SQL: vers_current_time refactoring [closes #117]

* session sysvars;
* moved value parsing to set variable phase;
* renamed 'temporal_current_timestamp' to 'vers_current_time'.

15 files changed, 391 insertions, 89 deletions

diff --git a/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result b/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result
index a4d7265e06e..5e8bacbc4d0 100644
--- a/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result
+++ b/mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result
@@ -4769,20 +4769,6 @@ NUMERIC_BLOCK_SIZE	1
 ENUM_VALUE_LIST	NULL
 READ_ONLY	YES
 COMMAND_LINE_ARGUMENT	REQUIRED
-VARIABLE_NAME	TEMPORAL_CURRENT_TIMESTAMP
-SESSION_VALUE	NULL
-GLOBAL_VALUE	now
-GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	now
-VARIABLE_SCOPE	GLOBAL
-VARIABLE_TYPE	VARCHAR
-VARIABLE_COMMENT	Default AS OF value for versioned tables
-NUMERIC_MIN_VALUE	NULL
-NUMERIC_MAX_VALUE	NULL
-NUMERIC_BLOCK_SIZE	NULL
-ENUM_VALUE_LIST	NULL
-READ_ONLY	NO
-COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	THREAD_CACHE_SIZE
 SESSION_VALUE	NULL
 GLOBAL_VALUE	151
@@ -5133,12 +5119,26 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	NEVER,COMPLEMENTARY,PREFERABLY
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
+VARIABLE_NAME	VERS_CURRENT_TIME
+SESSION_VALUE	NOW
+GLOBAL_VALUE	NOW
+GLOBAL_VALUE_ORIGIN	COMPILE-TIME
+DEFAULT_VALUE	now
+VARIABLE_SCOPE	SESSION
+VARIABLE_TYPE	VARCHAR
+VARIABLE_COMMENT	Default AS OF value for versioned tables
+NUMERIC_MIN_VALUE	NULL
+NUMERIC_MAX_VALUE	NULL
+NUMERIC_BLOCK_SIZE	NULL
+ENUM_VALUE_LIST	NULL
+READ_ONLY	NO
+COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	VERS_FORCE
-SESSION_VALUE	NULL
+SESSION_VALUE	OFF
 GLOBAL_VALUE	OFF
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
 DEFAULT_VALUE	OFF
-VARIABLE_SCOPE	GLOBAL
+VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	BOOLEAN
 VARIABLE_COMMENT	Force system versioning for all created tables
 NUMERIC_MIN_VALUE	NULL
@@ -5148,11 +5148,11 @@ ENUM_VALUE_LIST	OFF,ON
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	VERS_HIDE
-SESSION_VALUE	NULL
+SESSION_VALUE	AUTO
 GLOBAL_VALUE	AUTO
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
 DEFAULT_VALUE	AUTO
-VARIABLE_SCOPE	GLOBAL
+VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	ENUM
 VARIABLE_COMMENT	Hide system versioning from being displayed in table info. AUTO: hide implicit system fields only in non-versioned and AS OF queries; IMPLICIT: hide implicit system fields in all queries; FULL: hide any system fields in all queries and hide versioning info in SHOW commands; NEVER: don't hide system fields
 NUMERIC_MIN_VALUE	NULL
diff --git a/mysql-test/suite/versioning/r/sysvars.result b/mysql-test/suite/versioning/r/sysvars.result
index 120a3583754..dbab7f2c910 100644
--- a/mysql-test/suite/versioning/r/sysvars.result
+++ b/mysql-test/suite/versioning/r/sysvars.result
@@ -1,27 +1,36 @@
 create table t (a int) with system versioning;
 insert into t values (1);
 update t set a= 2;
+show global variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	NOW
+show variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	NOW
 select * from t;
 a
 2
-show variables where variable_name = "temporal_current_timestamp";
+set vers_current_time = '2031-1-1 0:0:0';
+show variables like 'vers_current_time';
 Variable_name	Value
-temporal_current_timestamp	now
-set global temporal_current_timestamp = '2031-1-1 0:0:0';
+vers_current_time	2031-01-01 00:00:00.000000
 select * from t;
 a
 2
-set global temporal_current_timestamp = '2011-1-1 0:0:0';
+set vers_current_time = '2011-1-1 0:0:0';
+show variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	2011-01-01 00:00:00.000000
 select * from t;
 a
-set global temporal_current_timestamp = 'all';
+set vers_current_time = 'all';
+show variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	ALL
 select * from t;
 a
 2
 1
-show variables where Variable_name like "temporal_current_timestamp%";
-Variable_name	Value
-temporal_current_timestamp	all
