Add list of special permitted variables tracking errors - Closes #4591

This list hold tracking errors that in practice are equivalent to
ER_UNKNOWN_SYSTEM_VARIABLE and that we want to handle in the same way.

include/MySQL_Variables.h

@@ -20,6 +20,7 @@ bool update_server_variable(MySQL_Session* session, int idx, int &_rc);
 bool verify_server_variable(MySQL_Session* session, int idx, uint32_t client_hash, uint32_t server_hash);
 bool verify_set_names(MySQL_Session* session);
 bool logbin_update_server_variable(MySQL_Session* session, int idx, int &_rc);
+bool is_perm_track_err(int err, const char* varname);
 
 class MySQL_Variables {
 	static verify_var verifiers[SQL_NAME_LAST_HIGH_WM];

include/proxysql_structs.h

@@ -277,6 +277,11 @@ typedef struct {
 	char * default_value;       // default value
 	bool is_global_variable;	// is it a global variable?
 } mysql_variable_st;
+
+typedef struct {
+	int err;
+	const char* name;
+} var_track_err_st;
 #endif
 
 enum mysql_data_stream_status {
@@ -1218,10 +1223,9 @@ mysql_variable_st mysql_tracked_variables[] {
 	session_track_system_variables
 	session_track_transaction_info
 	*/
-
-
 };
 #else
 extern mysql_variable_st mysql_tracked_variables[];
+extern var_track_err_st perm_track_errs[];
 #endif // PROXYSQL_EXTERN
 #endif // MYSQL_TRACKED_VARIABLES

lib/MySQL_Session.cpp

@@ -2974,6 +2974,8 @@ bool MySQL_Session::handler_again___status_SETTING_GENERIC_VARIABLE(int *_rc, co
 					(myerr == 1193) // variable is not found
 					||
 					(myerr == 1651) // Query cache is disabled
+					||
+					(is_perm_track_err(myerr, var_name)) // Special permitted tracking errors (~= '1193')
 				) {
 					int idx = SQL_NAME_LAST_HIGH_WM;
 					for (int i=0; i<SQL_NAME_LAST_HIGH_WM; i++) {

lib/MySQL_Variables.cpp

@@ -9,6 +9,7 @@
 #endif
 
 #include <sstream>
+#include "mysql/mysqld_error.h"
 
 
 static inline char is_digit(char c) {
@@ -17,6 +18,23 @@ static inline char is_digit(char c) {
 	return 0;
 }
 
+var_track_err_st perm_track_errs[] {
+	// ERROR 1210 (HY000): Variable not supported in combination with Galera:
+	// - Changed by MySQL, previously 'ER_UNKNOWN_SYSTEM_VARIABLE'
+	{ ER_WRONG_ARGUMENTS, "sql_generate_invisible_primary_key" }
+};
+
+bool is_perm_track_err(int err, const char* varname) {
+	const size_t count = sizeof(perm_track_errs) / sizeof(var_track_err_st);
+
+	for (size_t i = 0; i < count; i++) {
+		if (perm_track_errs[i].err == err && (strcasecmp(varname, perm_track_errs[i].name) == 0)) {
+			return true;
+		}
+	}
+	return false;
+}
+
 #include "proxysql_find_charset.h"
 
 verify_var MySQL_Variables::verifiers[SQL_NAME_LAST_HIGH_WM];