Implementation of WL#1824 "Add replication of character set variables in 4.1",

by binlogging some SET ONE_SHOT CHARACTER_SETetc,
which will be enough until we have it more compact and more complete in 5.0. With the present patch,
replication will work ok between 4.1.3 master and slaves, as long as:
- master and slave have the same GLOBAL.COLLATION_SERVER
- COLLATION_DATABASE and CHARACTER_SET_DATABASE are not used
- application does not use the fact that table is created with charset of the USEd db (BUG#2326).
all of which are not too hard to fulfill. 
ONE_SHOT is reserved for internal use of mysqlbinlog|mysql and works only for charsets,
so we give error if used for non-charset vars.
Fix for BUG#3875 "mysqlbinlog produces wrong ouput  if query uses
 variables containing quotes" and BUG#3943 "Queries with non-ASCII literals are not replicated
 properly after SET NAMES".
Detecting that master and slave have different global charsets or server ids.


mysql-test/r/rpl_server_id1.result:
  it's normal to not run as I have added a test to compare server ids of master and slave
  at startup and stop if equal (unless --replicate-same-server-id)
mysql-test/r/rpl_user_variables.result:
  result update (as we now print charset of user var).
mysql-test/r/user_var.result:
  result update
mysql-test/t/rpl_server_id1.test:
  no need to select as slave is not running
mysql-test/t/user_var.test:
  testing if the content of user vars is escaped when mysqlbinlog prints them,
  and if the name is backquoted.
sql/lex.h:
  new keyword ONE_SHOT
sql/log.cc:
  when writing to the binlog, before writing the actual statement, write some SET ONE_SHOT CHARACTER_SET_CLIENT etc
  for the slave to know the charset variables (which are important as they affect the inserted data).
sql/log_event.cc:
  print charset and collation of user var in mysqlbinlog and SHOW BINLOG EVENTS.
  escape the content of the var. Backquote its name.
  Will ask Bar to check that using my_charset_bin for escaping is ok.
sql/set_var.cc:
  understand SET CHARACTER_SET_CLIENT=10 (don't require a string, accept a number).
  Refuse changing of GLOBAL CHARACTER_SET_SERVER/COLLATION_SERVER if binlog or slave,
  as it will make the master or slave make wrong assumptions.
  A function to catch SET ONE_SHOT on non-charset variables (which is forbidden)
sql/set_var.h:
  no_support_one_shot to know if the var supports ONE_SHOT (only charset vars do, soon timezones).
  Accept int arg in SET CHARACTER_SET_etc
sql/slave.cc:
  when I/O slave thread starts, verify that master's and slave charsets match.
  And by the way verify that server ids are different.
  Don't fail if UNIX_TIMESTAMP() can't be done on master (very old master), that's
  not fatal.
sql/sql_class.cc:
  one_shot
sql/sql_class.h:
  one_shot
sql/sql_lex.h:
  one_shot
sql/sql_parse.cc:
  when SET ONE_SHOT is used, verify that it's only used for charset/collation vars;
  otherwise refuse.
sql/sql_yacc.yy:
  ONE_SHOT keyword in SET

11 files changed, 348 insertions, 71 deletions

diff --git a/sql/lex.h b/sql/lex.h
index e5bc537c213..f8ead8a8d2d 100644
--- a/sql/lex.h
+++ b/sql/lex.h
@@ -310,6 +310,7 @@ static SYMBOL symbols[] = {
   { "OFFSET",		SYM(OFFSET_SYM)},
   { "OLD_PASSWORD",	SYM(OLD_PASSWORD)},
   { "ON",		SYM(ON)},
+  { "ONE_SHOT",		SYM(ONE_SHOT_SYM)},
   { "OPEN",		SYM(OPEN_SYM)},
   { "OPTIMIZE",		SYM(OPTIMIZE)},
   { "OPTION",		SYM(OPTION)},
diff --git a/sql/log.cc b/sql/log.cc
index 8df5ea5096b..e7a142230b1 100644
--- a/sql/log.cc
+++ b/sql/log.cc
@@ -1231,6 +1231,40 @@ bool MYSQL_LOG::write(Log_event* event_info)
 
