MDEV-500: Session variable for server_id

MDEV-26: Global transaction id, partial commit

Change server_id to be a session variable.
User with SUPER can set it to binlog with different server_id.
Implement backward-compatible ::server_id mirror for plugins.

18 files changed, 85 insertions, 61 deletions

diff --git a/sql/event_parse_data.cc b/sql/event_parse_data.cc
index ad812a6aa5d..4316a9f1fb8 100644
--- a/sql/event_parse_data.cc
+++ b/sql/event_parse_data.cc
@@ -574,8 +574,8 @@ void Event_parse_data::check_originator_id(THD *thd)
       status= Event_parse_data::SLAVESIDE_DISABLED;
       status_changed= true;
     }
-    originator = thd->server_id;
+    originator = thd->variables.server_id;
   }
   else
-    originator = server_id;
+    originator = global_system_variables.server_id;
 }
diff --git a/sql/item_func.cc b/sql/item_func.cc
index aca76eac82a..8b4e5542a1f 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -6857,7 +6857,7 @@ ulonglong uuid_value;
 
 void uuid_short_init()
 {
-  uuid_value= ((((ulonglong) server_id) << 56) + 
+  uuid_value= ((((ulonglong) global_system_variables.server_id) << 56) +
                (((ulonglong) server_start_time) << 24));
 }
 
diff --git a/sql/log.cc b/sql/log.cc
index aca71915ddf..683f4c6ce01 100644
--- a/sql/log.cc
+++ b/sql/log.cc
@@ -686,7 +686,8 @@ bool Log_to_csv_event_handler::
   /* do a write */
   if (table->field[1]->store(user_host, user_host_len, client_cs) ||
       table->field[2]->store((longlong) thread_id, TRUE) ||
-      table->field[3]->store((longlong) server_id, TRUE) ||
+      table->field[3]->store((longlong) global_system_variables.server_id,
+                             TRUE) ||
       table->field[4]->store(command_type, command_type_len, client_cs))
     goto err;
 
@@ -883,7 +884,7 @@ bool Log_to_csv_event_handler::
     table->field[8]->set_notnull();
   }
 
-  if (table->field[9]->store((longlong) server_id, TRUE))
+  if (table->field[9]->store((longlong)global_system_variables.server_id, TRUE))
     goto err;
   table->field[9]->set_notnull();
 
diff --git a/sql/log_event.cc b/sql/log_event.cc
index fb2ddb2b012..fbbd6309f48 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -537,7 +537,7 @@ static char *slave_load_file_stem(char *buf, uint file_id,
   to_unix_path(buf);
 
   buf = strend(buf);
-  buf = int10_to_str(::server_id, buf, 10);
+  buf = int10_to_str(global_system_variables.server_id, buf, 10);
   *buf++ = '-';
   buf = int10_to_str(event_server_id, buf, 10);
   *buf++ = '-';
@@ -573,7 +573,7 @@ static void cleanup_load_tmpdir()
      LOAD DATA.
   */
   p= strmake(prefbuf, STRING_WITH_LEN(PREFIX_SQL_LOAD));
-  p= int10_to_str(::server_id, p, 10);
+  p= int10_to_str(global_system_variables.server_id, p, 10);
   *(p++)= '-';
   *p= 0;
 
@@ -771,7 +771,7 @@ Log_event::Log_event(THD* thd_arg, uint16 flags_arg, bool using_trans)
    crc(0), thd(thd_arg),
    checksum_alg(BINLOG_CHECKSUM_ALG_UNDEF)
 {
-  server_id=	thd->server_id;
+  server_id=	thd->variables.server_id;
   when=         thd->start_time;
   when_sec_part=thd->start_time_sec_part;
 
