The FDW returned a tuple with more or fewer columns than the foreign table definition permits.
fdw_invalid_column_number occurs when a PostgreSQL foreign data wrapper (FDW) delivers a row with an invalid column count. Align the foreign table definition with the remote query or recreate the foreign table to resolve the error.
fdw_invalid_column_number
PostgreSQL raises fdw_invalid_column_number (SQLSTATE HV008) when a foreign data wrapper returns a tuple with a column index that does not exist in the target foreign table.
The mismatch usually appears during SELECT, INSERT, or UPDATE on a foreign table whose definition no longer matches the remote data source. Fixing the definition or SQL resolves the error quickly.
PostgreSQL validates each column coming from an FDW callback.
If the attribute number is zero, negative, or greater than the number of defined columns, fdw_invalid_column_number is thrown.
Schema drift on the remote server, manual ALTER FOREIGN TABLE operations, or incorrect column mapping in the FDW code typically trigger the fault.
Begin by comparing the foreign table definition to the remote table or query result. Make them identical in both column order and count.
Use IMPORT FOREIGN SCHEMA or recreate the foreign table when many columns moved.
If using a custom FDW, update the handler code to emit valid attribute numbers. Recompile and reload the extension, then retry the query.
Remote table gained a new column - run ALTER FOREIGN TABLE ... ADD COLUMN or recreate the table.
Remote table lost a column - run ALTER FOREIGN TABLE ...
DROP COLUMN or refresh the definition with IMPORT FOREIGN SCHEMA.
Using SELECT * in postgres_fdw with column list mismatch - rewrite the query to explicit columns in the correct order.
Version-control foreign table definitions and apply them immediately after remote schema migrations.
Use explicit column lists instead of SELECT * in foreign queries.
Schedule jobs that compare pg_foreign_table metadata to remote schemas.
fdw_unable_to_create_reply (HV00B) - occurs when the FDW cannot parse the remote result.
invalid_column_reference (42703) - local column does not exist in a regular table, not FDW related.
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No. It only signals a mismatch between column definitions. Data remains intact on both servers.
Queries against the foreign table will fail until the mismatch is fixed. Update the definition to restore normal operations.
No. Maintenance commands do not affect FDW column mapping. Adjust the schema or FDW code instead.
Galaxy highlights schema drift by surfacing remote metadata next to local foreign tables, allowing quick fixes directly in the editor.
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