SPI_getargcount — return the number of arguments needed by a statement
prepared by SPI_prepare
int SPI_getargcount(SPIPlanPtr plan)
SPI_getargcount returns the number of arguments needed
to execute a statement prepared by SPI_prepare.
SPIPlanPtr plan
prepared statement (returned by SPI_prepare)
The count of expected arguments for the plan.
If the plan is NULL or invalid,
SPI_result is set to SPI_ERROR_ARGUMENT
and -1 is returned.