During the execution state, the server makes an execution call into the UDF.
The execution plan, created in the plan building state, is used in the execution state to compute the result set of the SQL query.
These methods can be called: [_enter_state], _describe_extfn, evaluate_extfn, _open_extfn, _fetch_into_extfn, _fetch_block_extfn, _close_extfn, [_leave_state], and _finish_extfn.
typedef enum a_v4_extfn_state { … EXTFNAPIV4_STATE_EXECUTING, … } a_v4_extfn_state;
If an input TABLE parameter exists, and if a PARTITION BY clause exists in the SQL query, then the server invokes the UDF once per available partition.