     if (thd)
     {
+#if MYSQL_VERSION_ID < 50000
+      /*
+        To make replication of charsets working in 4.1 we are writing values
+        of charset related variables before every statement in the binlog,
+        if values of those variables differ from global server-wide defaults.
+        We are using SET ONE_SHOT command so that the charset vars get reset
+        to default after the first non-SET statement.
+        In the next 5.0 this won't be needed as we will use the new binlog
+        format to store charset info.
+      */
+      if ((thd->variables.character_set_client->number !=
+           global_system_variables.collation_server->number) ||
+          (thd->variables.character_set_client->number !=
+           thd->variables.collation_connection->number) ||
+          (thd->variables.collation_server->number !=
+           thd->variables.collation_connection->number))
+      {
+	char buf[200];
+        int written= my_snprintf(buf, sizeof(buf)-1,
+                    "SET ONE_SHOT CHARACTER_SET_CLIENT=%lu,\
+COLLATION_CONNECTION=%lu,COLLATION_DATABASE=%lu,COLLATION_SERVER=%lu",
+                             thd->variables.character_set_client->number,
+                             thd->variables.collation_connection->number,
+                             thd->variables.collation_database->number,
+                             thd->variables.collation_server->number);
+	Query_log_event e(thd, buf, written, 0);
+	e.set_log_pos(this);
+	if (e.write(file))
+	  goto err;
+      }
+#endif
+
+      /* Add logging of timezones here */
+
       if (thd->last_insert_id_used)
       {
 	Intvar_log_event e(thd,(uchar) LAST_INSERT_ID_EVENT,
diff --git a/sql/log_event.cc b/sql/log_event.cc
index fd65ec64a76..a76725a95e0 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -2176,7 +2176,7 @@ int Rand_log_event::exec_event(struct st_relay_log_info* rli)
 void User_var_log_event::pack_info(Protocol* protocol)
 {
   char *buf= 0;
-  uint val_offset= 2 + name_len;
+  uint val_offset= 4 + name_len;
   uint event_len= val_offset;
 
   if (is_null)
@@ -2200,16 +2200,21 @@ void User_var_log_event::pack_info(Protocol* protocol)
       event_len= longlong10_to_str(uint8korr(val), buf + val_offset,-10)-buf;
       break;
     case STRING_RESULT:
-      /*
-	This is correct as pack_info is used for SHOW BINLOG command
-	only. But be carefull this is may be incorrect in other cases as
-	string may contain \ and '.
-      */
-      event_len= val_offset + 2 + val_len;
-      buf= my_malloc(event_len, MYF(MY_WME));
-      buf[val_offset]= '\'';
-      memcpy(buf + val_offset + 1, val, val_len);
-      buf[val_offset + val_len + 1]= '\'';
+      /* 15 is for 'COLLATE' and other chars */
+      buf= my_malloc(event_len+val_len*2+1+2*MY_CS_NAME_SIZE+15, MYF(MY_WME));
+      CHARSET_INFO *cs;
+      if (!(cs= get_charset(charset_number, MYF(0))))
+      {
+        strmov(buf+val_offset, "???");
+        event_len+= 3;
+      }
+      else
+      {
+        char *p= strxmov(buf + val_offset, "_", cs->csname, "'", NullS);
+        p+= escape_string_for_mysql(&my_charset_bin, p, val, val_len);
+        p= strxmov(p, "' COLLATE ", cs->name, NullS);
+        event_len= p-buf;
+      }
       break;
     case ROW_RESULT:
     default:
@@ -2218,8 +2223,10 @@ void User_var_log_event::pack_info(Protocol* protocol)
     }
   }
   buf[0]= '@';
-  buf[1+name_len]= '=';
-  memcpy(buf+1, name, name_len);
+  buf[1]= '`';
+  buf[2+name_len]= '`';
+  buf[3+name_len]= '=';
+  memcpy(buf+2, name, name_len);
   protocol->store(buf, event_len, &my_charset_bin);
   my_free(buf, MYF(MY_ALLOW_ZERO_PTR));
 }
@@ -2311,8 +2318,9 @@ void User_var_log_event::print(FILE* file, bool short_form, char* last_db)
     fprintf(file, "\tUser_var\n");
   }
 