@@ -796,7 +796,7 @@ Log_event::Log_event()
    cache_type(Log_event::EVENT_INVALID_CACHE), crc(0),
    thd(0), checksum_alg(BINLOG_CHECKSUM_ALG_UNDEF)
 {
-  server_id=	::server_id;
+  server_id=	global_system_variables.server_id;
   /*
     We can't call my_time() here as this would cause a call before
     my_init() is called
@@ -928,10 +928,11 @@ Log_event::do_shall_skip(Relay_log_info *rli)
   DBUG_PRINT("info", ("ev->server_id: %lu, ::server_id: %lu,"
                       " rli->replicate_same_server_id: %d,"
                       " rli->slave_skip_counter: %lu",
-                      (ulong) server_id, (ulong) ::server_id,
+                      (ulong) server_id, (ulong) global_system_variables.server_id,
                       rli->replicate_same_server_id,
                       rli->slave_skip_counter));
-  if ((server_id == ::server_id && !rli->replicate_same_server_id) ||
+  if ((server_id == global_system_variables.server_id &&
+       !rli->replicate_same_server_id) ||
       (rli->slave_skip_counter == 1 && rli->is_in_group()) ||
       (flags & LOG_EVENT_SKIP_REPLICATION_F &&
        opt_replicate_events_marked_for_skip != RPL_SKIP_REPLICATE))
@@ -4818,7 +4819,7 @@ int Format_description_log_event::do_apply_event(Relay_log_info const *rli)
     perform, we don't call Start_log_event_v3::do_apply_event()
     (this was just to update the log's description event).
   */
-  if (server_id != (uint32) ::server_id)
+  if (server_id != (uint32) global_system_variables.server_id)
   {
     /*
       If the event was not requested by the slave i.e. the master sent
@@ -4844,7 +4845,7 @@ int Format_description_log_event::do_apply_event(Relay_log_info const *rli)
 
 int Format_description_log_event::do_update_pos(Relay_log_info *rli)
 {
-  if (server_id == (uint32) ::server_id)
+  if (server_id == (uint32) global_system_variables.server_id)
   {
     /*
       We only increase the relay log position if we are skipping
@@ -5889,7 +5890,7 @@ int Rotate_log_event::do_update_pos(Relay_log_info *rli)
 #endif
 
   DBUG_PRINT("info", ("server_id=%lu; ::server_id=%lu",
-                      (ulong) this->server_id, (ulong) ::server_id));
+                      (ulong) this->server_id, (ulong) global_system_variables.server_id));
   DBUG_PRINT("info", ("new_log_ident: %s", this->new_log_ident));
   DBUG_PRINT("info", ("pos: %s", llstr(this->pos, buf)));
 
@@ -5909,7 +5910,8 @@ int Rotate_log_event::do_update_pos(Relay_log_info *rli)
     5.0.0, there also are some rotates from the slave itself, in the
     relay log, which shall not change the group positions.
   */
-  if ((server_id != ::server_id || rli->replicate_same_server_id) &&
+  if ((server_id != global_system_variables.server_id ||
+       rli->replicate_same_server_id) &&
       !is_relay_log_event() &&
       !rli->is_in_group())
   {
diff --git a/sql/log_event.h b/sql/log_event.h
index 210b175db3a..be809970c6d 100644
--- a/sql/log_event.h
+++ b/sql/log_event.h
@@ -2426,7 +2426,7 @@ protected:
       Events from ourself should be skipped, but they should not
       decrease the slave skip counter.
      */
-    if (this->server_id == ::server_id)
+    if (this->server_id == global_system_variables.server_id)
       return Log_event::EVENT_SKIP_IGNORE;
     else
       return Log_event::EVENT_SKIP_NOT;
@@ -2817,7 +2817,7 @@ private:
       Events from ourself should be skipped, but they should not
       decrease the slave skip counter.
      */
-    if (this->server_id == ::server_id)
+    if (this->server_id == global_system_variables.server_id)
       return Log_event::EVENT_SKIP_IGNORE;
     else
       return Log_event::EVENT_SKIP_NOT;
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index 6532ecb8733..548230ea48d 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -4937,9 +4937,9 @@ int mysqld_main(int argc, char **argv)
       set_user(mysqld_user, user_info);
   }
 
-  if (opt_bin_log && !server_id)
+  if (opt_bin_log && !global_system_variables.server_id)
   {
-    server_id= 1;
+    global_system_variables.server_id= ::server_id= 1;
 #ifdef EXTRA_DEBUG
     sql_print_warning("You have enabled the binary log, but you haven't set "
                       "server-id to a non-zero value: we force server id to 1; "
@@ -7819,6 +7819,7 @@ mysqld_get_one_option(int optid,
     break;
   case OPT_SERVER_ID:
     server_id_supplied = 1;
+    ::server_id= global_system_variables.server_id;
     break;
   case OPT_ONE_THREAD:
     thread_handling= SCHEDULER_NO_THREADS;
diff --git a/sql/repl_failsafe.cc b/sql/repl_failsafe.cc
index 89fb1bb27de..35b43fd4305 100644
--- a/sql/repl_failsafe.cc
+++ b/sql/repl_failsafe.cc
@@ -89,14 +89,15 @@ void change_rpl_status(ulong from_status, ulong to_status)
 
