeted a view that is not automatically updatable and has no INSTEAD OF trigger or rule. PostgreSQL raises SQLSTATE 0A000 (feature_not_supported).

• Inserting into a non-updatable view.
• No INSTEAD OF trigger or DO INSTEAD rule defined.
• The HINT suggests how to make it work.

What the server log shows

ERROR:  cannot insert into view "order_summary"
DETAIL:  Views containing GROUP BY are not automatically updatable.
HINT:  To enable inserting into the view, provide an INSTEAD OF INSERT trigger or an unconditional ON INSERT DO INSTEAD rule.

Why PostgreSQL raises this — what the manual says

the CREATE VIEW reference (Updatable Views):

“A more complex view that does not satisfy all these conditions is read-only by default: the system will not allow an INSERT, UPDATE, DELETE, or MERGE on the view.”

PostgreSQL can auto-translate writes only for simple views. A view using aggregation, DISTINCT, GROUP BY, joins, etc. has no unambiguous mapping back to base rows, so without an INSTEAD OF trigger/rule the write is unsupported (0A000).

Common causes

• Writing to a view with GROUP BY/DISTINCT/aggregates/joins.
• No INSTEAD OF trigger or DO INSTEAD rule on the view.
• Assuming all views are writable.

How to fix it

1. Add an INSTEAD OF INSERT trigger that writes to base tables.
2. Define an unconditional ON INSERT DO INSTEAD rule.
3. Insert directly into the underlying base table.

Related & next steps

• SQLSTATE 0A000 — Feature Not Supported (full reference)
• Message: cannot change name of view column
• Glossary: Updatable view

Reference: PostgreSQL 18 — CREATE VIEW.