-  fprintf(file, "SET @");
+  fprintf(file, "SET @`");
   my_fwrite(file, (byte*) name, (uint) (name_len), MYF(MY_NABP | MY_WME));
+  fprintf(file, "`");
 
   if (is_null)
   {
@@ -2332,7 +2340,36 @@ void User_var_log_event::print(FILE* file, bool short_form, char* last_db)
       fprintf(file, ":=%s;\n", int_buf);
       break;
     case STRING_RESULT:
-      fprintf(file, ":='%s';\n", val);
+    {
+      char *p;
+      if (!(p= (char *)my_alloca(2*val_len+1)))
+        break; // no error, as we are 'void'
+      escape_string_for_mysql(&my_charset_bin, p, val, val_len);
+#if MYSQL_VERSION_ID < 50000
+      /*
+        For proper behaviour when mysqlbinlog|mysql, we need to explicitely
+        specify the variable's collation. It will however cause problems when
+        people want to mysqlbinlog|mysql into another server not supporting the
+        character set. But there's not much to do about this and it's unlikely.
+      */
+      CHARSET_INFO *cs;
+      if (!(cs= get_charset(charset_number, MYF(0))))
+        /*
+          Generate an unusable command (=> syntax error) is probably the best
+          thing we can do here.
+        */
+        fprintf(file, ":=???;\n");
+      else
+        fprintf(file, ":=_%s'%s' COLLATE %s;\n", cs->csname, p, cs->name);
+#else
+      /*
+        In 5.0 we will have some SET CHARACTER_SET_ect automatically printed
+        for all events where it's needed.
+      */
+      fprintf(file, ":='%s';\n", p);
+#endif
+      my_afree(p);
+    }
       break;
     case ROW_RESULT:
     default:
@@ -2353,7 +2390,9 @@ void User_var_log_event::print(FILE* file, bool short_form, char* last_db)
 int User_var_log_event::exec_event(struct st_relay_log_info* rli)
 {
   Item *it= 0;
-  CHARSET_INFO *charset= get_charset(charset_number, MYF(0));
+  CHARSET_INFO *charset;
+  if (!(charset= get_charset(charset_number, MYF(MY_WME))))
+    return 1;
   LEX_STRING user_var_name;
   user_var_name.str= name;
   user_var_name.length= name_len;
diff --git a/sql/set_var.cc b/sql/set_var.cc
index b3b0153652b..7fdc10858dd 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -1708,19 +1708,31 @@ CHARSET_INFO *get_old_charset_by_name(const char *name)
 bool sys_var_collation::check(THD *thd, set_var *var)
 {
   CHARSET_INFO *tmp;
-  char buff[80];
-  String str(buff,sizeof(buff), system_charset_info), *res;
 
-  if (!(res=var->value->val_str(&str)))
+  if (var->value->result_type() == STRING_RESULT)
   {
-    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
-    return 1;
+    char buff[80];
+    String str(buff,sizeof(buff), system_charset_info), *res;
+    if (!(res=var->value->val_str(&str)))
+    {
+      my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
+      return 1;
+    }
+    if (!(tmp=get_charset_by_name(res->c_ptr(),MYF(0))))
+    {
+      my_error(ER_UNKNOWN_COLLATION, MYF(0), res->c_ptr());
+      return 1;
+    }
   }
-
-  if (!(tmp=get_charset_by_name(res->c_ptr(),MYF(0))))
+  else // INT_RESULT
   {
-    my_error(ER_UNKNOWN_COLLATION, MYF(0), res->c_ptr());
-    return 1;
+    if (!(tmp=get_charset(var->value->val_int(),MYF(0))))
+    {
+      char buf[20];
+      int10_to_str(var->value->val_int(), buf, -10);
+      my_error(ER_UNKNOWN_COLLATION, MYF(0), buf);
+      return 1;
+    }
   }
   var->save_result.charset= tmp;	// Save for update
   return 0;
@@ -1730,23 +1742,36 @@ bool sys_var_collation::check(THD *thd, set_var *var)
 bool sys_var_character_set::check(THD *thd, set_var *var)
 {
   CHARSET_INFO *tmp;
-  char buff[80];
-  String str(buff,sizeof(buff), system_charset_info), *res;
 
