HV090ERRORTier 2 — Caution✅ HIGH confidence

fdw_invalid_string_length_or_buffer_length

Category: Foreign Data Wrapper ErrorVersions: PostgreSQL 9.1+

What this means

A foreign data wrapper encountered an invalid string length or buffer length value, indicating either a length of zero, negative, or exceeding allowed bounds.

Why it happens

1String length of zero passed where a non-empty string is required
2Buffer length value is negative or exceeds maximum
3FDW C code computed an incorrect buffer size for string data

How to reproduce

FDW string or buffer operations during query execution or option processing

trigger — this will ERROR

SELECT * FROM my_foreign_table;  -- FDW buffer sizing error

ERROR: HV090: fdw_invalid_string_length_or_buffer_length

Fix 1: Update the FDW extension

FDW has a string length calculation bug

fix

ALTER EXTENSION my_fdw UPDATE;

Why this works

Installs a corrected version of the FDW with proper buffer length handling

What not to do

✗

Do not pass empty strings to FDW options that require non-empty values

Why it's wrong: Zero-length strings can trigger this error in strict FDW implementations

Sources

📚 Official docs: https://www.postgresql.org/docs/current/fdw-error-handling.html

🔧 Source ref: https://www.postgresql.org/docs/current/errcodes-appendix.html

Confidence assessment

✅ HIGH confidence

Standard FDW error code from official PostgreSQL appendix.