HV010ERRORTier 2 — Caution✅ HIGH confidencefdw_function_sequence_error
What this means
A foreign data wrapper callback function was called in the wrong sequence, violating the required FDW execution protocol.
Why it happens
- 1FDW implementation calls IterateForeignScan before BeginForeignScan
- 2EndForeignScan called multiple times without a corresponding BeginForeignScan
- 3FDW code does not follow the required callback invocation order
- 4Bug in FDW code that skips or double-calls lifecycle callbacks
How to reproduce
Foreign table scan execution where FDW callbacks are invoked out of order
SELECT * FROM my_foreign_table; -- FDW with buggy callback sequencingFix 1: Update or fix the FDW extension
FDW extension has a callback sequencing bug
ALTER EXTENSION my_fdw UPDATE;Why this works
Replaces the buggy FDW code with a corrected version that respects callback order
What not to do
Do not attempt to work around FDW sequence errors by reordering your SQL
Why it's wrong: The bug is in the FDW C code, not in your SQL; SQL changes will not fix it
Sources
📚 Official docs: https://www.postgresql.org/docs/current/fdw-callbacks.html
🔧 Source ref: https://www.postgresql.org/docs/current/errcodes-appendix.html
Confidence assessment
✅ HIGH confidence
Standard FDW error code from official PostgreSQL appendix.
See also
🔗 Related errors
📄 Reference pages