-  if (!(res=var->value->val_str(&str)))
-  { 
-    if (!nullable)
+  if (var->value->result_type() == STRING_RESULT)
+  {
+    char buff[80];
+    String str(buff,sizeof(buff), system_charset_info), *res;
+    if (!(res=var->value->val_str(&str)))
     {
-      my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
+      if (!nullable)
+      {
+        my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), name, "NULL");
+        return 1;
+      }
+      tmp= NULL;
+    }
+    else if (!(tmp=get_charset_by_csname(res->c_ptr(),MY_CS_PRIMARY,MYF(0))) &&
+             !(tmp=get_old_charset_by_name(res->c_ptr())))
+    {
+      my_error(ER_UNKNOWN_CHARACTER_SET, MYF(0), res->c_ptr());
       return 1;
     }
-    tmp= NULL;
   }
-  else if (!(tmp=get_charset_by_csname(res->c_ptr(),MY_CS_PRIMARY,MYF(0))) &&
-	   !(tmp=get_old_charset_by_name(res->c_ptr())))
+  else // INT_RESULT
   {
-    my_error(ER_UNKNOWN_CHARACTER_SET, MYF(0), res->c_ptr());
-    return 1;
+    if (!(tmp=get_charset(var->value->val_int(),MYF(0))))
+    {
+      char buf[20];
+      int10_to_str(var->value->val_int(), buf, -10);
+      my_error(ER_UNKNOWN_CHARACTER_SET, MYF(0), buf);
+      return 1;
+    }
   }
   var->save_result.charset= tmp;	// Save for update
   return 0;
@@ -1859,6 +1884,20 @@ void sys_var_character_set_server::set_default(THD *thd, enum_var_type type)
  }
 }
 
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+bool sys_var_character_set_server::check(THD *thd, set_var *var)
+{
+  if ((var->type == OPT_GLOBAL) &&
+      (mysql_bin_log.is_open() ||
+       active_mi->slave_running || active_mi->rli.slave_running))
+  {
+    my_printf_error(0, "Binary logging and replication forbid changing \
+the global server character set or collation", MYF(0));
+    return 1;
+  }
+  return sys_var_character_set::check(thd,var);
+}
+#endif
 
 CHARSET_INFO ** sys_var_character_set_database::ci_ptr(THD *thd,
 						       enum_var_type type)
@@ -1952,6 +1991,20 @@ void sys_var_collation_database::set_default(THD *thd, enum_var_type type)
  }
 }
 
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+bool sys_var_collation_server::check(THD *thd, set_var *var)
+{
+  if ((var->type == OPT_GLOBAL) &&
+      (mysql_bin_log.is_open() ||
+       active_mi->slave_running || active_mi->rli.slave_running))
+  {
+    my_printf_error(0, "Binary logging and replication forbid changing \
+the global server character set or collation", MYF(0));
+    return 1;
+  }
+  return sys_var_collation::check(thd,var);
+}
+#endif
 
 bool sys_var_collation_server::update(THD *thd, set_var *var)
 {
@@ -2524,6 +2577,36 @@ int sql_set_variables(THD *thd, List<set_var_base> *var_list)
 }
 