 create view vt as select * from t;
 select * from t;
 a
@@ -32,9 +41,62 @@ select * from (select * from t) as tt;
 a
 2
 1
-set session temporal_current_timestamp = 'now';
-ERROR HY000: Variable 'temporal_current_timestamp' is a GLOBAL variable and should be set with SET GLOBAL
-set global temporal_current_timestamp = 'now';
+set global vers_current_time= 'alley';
+ERROR 42000: Variable 'vers_current_time' can't be set to the value of 'alley'
+set global vers_current_time= null;
+ERROR 42000: Variable 'vers_current_time' can't be set to the value of 'NULL'
+set global vers_current_time= 1;
+ERROR 42000: Incorrect argument type to variable 'vers_current_time'
+set global vers_current_time= 1.1;
+ERROR 42000: Incorrect argument type to variable 'vers_current_time'
+set vers_current_time= 'alley';
+ERROR 42000: Variable 'vers_current_time' can't be set to the value of 'alley'
+set vers_current_time= null;
+ERROR 42000: Variable 'vers_current_time' can't be set to the value of 'NULL'
+set vers_current_time= 1;
+ERROR 42000: Incorrect argument type to variable 'vers_current_time'
+set vers_current_time= 1.1;
+ERROR 42000: Incorrect argument type to variable 'vers_current_time'
+set global vers_current_time= '1911-11-11 11:11:11.1111119';
+show global variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1911-11-11 11:11:11.111111
+set global vers_current_time= '1900-01-01 00:00:00';
+show global variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1900-01-01 00:00:00.000000
+set global vers_current_time= timestamp'1911-11-11 11:11:11.1111119';
+Warnings:
+Note	1292	Truncated incorrect datetime value: '1911-11-11 11:11:11.1111119'
+show global variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1911-11-11 11:11:11.111111
+set @ts= timestamp'1900-01-01 00:00:00';
+set global vers_current_time= @ts;
+show global variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1900-01-01 00:00:00.000000
+set vers_current_time= '1911-11-11 11:11:11.1111119';
+show variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1911-11-11 11:11:11.111111
+set vers_current_time= '1900-01-01 00:00:00';
+show variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1900-01-01 00:00:00.000000
+set vers_current_time= timestamp'1911-11-11 11:11:11.1111119';
+Warnings:
+Note	1292	Truncated incorrect datetime value: '1911-11-11 11:11:11.1111119'
+show variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1911-11-11 11:11:11.111111
+set @ts= timestamp'1900-01-01 00:00:00';
+set vers_current_time= @ts;
+show variables like 'vers_current_time';
+Variable_name	Value
+vers_current_time	1900-01-01 00:00:00.000000
+set global vers_current_time= 'now';
+set vers_current_time= 'now';
 show variables where variable_name = "vers_hide";
 Variable_name	Value
 vers_hide	IMPLICIT
@@ -42,7 +104,7 @@ select * from t for system_time all;
 a
 2
 1
-set global vers_hide= AUTO;
+set vers_hide= AUTO;
 select * from t;
 a
 2
@@ -61,11 +123,11 @@ select * from t for system_time timestamp between '0-0-0' and current_timestamp(
 a	sys_trx_start	sys_trx_end
 2	TIMESTAMP	TIMESTAMP
 1	TIMESTAMP	TIMESTAMP
-set global vers_hide= NEVER;
+set vers_hide= NEVER;
 select * from t;
 a	sys_trx_start	sys_trx_end
 2	TIMESTAMP	TIMESTAMP
-set global vers_hide= FULL;
+set vers_hide= FULL;
 create or replace table t (
 x int,
 st timestamp(6) generated always as row start,
@@ -85,4 +147,4 @@ select * from t for system_time all;
 x
 1
 drop table t;
-set global vers_hide= IMPLICIT;
+set vers_hide= IMPLICIT;
diff --git a/mysql-test/suite/versioning/t/sysvars.test b/mysql-test/suite/versioning/t/sysvars.test
index ba985a92c9a..b6deadb8470 100644
--- a/mysql-test/suite/versioning/t/sysvars.test
+++ b/mysql-test/suite/versioning/t/sysvars.test
@@ -2,18 +2,21 @@ create table t (a int) with system versioning;
 insert into t values (1);
 update t set a= 2;
 
+show global variables like 'vers_current_time';
+show variables like 'vers_current_time';
 select * from t;
-show variables where variable_name = "temporal_current_timestamp";
 
