MDEV-26: Global transaction ID.

Change of user interface to be more logical and more in line with expectations
to work similar to old-style replication.

User can now explicitly choose in CHANGE MASTER whether binlog position is
taken into account (master_gtid_pos=current_pos) or not (master_gtid_pos=
slave_pos) when slave connects to master.

@@gtid_pos is replaced by three separate variables @@gtid_slave_pos (can
be set by user, replicated GTIDs only), @@gtid_binlog_pos (read only), and
@@gtid_current_pos (a combination of the two, most recent GTID within each
domain). mysql.rpl_slave_state is renamed to mysql.gtid_slave_pos to match.

This fixes MDEV-4474.

1 files changed, 105 insertions, 3 deletions

diff --git a/sql/sys_vars.h b/sql/sys_vars.h
index 8a92f22f3c2..d68761d91ca 100644
--- a/sql/sys_vars.h
+++ b/sql/sys_vars.h
@@ -2024,12 +2024,114 @@ public:
 
 
 /**
-  Class for @@global.gtid_pos.
+  Class for @@global.gtid_current_pos.
 */
-class Sys_var_gtid_pos: public sys_var
+class Sys_var_gtid_current_pos: public sys_var
 {
 public:
-  Sys_var_gtid_pos(const char *name_arg,
+  Sys_var_gtid_current_pos(const char *name_arg,
+          const char *comment, int flag_args, ptrdiff_t off, size_t size,
+          CMD_LINE getopt)
+    : sys_var(&all_sys_vars, name_arg, comment, flag_args, off, getopt.id,
+              getopt.arg_type, SHOW_CHAR, 0, NULL, VARIABLE_NOT_IN_BINLOG,
+              NULL, NULL, NULL)
+  {
+    option.var_type= GET_STR;
+  }
+  bool do_check(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+  bool session_update(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+  bool global_update(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+  bool check_update_type(Item_result type) {
+    DBUG_ASSERT(false);
+    return false;
+  }
+  void session_save_default(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+  }
+  void global_save_default(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+  }
+  uchar *session_value_ptr(THD *thd, LEX_STRING *base)
+  {
+    DBUG_ASSERT(false);
+    return NULL;
+  }
+  uchar *global_value_ptr(THD *thd, LEX_STRING *base);
+};
+
+
+/**
+  Class for @@global.gtid_binlog_pos.
+*/
+class Sys_var_gtid_binlog_pos: public sys_var
+{
+public:
+  Sys_var_gtid_binlog_pos(const char *name_arg,
+          const char *comment, int flag_args, ptrdiff_t off, size_t size,
+          CMD_LINE getopt)
+    : sys_var(&all_sys_vars, name_arg, comment, flag_args, off, getopt.id,
+              getopt.arg_type, SHOW_CHAR, 0, NULL, VARIABLE_NOT_IN_BINLOG,
+              NULL, NULL, NULL)
+  {
+    option.var_type= GET_STR;
+  }
+  bool do_check(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+  bool session_update(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+  bool global_update(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+  bool check_update_type(Item_result type) {
+    DBUG_ASSERT(false);
+    return false;
+  }
+  void session_save_default(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+  }
+  void global_save_default(THD *thd, set_var *var)
+  {
+    DBUG_ASSERT(false);
+  }
+  uchar *session_value_ptr(THD *thd, LEX_STRING *base)
+  {
+    DBUG_ASSERT(false);
+    return NULL;
+  }
+  uchar *global_value_ptr(THD *thd, LEX_STRING *base);
+};
+
+
+/**
+  Class for @@global.gtid_slave_pos.
+*/
+class Sys_var_gtid_slave_pos: public sys_var
+{
+public:
+  Sys_var_gtid_slave_pos(const char *name_arg,
           const char *comment, int flag_args, ptrdiff_t off, size_t size,
           CMD_LINE getopt)
     : sys_var(&all_sys_vars, name_arg, comment, flag_args, off, getopt.id,