 
+/*
+  Say if all variables set by a SET support the ONE_SHOT keyword (currently,
+  only character set and collation do; later timezones will).
+
+  SYNOPSIS
+
+  not_all_support_one_shot
+    set_var	List of variables to update
+
+  NOTES
+    It has a "not_" because it makes faster tests (no need to "!")
+
+    RETURN VALUE
+    0	all variables of the list support ONE_SHOT
+    1	at least one does not support ONE_SHOT
+*/
+
+bool not_all_support_one_shot(List<set_var_base> *var_list)
+{
+  List_iterator_fast<set_var_base> it(*var_list);
+  set_var_base *var;
+  while ((var= it++))
+  {
+    if (var->no_support_one_shot())
+      return 1;
+  }
+  return 0;
+}
+
+
 /*****************************************************************************
   Functions to handle SET mysql_internal_variable=const_expr
 *****************************************************************************/
diff --git a/sql/set_var.h b/sql/set_var.h
index 699f320bbd9..64bdfdb718b 100644
--- a/sql/set_var.h
+++ b/sql/set_var.h
@@ -49,10 +49,20 @@ public:
   const char *name;
   
   sys_after_update_func after_update;
-  sys_var(const char *name_arg) :name(name_arg),after_update(0)
-  {}
+#if MYSQL_VERSION_ID < 50000
+  bool no_support_one_shot;
+#endif
+  sys_var(const char *name_arg)
+    :name(name_arg), after_update(0)
+#if MYSQL_VERSION_ID < 50000
+    , no_support_one_shot(1)
+#endif
+    {}
   sys_var(const char *name_arg,sys_after_update_func func)
-    :name(name_arg),after_update(func)
+    :name(name_arg), after_update(func)
+#if MYSQL_VERSION_ID < 50000
+    , no_support_one_shot(1)
+#endif
   {}
   virtual ~sys_var() {}
   virtual bool check(THD *thd, set_var *var);
@@ -487,12 +497,17 @@ public:
 class sys_var_collation :public sys_var_thd
 {
 public:
-  sys_var_collation(const char *name_arg) :sys_var_thd(name_arg) {}
+  sys_var_collation(const char *name_arg) :sys_var_thd(name_arg)
+    {
+#if MYSQL_VERSION_ID < 50000
+    no_support_one_shot= 0;
+#endif
+    }
   bool check(THD *thd, set_var *var);
 SHOW_TYPE type() { return SHOW_CHAR; }
   bool check_update_type(Item_result type)
   {
-    return type != STRING_RESULT;		/* Only accept strings */
+    return ((type != STRING_RESULT) && (type != INT_RESULT));
   }
   bool check_default(enum_var_type type) { return 0; }
   virtual void set_default(THD *thd, enum_var_type type)= 0;
@@ -502,13 +517,23 @@ class sys_var_character_set :public sys_var_thd
 {
 public:
   bool nullable;
-  sys_var_character_set(const char *name_arg) :sys_var_thd(name_arg) 
-  { nullable= 0; }
+  sys_var_character_set(const char *name_arg) :
+    sys_var_thd(name_arg)
+  {
+    nullable= 0;
+#if MYSQL_VERSION_ID < 50000
+    /*
+      In fact only almost all variables derived from sys_var_character_set
+      support ONE_SHOT; character_set_results doesn't. But that's good enough.
+    */
+    no_support_one_shot= 0;
+#endif
+  }
   bool check(THD *thd, set_var *var);
   SHOW_TYPE type() { return SHOW_CHAR; }
   bool check_update_type(Item_result type)
   {
-    return type != STRING_RESULT;		/* Only accept strings */
+    return ((type != STRING_RESULT) && (type != INT_RESULT));
   }
   bool check_default(enum_var_type type) { return 0; }
   bool update(THD *thd, set_var *var);
@@ -541,6 +566,9 @@ class sys_var_character_set_server :public sys_var_character_set
 public:
   sys_var_character_set_server(const char *name_arg) :
     sys_var_character_set(name_arg) {}
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+  bool check(THD *thd, set_var *var);
+#endif
   void set_default(THD *thd, enum_var_type type);
   CHARSET_INFO **ci_ptr(THD *thd, enum_var_type type);
 };
@@ -576,6 +604,9 @@ class sys_var_collation_server :public sys_var_collation
 {
 public:
   sys_var_collation_server(const char *name_arg) :sys_var_collation(name_arg) {}
+#if defined(HAVE_REPLICATION) && (MYSQL_VERSION_ID < 50000)
+  bool check(THD *thd, set_var *var);
+#endif
   bool update(THD *thd, set_var *var);
   void set_default(THD *thd, enum_var_type type);
   byte *value_ptr(THD *thd, enum_var_type type, LEX_STRING *base);
@@ -689,7 +720,10 @@ public:
   virtual int check(THD *thd)=0;	/* To check privileges etc. */
   virtual int update(THD *thd)=0;	/* To set the value */
   /* light check for PS */
-  virtual   int light_check(THD *thd) { return check(thd); }
+  virtual int light_check(THD *thd) { return check(thd); }
+#if MYSQL_VERSION_ID < 50000
+  virtual bool no_support_one_shot() { return 1; }
+#endif
 };
 