 void unregister_slave(THD* thd, bool only_mine, bool need_mutex)
 {
-  if (thd->server_id)
+  uint32 thd_server_id= thd->variables.server_id;
+  if (thd_server_id)
   {
     if (need_mutex)
       mysql_mutex_lock(&LOCK_slave_list);
 
     SLAVE_INFO* old_si;
     if ((old_si = (SLAVE_INFO*)my_hash_search(&slave_list,
-                                              (uchar*)&thd->server_id, 4)) &&
+                                              (uchar*)&thd_server_id, 4)) &&
 	(!only_mine || old_si->thd == thd))
     my_hash_delete(&slave_list, (uchar*)old_si);
 
@@ -127,7 +128,7 @@ int register_slave(THD* thd, uchar* packet, uint packet_length)
   if (!(si = (SLAVE_INFO*)my_malloc(sizeof(SLAVE_INFO), MYF(MY_WME))))
     goto err2;
 
-  thd->server_id= si->server_id= uint4korr(p);
+  thd->variables.server_id= si->server_id= uint4korr(p);
   p+= 4;
   get_object(p,si->host, "Failed to register slave: too long 'report-host'");
   get_object(p,si->user, "Failed to register slave: too long 'report-user'");
@@ -145,7 +146,7 @@ int register_slave(THD* thd, uchar* packet, uint packet_length)
   // si->rpl_recovery_rank= uint4korr(p);
   p += 4;
   if (!(si->master_id= uint4korr(p)))
-    si->master_id= server_id;
+    si->master_id= global_system_variables.server_id;
   si->thd= thd;
 
   mysql_mutex_lock(&LOCK_slave_list);
diff --git a/sql/rpl_handler.cc b/sql/rpl_handler.cc
index 258dae0edb2..b100e8b5185 100644
--- a/sql/rpl_handler.cc
+++ b/sql/rpl_handler.cc
@@ -176,7 +176,7 @@ void delegates_destroy()
   plugins add to thd->lex will be automatically unlocked.
  */
 #define FOREACH_OBSERVER(r, f, thd, args)                               \
-  param.server_id= thd->server_id;                                      \
+  param.server_id= thd->variables.server_id;                            \
   /*
      Use a struct to make sure that they are allocated adjacent, check
      delete_dynamic().
@@ -348,7 +348,7 @@ int Binlog_transmit_delegate::reserve_header(THD *thd, ushort flags,
   ulong hlen;
   Binlog_transmit_param param;
   param.flags= flags;
-  param.server_id= thd->server_id;
+  param.server_id= thd->variables.server_id;
 
   int ret= 0;
   read_lock();
diff --git a/sql/rpl_injector.cc b/sql/rpl_injector.cc
index ec1a96e8a2b..a4b04d2e047 100644
--- a/sql/rpl_injector.cc
+++ b/sql/rpl_injector.cc
@@ -108,7 +108,7 @@ int injector::transaction::use_table(server_id_type sid, table tbl)
   if ((error= check_state(TABLE_STATE)))
     DBUG_RETURN(error);
 
-  server_id_type save_id= m_thd->server_id;
+  server_id_type save_id= m_thd->variables.server_id;
   m_thd->set_server_id(sid);
   error= m_thd->binlog_write_table_map(tbl.get_table(),
                                        tbl.is_transactional());
@@ -127,7 +127,7 @@ int injector::transaction::write_row (server_id_type sid, table tbl,
    if (error)
      DBUG_RETURN(error);
 
-   server_id_type save_id= m_thd->server_id;
+   server_id_type save_id= m_thd->variables.server_id;
    m_thd->set_server_id(sid);
    error= m_thd->binlog_write_row(tbl.get_table(), tbl.is_transactional(), 
                                   cols, colcnt, record);
@@ -146,7 +146,7 @@ int injector::transaction::delete_row(server_id_type sid, table tbl,
    if (error)
      DBUG_RETURN(error);
 
