Hello Sinisa and everybody else, sorry that I contact you directly! But I tried all suggestions and it still doesn't work! The UDF return string has always 256 characters! I've used my_malloc and my_free! Also I allocated the necessary memory in xxx_init()! But it doesn't work! What can I do? Who is the mysql developer who is specialized in UDF programming! It's very important! To change the initid->max_length has no effect. If I set this value on 12 or so, I will furthermore get 256 characters, why? Is it a bug? Thank you for your help and support! Greetings Tom Some code: // init function my_bool IHistogram_init(UDF_INIT *initid, UDF_ARGS *args, char *message){ // Parameter: ID, filepointer, data if (args->arg_count != 3) { strcpy(message,"Usage: ID, filepointer and data field."); return 1; } initid->ptr = (char*) my_malloc (65535 * sizeof(char), MY_ZEROFILL); // Set types args->arg_type[0] = STRING_RESULT; args->arg_type[1] = STRING_RESULT; args->arg_type[2] = STRING_RESULT; return 0; } void IHistogram_deinit(UDF_INIT *initid) { my_free(initid->ptr, MY_ZEROFILL); } char* IHistogram(UDF_INIT *initid, UDF_ARGS *args, char *result, unsigned long length, char *is_null, char *error){ char* res; // Calc histogram, result: histogram-string res = checkIHist(args->args[0], args->args[1], args->args[2], args->lengths[1], args->lengths[2]); // Error occured if (strcmp(res, "ERROR") == 0){ *error = 1; return 0; } else{ initid->ptr = res; return initid->ptr; } } --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php