 
@@ -731,6 +765,9 @@ public:
   int check(THD *thd);
   int update(THD *thd);
   int light_check(THD *thd);
+#if MYSQL_VERSION_ID < 50000
+  bool no_support_one_shot() { return var->no_support_one_shot; }
+#endif
 };
 
 
@@ -833,6 +870,7 @@ void set_var_init();
 void set_var_free();
 sys_var *find_sys_var(const char *str, uint length=0);
 int sql_set_variables(THD *thd, List<set_var_base> *var_list);
+bool not_all_support_one_shot(List<set_var_base> *var_list);
 void fix_delay_key_write(THD *thd, enum_var_type type);
 ulong fix_sql_mode(ulong sql_mode);
 extern sys_var_str sys_charset_system;
diff --git a/sql/slave.cc b/sql/slave.cc
index fa17a192b12..f88d828df1d 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -72,7 +72,7 @@ static int safe_sleep(THD* thd, int sec, CHECK_KILLED_FUNC thread_killed,
 static int request_table_dump(MYSQL* mysql, const char* db, const char* table);
 static int create_table_from_dump(THD* thd, MYSQL *mysql, const char* db,
 				  const char* table_name, bool overwrite);
-static int check_master_version_and_clock(MYSQL* mysql, MASTER_INFO* mi);
+static int get_master_version_and_clock(MYSQL* mysql, MASTER_INFO* mi);
 
 
 /*
@@ -1187,38 +1187,75 @@ slaves can't replicate a 5.0 or newer master.";
     break;
   }
 