-   server_id_type save_id= m_thd->server_id;
+   server_id_type save_id= m_thd->variables.server_id;
    m_thd->set_server_id(sid);
    error= m_thd->binlog_delete_row(tbl.get_table(), tbl.is_transactional(), 
                                    cols, colcnt, record);
@@ -165,7 +165,7 @@ int injector::transaction::update_row(server_id_type sid, table tbl,
    if (error)
      DBUG_RETURN(error);
 
-   server_id_type save_id= m_thd->server_id;
+   server_id_type save_id= m_thd->variables.server_id;
    m_thd->set_server_id(sid);
    error= m_thd->binlog_update_row(tbl.get_table(), tbl.is_transactional(),
                                    cols, colcnt, before, after);
diff --git a/sql/rpl_mi.cc b/sql/rpl_mi.cc
index 65366becc41..ae9927c1204 100644
--- a/sql/rpl_mi.cc
+++ b/sql/rpl_mi.cc
@@ -61,7 +61,9 @@ Master_info::Master_info(LEX_STRING *connection_name_arg,
     my_casedn_str(system_charset_info, cmp_connection_name.str);
   }
 
-  my_init_dynamic_array(&ignore_server_ids, sizeof(::server_id), 16, 16, MYF(0));
+  my_init_dynamic_array(&ignore_server_ids,
+                        sizeof(global_system_variables.server_id), 16, 16,
+                        MYF(0));
   bzero((char*) &file, sizeof(file));
   mysql_mutex_init(key_master_info_run_lock, &run_lock, MY_MUTEX_INIT_FAST);
   mysql_mutex_init(key_master_info_data_lock, &data_lock, MY_MUTEX_INIT_FAST);
@@ -510,7 +512,7 @@ int flush_master_info(Master_info* mi,
   char* ignore_server_ids_buf;
   {
     ignore_server_ids_buf=
-      (char *) my_malloc((sizeof(::server_id) * 3 + 1) *
+      (char *) my_malloc((sizeof(global_system_variables.server_id) * 3 + 1) *
                          (1 + mi->ignore_server_ids.elements), MYF(MY_WME));
     if (!ignore_server_ids_buf)
       DBUG_RETURN(1);
diff --git a/sql/rpl_rli.cc b/sql/rpl_rli.cc
index d5cd6a3efed..5fd52599d9c 100644
--- a/sql/rpl_rli.cc
+++ b/sql/rpl_rli.cc
@@ -1091,7 +1091,8 @@ bool Relay_log_info::is_until_satisfied(THD *thd, Log_event *ev)
 
   if (until_condition == UNTIL_MASTER_POS)
   {
-    if (ev && ev->server_id == (uint32) ::server_id && !replicate_same_server_id)
+    if (ev && ev->server_id == (uint32) global_system_variables.server_id &&
+        !replicate_same_server_id)
       DBUG_RETURN(FALSE);
     log_name= group_master_log_name;
     log_pos= (!ev)? group_master_log_pos :
diff --git a/sql/slave.cc b/sql/slave.cc
index da10169d97b..1c30a8a8b98 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -706,7 +706,7 @@ int start_slave_thread(
 
   if (start_lock)
     mysql_mutex_lock(start_lock);
-  if (!server_id)
+  if (!global_system_variables.server_id)
   {
     if (start_cond)
       mysql_cond_broadcast(start_cond);
@@ -1403,7 +1403,8 @@ static int get_master_version_and_clock(MYSQL* mysql, Master_info* mi)
       (master_res= mysql_store_result(mysql)) &&
       (master_row= mysql_fetch_row(master_res)))
   {
-    if ((::server_id == (mi->master_id= strtoul(master_row[1], 0, 10))) &&
+    if ((global_system_variables.server_id ==
+             (mi->master_id= strtoul(master_row[1], 0, 10))) &&
         !mi->rli.replicate_same_server_id)
     {
       errmsg= "The slave I/O thread stops because master and slave have equal \
@@ -1976,7 +1977,7 @@ int register_slave_on_master(MYSQL* mysql, Master_info *mi,
     DBUG_RETURN(0);
   }
 
