PostgreSQL raises SQLSTATE HV002 when a foreign data wrapper requests a runtime parameter value during planning; the parameter must be supplied before the query can run.
fdw_dynamic_parameter_value_needed is thrown when a PostgreSQL foreign data wrapper asks for a parameter value that is unavailable during planning, often in prepared or parameterized queries. Bind all parameters or upgrade the FDW so it defers evaluation to solve the problem.
fdw_dynamic_parameter_value_needed
PostgreSQL emits SQLSTATE HV002 with the condition name fdw_dynamic_parameter_value_needed when a foreign data wrapper (FDW) tries to access a parameter value during the planning phase, but the value has not yet been supplied. The planner cannot continue, so execution stops immediately.
The error is common with prepared statements, parameterized functions, or EXPLAIN commands that reference foreign tables.
Because foreign scans are planned on the server hosting the foreign table, any missing parameter prevents the FDW from validating cost and qualification filters.
During planning, PostgreSQL only knows parameter types, not values. A compliant FDW must treat those parameters as extern and postpone fetching the value until execution.
If the FDW calls the executor interface early, Postgres raises fdw_dynamic_parameter_value_needed to protect stability.
From the user perspective, binding placeholders like $1 or :my_param after PREPARE or inside PL/pgSQL may trigger the failure when the plan touches a foreign table. Missing casts or NULL literals can also confuse the FDW into thinking a value is required immediately.
Provide concrete values before the planner runs. Use EXECUTE prepared_name(actual_value) instead of EXPLAIN or EXECUTE with NULL.
For ad-hoc SQL, replace bind variables with literals or SET the parameter using SET LOCAL inside the same session block.
If you maintain the FDW extension, revise your GetForeignPlan or RecheckForeignScan callbacks so they do not call ExecEvalExpr during planning. Upgrading to the latest postgres_fdw version also resolves historic bugs that produced this error.
Scenario 1 - PREPARE/EXECUTE: Call EXECUTE with all parameters supplied.
If you need an execution-time plan, use EXECUTE format('...') instead of PREPARE.
Scenario 2 - Function parameters: Mark function parameters as IMMUTABLE or pass them as constants in dynamic SQL composed inside the function.
Scenario 3 - EXPLAIN on prepared foreign query: Run EXPLAIN EXECUTE with parameter values, or set auto_explain.log_nested_statements = on and execute normally so EXPLAIN happens after binding.
Always bind parameters before execution, keep FDW versions current, and test prepared statements that touch foreign tables in development.
Using Galaxy’s parameter panel, engineers can preview and supply every placeholder, preventing missing values at runtime.
SQLSTATE 42804 (datatype_mismatch) arises when the supplied parameter has the wrong type, while SQLSTATE HV005 (fdw_error) is a generic FDW failure. Both are fixed by correcting data types or upgrading the FDW, not by re-planning.
.
Usually your SQL omitted a parameter, but poorly written FDW code can also force early evaluation. Test with literals to isolate the cause.
No. Statistics do not affect parameter availability. You must supply the parameter or upgrade the FDW.
No server GUC disables this check. Suppressing it would risk crashes during planning.
Galaxy’s editor highlights unbound parameters and prompts for values before running, so the query reaches PostgreSQL with all placeholders filled.
.avif)
.avif){kind=logo}