-  MYSQL_RES *master_clock_res;
-  MYSQL_ROW master_clock_row;
-  time_t slave_clock;
-
-  if (mysql_real_query(mysql, "SELECT UNIX_TIMESTAMP()", 23))
-    errmsg= "\"SELECT UNIX_TIMESTAMP()\" failed on master"; 
-  else if (!(master_clock_res= mysql_store_result(mysql)))
+  /*
+    Compare the master and slave's clock. Do not die if master's clock is
+    unavailable (very old master not supporting UNIX_TIMESTAMP()?).
+  */
+  MYSQL_RES *master_res= 0;
+  MYSQL_ROW master_row;
+  
+  if (!mysql_real_query(mysql, "SELECT UNIX_TIMESTAMP()", 23) &&
+      (master_res= mysql_store_result(mysql)) &&
+      (master_row= mysql_fetch_row(master_res)))
   {
-    errmsg= "Could not read the result of \"SELECT UNIX_TIMESTAMP()\" on \
-master"; 
+    mi->clock_diff_with_master= 
+      (long) (time((time_t*) 0) - strtoul(master_row[0], 0, 10));
   }
-  else 
+  else
   {
-    if (!(master_clock_row= mysql_fetch_row(master_clock_res)))
-      errmsg= "Could not read a row from the result of \"SELECT \
-UNIX_TIMESTAMP()\" on master"; 
-    else
-    {
-      slave_clock= time((time_t*) 0);
-      mi->clock_diff_with_master= (long) (slave_clock -
-                                          strtoul(master_clock_row[0], 0, 10));
-      DBUG_PRINT("info",("slave_clock=%lu, master_clock=%s",
-                         slave_clock, master_clock_row[0]));
-    }
-  mysql_free_result(master_clock_res);
+    mi->clock_diff_with_master= 0; /* The "most sensible" value */
+    sql_print_error("Warning: \"SELECT UNIX_TIMESTAMP()\" failed on master, \
+do not trust column Seconds_Behind_Master of SHOW SLAVE STATUS");
+  }
+  if (master_res)
+    mysql_free_result(master_res);      
+ 
+  /*
+    Check that the master's server id and ours are different. Because if they
+    are equal (which can result from a simple copy of master's datadir to slave,
+    thus copying some my.cnf), replication will work but all events will be
+    skipped.
+    Do not die if SHOW VARIABLES LIKE 'SERVER_ID' fails on master (very old
+    master?).
+    Note: we could have put a @@SERVER_ID in the previous SELECT
+    UNIX_TIMESTAMP() instead, but this would not have worked on 3.23 masters.
+  */
+  if (!mysql_real_query(mysql, "SHOW VARIABLES LIKE 'SERVER_ID'", 31) &&
+      (master_res= mysql_store_result(mysql)))
+  {
+    if ((master_row= mysql_fetch_row(master_res)) &&
+        (::server_id == strtoul(master_row[1], 0, 10)) &&
+        !replicate_same_server_id)
+      errmsg= "The slave I/O thread stops because master and slave have equal \
+MySQL server ids; these ids must be different for replication to work (or \
+the --replicate-same-server-id option must be used on slave but this does \
+not always make sense; please check the manual before using it).";
+    mysql_free_result(master_res);
+  }
+
+  /*
+    Check that the master's global character_set_server and ours are the same.
+    Not fatal if query fails (old master?).
+  */
+  if (!mysql_real_query(mysql, "SELECT @@GLOBAL.COLLATION_SERVER", 32) &&
+      (master_res= mysql_store_result(mysql)))
+  {
+    if ((master_row= mysql_fetch_row(master_res)) &&
+        strcmp(master_row[0], global_system_variables.collation_server->name))
+      errmsg= "The slave I/O thread stops because master and slave have \
+different values for the COLLATION_SERVER global variable. The values must \
+be equal for replication to work";
+    mysql_free_result(master_res);
   }
 
+  /* Add a timezones check here */
+
   if (errmsg)
   {
     sql_print_error(errmsg);
     return 1;
   }
+
   return 0;
 }
 
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 9d368db0229..f2978edc033 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -181,6 +181,7 @@ THD::THD():user_time(0), current_statement(0), is_fatal_error(0),
   current_linfo =  0;
   slave_thread = 0;
   variables.pseudo_thread_id= 0;
+  one_shot_set= 0;
   file_id = 0;
   warn_id= 0;
   db_charset= global_system_variables.collation_database;
diff --git a/sql/sql_class.h b/sql/sql_class.h
index d787dcabd00..676ee1b529f 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -801,7 +801,7 @@ public:
   /* scramble - random string sent to client on handshake */
   char	     scramble[SCRAMBLE_LENGTH+1];
 