-  int4store(pos, server_id); pos+= 4;
+  int4store(pos, global_system_variables.server_id); pos+= 4;
   pos= net_store_data(pos, (uchar*) report_host, report_host_len);
   pos= net_store_data(pos, (uchar*) report_user, report_user_len);
   pos= net_store_data(pos, (uchar*) report_password, report_password_len);
@@ -2529,7 +2530,7 @@ static int request_dump(THD *thd, MYSQL* mysql, Master_info* mi,
   // TODO if big log files: Change next to int8store()
   int4store(buf, (ulong) mi->master_log_pos);
   int2store(buf + 4, binlog_flags);
-  int4store(buf + 6, server_id);
+  int4store(buf + 6, global_system_variables.server_id);
   len = (uint) strlen(logname);
   memcpy(buf + 10, logname,len);
   if (simple_command(mysql, COM_BINLOG_DUMP, buf, len + 10, 1))
@@ -2738,7 +2739,8 @@ int apply_event_and_update_pos(Log_event* ev, THD* thd, Relay_log_info* rli)
     has a Rotate etc).
   */
 
-  thd->server_id = ev->server_id; // use the original server id for logging
+  /* Use the original server id for logging. */
+  thd->variables.server_id = ev->server_id;
   thd->set_time();                            // time the query
   thd->lex->current_select= 0;
   if (!ev->when)
@@ -3947,7 +3949,7 @@ static int process_io_create_file(Master_info* mi, Create_file_log_event* cev)
   }
   DBUG_ASSERT(cev->inited_from_old);
   thd->file_id = cev->file_id = mi->file_id++;
-  thd->server_id = cev->server_id;
+  thd->variables.server_id = cev->server_id;
   cev_not_written = 1;
 
   if (unlikely(net_request_file(net,cev->fname)))
@@ -4620,7 +4622,8 @@ static int queue_event(Master_info* mi,const char* buf, ulong event_len)
 
   mysql_mutex_lock(log_lock);
   s_id= uint4korr(buf + SERVER_ID_OFFSET);
-  if ((s_id == ::server_id && !mi->rli.replicate_same_server_id) ||
+  if ((s_id == global_system_variables.server_id &&
+       !mi->rli.replicate_same_server_id) ||
       /*
         the following conjunction deals with IGNORE_SERVER_IDS, if set
         If the master is on the ignore list, execution of
@@ -4651,7 +4654,8 @@ static int queue_event(Master_info* mi,const char* buf, ulong event_len)
       IGNORE_SERVER_IDS it increments mi->master_log_pos
       as well as rli->group_relay_log_pos.
     */
-    if (!(s_id == ::server_id && !mi->rli.replicate_same_server_id) ||
+    if (!(s_id == global_system_variables.server_id &&
+          !mi->rli.replicate_same_server_id) ||
         (buf[EVENT_TYPE_OFFSET] != FORMAT_DESCRIPTION_EVENT &&
          buf[EVENT_TYPE_OFFSET] != ROTATE_EVENT &&
          buf[EVENT_TYPE_OFFSET] != STOP_EVENT))
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index b3321bd2771..027222e1e82 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -335,7 +335,7 @@ uint create_table_def_key(THD *thd, char *key,
   uint key_length= (uint) (table_end-key);
   if (tmp_table)
   {
-    int4store(key + key_length, thd->server_id);
+    int4store(key + key_length, thd->variables.server_id);
     int4store(key + key_length + 4, thd->variables.pseudo_thread_id);
     key_length+= TMP_TABLE_KEY_EXTRA;
   }
@@ -2782,7 +2782,7 @@ bool open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
 	{
           DBUG_PRINT("error",
                      ("query_id: %lu  server_id: %u  pseudo_thread_id: %lu",
-                      (ulong) table->query_id, (uint) thd->server_id,
+                      (ulong) table->query_id, (uint) thd->variables.server_id,
                       (ulong) thd->variables.pseudo_thread_id));
 	  my_error(ER_CANT_REOPEN_TABLE, MYF(0), table->alias.c_ptr());
 	  DBUG_RETURN(TRUE);
@@ -6100,7 +6100,8 @@ TABLE *open_table_uncached(THD *thd, const char *path, const char *db,
              ("table: '%s'.'%s'  path: '%s'  server_id: %u  "
               "pseudo_thread_id: %lu",
               db, table_name, path,
-              (uint) thd->server_id, (ulong) thd->variables.pseudo_thread_id));
+              (uint) thd->variables.server_id,
+              (ulong) thd->variables.pseudo_thread_id));
 
   table_list.db=         (char*) db;
   table_list.table_name= (char*) table_name;
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 155c6365e76..9b72d728dbd 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -914,7 +914,7 @@ THD::THD()
   /* Variables with default values */
   proc_info="login";
   where= THD::DEFAULT_WHERE;
-  server_id = ::server_id;
+  variables.server_id = global_system_variables.server_id;
   slave_net = 0;
   command=COM_CONNECT;
   *scramble= '\0';
@@ -5157,7 +5157,7 @@ int THD::binlog_write_row(TABLE* table, bool is_trans,
   size_t const len= pack_row(table, cols, row_data, record);
 
