Gbase 8C function / stored procedure parameters (II)

• RETURNS NULL ON NULL INPUT | STRICT：RETURNS NULL ON NULL INPUT or STRICT Used to specify if a parameter of the function is NULL, This function always returns NULL. If this parameter is declared , When there is NULL Value parameter, the function will not be executed ; It just returns one automatically NULL result ;
• [EXTERNAL] SECURITY INVOKER： Indicates that the function will execute with the permission of the user who calls it , This parameter can be omitted ,EXTERNAL Is an optional parameter ;
• [EXTERNAL] SECURITY DEFINER： Declare that the function will execute with the privileges of the user who created it EXTERNAL Is an optional parameter ;
• PARALLEL： Indicates whether the function can be pushed down to DN On the implementation .PARALLEL UNSAFE Indicates that the function cannot be pushed down to DN Execute on and enforce the use of sequential execution plans , For default options ;PARALLEL RESTRICTED Indicates that the function can be pushed down to DN On the implementation , But the requirement must be in DN Leader On the implementation ;PARALLEL SAFE Indicates that the function can be pushed down to DN On the implementation , Safe and unrestricted ;
• execution_cost： Used to estimate the execution cost of the function ,execution_cost With cpu_operator_cost In units of , The value range is positive ;
• result_rows： Estimate the number of rows returned by the function , What is used for function return is a set , The value range is positive , The default value is 1000 That's ok ;
• configuration_parameter： Set the specified database session parameter value to the given value , If value yes DEFAULT perhaps RESET, The default settings of the system are used in the new session .OFF Turn off settings , The value range is string ;
• definition： Define the string constant of this function , It can be an internal function name 、 The path of the object file 、SQL Commands or text written in procedural language ;
• obj_file, link_symbol： Apply to C Language functions , character string obj_file Specifies the absolute path of the dynamic library ;link_symbol Specifies the link symbol of the function , That is, the function is in C The name of the function in the code ;
• attribute： Function optional information , Value range ：isStrict（ Equivalent to STRICT perhaps RETURNS NULL ON NULL INPUT）、isCachable（ Equivalent to IMMUTABLE）.