HV004ERRORTier 2 — Caution✅ HIGH confidence

FDW invalid data type

Category: Foreign Data Wrapper ErrorVersions: All Postgres versions (with FDW extension)

What this means

SQLSTATE HV004 is raised when a foreign data wrapper encounters a data type that it cannot handle when reading data from the foreign data source.

1The remote data source returns a data type that the FDW cannot map to a Postgres type
2A column type mismatch between the foreign table definition and the actual remote data

FDW receiving an unsupported data type from the remote source.

trigger — this will ERROR

ERROR: invalid type specification

When the FDW reports an invalid type for a specific column.

fix

ALTER FOREIGN TABLE remote_products ALTER COLUMN price TYPE TEXT;
-- read as TEXT and cast in SQL:
SELECT price::NUMERIC FROM remote_products;

Why this works

Using TEXT or a more flexible type for the foreign table column allows the FDW to transfer the value as a string. Cast to the target type in SQL.

🔧 Source ref: Class HV — Foreign Data Wrapper Error

✅ HIGH confidence

Standard SQLSTATE for FDW type mapping errors. Stable across versions.