   Rows_log_event* const ev=
-    binlog_prepare_pending_rows_event(table, server_id, cols, colcnt,
+    binlog_prepare_pending_rows_event(table, variables.server_id, cols, colcnt,
                                       len, is_trans,
                                       static_cast<Write_rows_log_event*>(0));
 
@@ -5201,7 +5201,7 @@ int THD::binlog_update_row(TABLE* table, bool is_trans,
 #endif
 
   Rows_log_event* const ev=
-    binlog_prepare_pending_rows_event(table, server_id, cols, colcnt,
+    binlog_prepare_pending_rows_event(table, variables.server_id, cols, colcnt,
 				      before_size + after_size, is_trans,
 				      static_cast<Update_rows_log_event*>(0));
 
@@ -5232,7 +5232,7 @@ int THD::binlog_delete_row(TABLE* table, bool is_trans,
   size_t const len= pack_row(table, cols, row_data, record);
 
   Rows_log_event* const ev=
-    binlog_prepare_pending_rows_event(table, server_id, cols, colcnt,
+    binlog_prepare_pending_rows_event(table, variables.server_id, cols, colcnt,
 				      len, is_trans,
 				      static_cast<Delete_rows_log_event*>(0));
 
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 2e1a12cdedb..6196258993e 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -529,6 +529,7 @@ typedef struct system_variables
   ulong tx_isolation;
   ulong updatable_views_with_limit;
   int max_user_connections;
+  ulong server_id;
   /**
     In slave thread we need to know in behalf of which
     thread the query is being run to replicate temp tables properly
@@ -1699,7 +1700,6 @@ public:
     first byte of the packet in do_command()
   */
   enum enum_server_command command;
-  uint32     server_id;
   uint32     file_id;			// for LOAD DATA INFILE
   /* remote (peer) port */
   uint16     peer_port;
@@ -1776,7 +1776,7 @@ public:
                         MY_BITMAP const* cols, size_t colcnt,
                         const uchar *old_data, const uchar *new_data);
 
-  void set_server_id(uint32 sid) { server_id = sid; }
+  void set_server_id(uint32 sid) { variables.server_id = sid; }
 
   /*
     Member functions to handle pending event for row-level logging.
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 0abb249d97b..b1025bc5bcf 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -1257,10 +1257,10 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
       /* TODO: The following has to be changed to an 8 byte integer */
       pos = uint4korr(packet);
       flags = uint2korr(packet + 4);
-      thd->server_id=0; /* avoid suicide */
+      thd->variables.server_id=0; /* avoid suicide */
       if ((slave_server_id= uint4korr(packet+6))) // mysqlbinlog.server_id==0
 	kill_zombie_dump_threads(slave_server_id);
-      thd->server_id = slave_server_id;
+      thd->variables.server_id = slave_server_id;
 
       general_log_print(thd, command, "Log: '%s'  Pos: %ld", packet+10,
                       (long) pos);
diff --git a/sql/sql_repl.cc b/sql/sql_repl.cc
index 5698b4679b6..f6329092ed0 100644
--- a/sql/sql_repl.cc
+++ b/sql/sql_repl.cc
@@ -81,7 +81,7 @@ static int fake_rotate_event(NET* net, String* packet, char* log_file_name,
   uint ident_len = (uint) strlen(p);
   ulong event_len = ident_len + LOG_EVENT_HEADER_LEN + ROTATE_HEADER_LEN +
     (do_checksum ? BINLOG_CHECKSUM_LEN : 0);
-  int4store(header + SERVER_ID_OFFSET, server_id);
+  int4store(header + SERVER_ID_OFFSET, global_system_variables.server_id);
   int4store(header + EVENT_LEN_OFFSET, event_len);
   int2store(header + FLAGS_OFFSET, LOG_EVENT_ARTIFICIAL_F);
 