-  bool       slave_thread;
+  bool       slave_thread, one_shot_set;
   bool	     locked, some_tables_deleted;
   bool       last_cuted_field;
   bool	     no_errors, password, is_fatal_error;
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index 92ed53cf814..3884c8f2674 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -611,7 +611,7 @@ typedef struct st_lex
   uint fk_delete_opt, fk_update_opt, fk_match_option;
   uint slave_thd_opt;
   uint8 describe;
-  bool drop_if_exists, drop_temporary, local_file;
+  bool drop_if_exists, drop_temporary, local_file, one_shot_set;
   bool in_comment, ignore_space, verbose, no_write_to_binlog;
   bool derived_tables;
   bool safe_to_cache_query;
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 7596e37de93..b6e9bd3dd80 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -2918,14 +2918,31 @@ unsent_create_error:
   }
 
   case SQLCOM_SET_OPTION:
+  {
+    List<set_var_base> *lex_var_list= &lex->var_list;
     if (tables && ((res= check_table_access(thd, SELECT_ACL, tables,0)) ||
 		   (res= open_and_lock_tables(thd,tables))))
       break;
-    if (!(res= sql_set_variables(thd, &lex->var_list)))
+    if (lex->one_shot_set && not_all_support_one_shot(lex_var_list))
+    {
+      my_printf_error(0, "The SET ONE_SHOT syntax is reserved for \
+purposes internal to the MySQL server", MYF(0));
+      res= -1;
+      break;
+    }
+    if (!(res= sql_set_variables(thd, lex_var_list)))
+    {
+      /*
+        If the previous command was a SET ONE_SHOT, we don't want to forget
+        about the ONE_SHOT property of that SET. So we use a |= instead of = .
+      */
+      thd->one_shot_set|= lex->one_shot_set;
       send_ok(thd);
+    }
     if (thd->net.report_error)
       res= -1;
     break;
+  }
 
   case SQLCOM_UNLOCK_TABLES:
     unlock_locked_tables(thd);
@@ -3377,6 +3394,29 @@ unsent_create_error:
     break;
   }
   thd->proc_info="query end";			// QQ
+  if (thd->one_shot_set)
+    {
+      /*
+        If this is a SET, do nothing. This is to allow mysqlbinlog to print
+        many SET commands (in this case we want the charset temp setting to
+        live until the real query). This is also needed so that SET
+        CHARACTER_SET_CLIENT... does not cancel itself immediately.
+      */
+      if (lex->sql_command != SQLCOM_SET_OPTION)
+      {
+        thd->variables.character_set_client=
+          global_system_variables.character_set_client;
+        thd->variables.collation_connection=
+          global_system_variables.collation_connection;
+        thd->variables.collation_database=
+          global_system_variables.collation_database;
+        thd->variables.collation_server=
+          global_system_variables.collation_server;
+        thd->update_charset();
+        /* Add timezone stuff here */
+        thd->one_shot_set= 0;
+      }
+    }
   if (res < 0)
     send_error(thd,thd->killed ? ER_SERVER_SHUTDOWN : 0);
 
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 6a40dc3c23a..04aab392285 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -316,6 +316,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token	NUM
 %token	OFFSET_SYM
 %token	ON
+%token  ONE_SHOT_SYM
 %token	OPEN_SYM
 %token	OPTION
 %token	OPTIONALLY
@@ -5002,6 +5003,7 @@ keyword:
 	| NVARCHAR_SYM		{}
 	| OFFSET_SYM		{}
 	| OLD_PASSWORD		{}
+	| ONE_SHOT_SYM		{}
 	| OPEN_SYM		{}
 	| PACK_KEYS_SYM		{}
 	| PARTIAL		{}
@@ -5088,6 +5090,7 @@ set:
 	  lex->sql_command= SQLCOM_SET_OPTION;
 	  lex->option_type=OPT_SESSION;
 	  lex->var_list.empty();
+          lex->one_shot_set= 0;
 	}
 	option_value_list
 	{}
@@ -5106,6 +5109,7 @@ option_type:
 	| GLOBAL_SYM	{ Lex->option_type= OPT_GLOBAL; }
 	| LOCAL_SYM	{ Lex->option_type= OPT_SESSION; }
 	| SESSION_SYM	{ Lex->option_type= OPT_SESSION; }
+	| ONE_SHOT_SYM	{ Lex->option_type= OPT_SESSION; Lex->one_shot_set= 1; }
 	;
 
 opt_var_type: