int SPI_execute_plan(SPIPlanPtr plan, Datum * values, const char * nulls,
                     bool read_only, long count)   SPI_execute_plan executes a plan prepared by
   SPI_prepare.  read_only and
   count have the same interpretation as in
   SPI_execute.
  
      execution plan (returned by SPI_prepare)
     
An array of actual parameter values. Must have same length as the plan's number of arguments.
An array describing which parameters are null. Must have same length as the plan's number of arguments. n indicates a null value (entry in values will be ignored); a space indicates a nonnull value (entry in values is valid).
      If nulls is NULL then
      SPI_execute_plan assumes that no parameters are
      null.
     
true for read-only execution
maximum number of rows to return, or 0 for no limit
   The return value is the same as for SPI_execute,
   with the following additional possible error (negative) results:
   
if plan is NULL or invalid, or count is less than 0
if values is NULL and plan was prepared with some parameters
   SPI_processed and
   SPI_tuptable are set as in
   SPI_execute if successful.