@@ -539,7 +539,7 @@ static int send_heartbeat_event(NET* net, String* packet,
   uint ident_len = strlen(p);
   ulong event_len = ident_len + LOG_EVENT_HEADER_LEN +
     (do_checksum ? BINLOG_CHECKSUM_LEN : 0);
-  int4store(header + SERVER_ID_OFFSET, server_id);
+  int4store(header + SERVER_ID_OFFSET, global_system_variables.server_id);
   int4store(header + EVENT_LEN_OFFSET, event_len);
   int2store(header + FLAGS_OFFSET, 0);
 
@@ -748,7 +748,7 @@ void mysql_binlog_send(THD* thd, char* log_ident, my_off_t pos,
   mariadb_slave_capability= get_mariadb_slave_capability(thd);
   if (global_system_variables.log_warnings > 1)
     sql_print_information("Start binlog_dump to slave_server(%d), pos(%s, %lu)",
-                        thd->server_id, log_ident, (ulong)pos);
+                        thd->variables.server_id, log_ident, (ulong)pos);
   if (RUN_HOOK(binlog_transmit, transmit_start, (thd, flags, log_ident, pos)))
   {
     errmsg= "Failed to run hook 'transmit_start'";
@@ -1127,7 +1127,8 @@ impossible position";
           int ret;
           ulong signal_cnt;
 	  DBUG_PRINT("wait",("waiting for data in binary log"));
-	  if (thd->server_id==0) // for mysqlbinlog (mysqlbinlog.server_id==0)
+          /* For mysqlbinlog (mysqlbinlog.server_id==0). */
+	  if (thd->variables.server_id==0)
 	  {
             mysql_mutex_unlock(log_lock);
 	    goto end;
@@ -1647,7 +1648,7 @@ void kill_zombie_dump_threads(uint32 slave_server_id)
   while ((tmp=it++))
   {
     if (tmp->command == COM_BINLOG_DUMP &&
-       tmp->server_id == slave_server_id)
+       tmp->variables.server_id == slave_server_id)
     {
       mysql_mutex_lock(&tmp->LOCK_thd_data);    // Lock from delete
       break;
@@ -1856,7 +1857,7 @@ bool change_master(THD* thd, Master_info* mi, bool *master_info_added)
   {
     ulong s_id;
     get_dynamic(&lex_mi->repl_ignore_server_ids, (uchar*) &s_id, i);
-    if (s_id == ::server_id && replicate_same_server_id)
+    if (s_id == global_system_variables.server_id && replicate_same_server_id)
     {
       my_error(ER_SLAVE_IGNORE_SERVER_IDS, MYF(0), static_cast<int>(s_id));
       ret= TRUE;
diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
index 0ad7c787782..6ad36f70904 100644
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -1989,17 +1989,27 @@ static Sys_var_charptr Sys_secure_file_priv(
 
 static bool fix_server_id(sys_var *self, THD *thd, enum_var_type type)
 {
-  server_id_supplied = 1;
-  thd->server_id= server_id;
+  if (type == OPT_GLOBAL)
+  {
+    server_id_supplied = 1;
+    thd->variables.server_id= global_system_variables.server_id;
+    /*
+      Historically, server_id was a global variable that is exported to
+      plugins. Now it is a session variable, and lives in the
+      global_system_variables struct, but we still need to export the
+      value for reading to plugins for backwards compatibility reasons.
+    */
+    ::server_id= global_system_variables.server_id;
+  }
   return false;
 }
 static Sys_var_ulong Sys_server_id(
        "server_id",
        "Uniquely identifies the server instance in the community of "
        "replication partners",
-       GLOBAL_VAR(server_id), CMD_LINE(REQUIRED_ARG, OPT_SERVER_ID),
+       SESSION_VAR(server_id), CMD_LINE(REQUIRED_ARG, OPT_SERVER_ID),
        VALID_RANGE(0, UINT_MAX32), DEFAULT(0), BLOCK_SIZE(1), NO_MUTEX_GUARD,
-       NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(fix_server_id));
+       NOT_IN_BINLOG, ON_CHECK(check_has_super), ON_UPDATE(fix_server_id));
 
 static Sys_var_mybool Sys_slave_compressed_protocol(
        "slave_compressed_protocol",