-set global temporal_current_timestamp = '2031-1-1 0:0:0';
+set vers_current_time = '2031-1-1 0:0:0';
+show variables like 'vers_current_time';
 select * from t;
 
-set global temporal_current_timestamp = '2011-1-1 0:0:0';
+set vers_current_time = '2011-1-1 0:0:0';
+show variables like 'vers_current_time';
 select * from t;
 
-set global temporal_current_timestamp = 'all';
+set vers_current_time = 'all';
+show variables like 'vers_current_time';
 select * from t;
-show variables where Variable_name like "temporal_current_timestamp%";
 
 create view vt as select * from t;
 select * from t;
@@ -21,15 +24,61 @@ drop view vt;
 
 select * from (select * from t) as tt;
 
---error ER_GLOBAL_VARIABLE
-set session temporal_current_timestamp = 'now';
+# global
+--error ER_WRONG_VALUE_FOR_VAR
+set global vers_current_time= 'alley';
+--error ER_WRONG_VALUE_FOR_VAR
+set global vers_current_time= null;
+--error ER_WRONG_TYPE_FOR_VAR
+set global vers_current_time= 1;
+--error ER_WRONG_TYPE_FOR_VAR
+set global vers_current_time= 1.1;
 
-set global temporal_current_timestamp = 'now';
+# session
+--error ER_WRONG_VALUE_FOR_VAR
+set vers_current_time= 'alley';
+--error ER_WRONG_VALUE_FOR_VAR
+set vers_current_time= null;
+--error ER_WRONG_TYPE_FOR_VAR
+set vers_current_time= 1;
+--error ER_WRONG_TYPE_FOR_VAR
+set vers_current_time= 1.1;
+
+# global
+set global vers_current_time= '1911-11-11 11:11:11.1111119';
+show global variables like 'vers_current_time';
+
+set global vers_current_time= '1900-01-01 00:00:00';
+show global variables like 'vers_current_time';
+
+set global vers_current_time= timestamp'1911-11-11 11:11:11.1111119';
+show global variables like 'vers_current_time';
+
+set @ts= timestamp'1900-01-01 00:00:00';
+set global vers_current_time= @ts;
+show global variables like 'vers_current_time';
+
+# session
+set vers_current_time= '1911-11-11 11:11:11.1111119';
+show variables like 'vers_current_time';
+
+set vers_current_time= '1900-01-01 00:00:00';
+show variables like 'vers_current_time';
+
+set vers_current_time= timestamp'1911-11-11 11:11:11.1111119';
+show variables like 'vers_current_time';
+
+set @ts= timestamp'1900-01-01 00:00:00';
+set vers_current_time= @ts;
+show variables like 'vers_current_time';
+
+set global vers_current_time= 'now';
+set vers_current_time= 'now';
 
 show variables where variable_name = "vers_hide";
 select * from t for system_time all;
 
-set global vers_hide= AUTO;
+set vers_hide= AUTO;
 select * from t;
 select * from t for system_time as of timestamp current_timestamp(6);
 --replace_regex /\d{4}-\d\d-\d\d \d\d:\d\d:\d\d\.\d{6}/TIMESTAMP/
@@ -39,11 +88,11 @@ select * from t for system_time timestamp from '0-0-0' to current_timestamp(6);
 --replace_regex /\d{4}-\d\d-\d\d \d\d:\d\d:\d\d\.\d{6}/TIMESTAMP/
 select * from t for system_time timestamp between '0-0-0' and current_timestamp(6);
 
-set global vers_hide= NEVER;
+set vers_hide= NEVER;
 --replace_regex /\d{4}-\d\d-\d\d \d\d:\d\d:\d\d\.\d{6}/TIMESTAMP/
 select * from t;
 
-set global vers_hide= FULL;
+set vers_hide= FULL;
 create or replace table t (
   x int,
   st timestamp(6) generated always as row start,
@@ -59,4 +108,4 @@ select * from t;
 select * from t for system_time all;
 
 drop table t;
-set global vers_hide= IMPLICIT;
\ No newline at end of file
+set vers_hide= IMPLICIT;
diff --git a/plugin/versioning/versioning.cc b/plugin/versioning/versioning.cc
index c1a5a7cd6a5..016367f89f4 100644
--- a/plugin/versioning/versioning.cc
+++ b/plugin/versioning/versioning.cc
@@ -17,6 +17,7 @@
 #include <mysql_version.h>
 #include <mysqld.h>
 #include "sql_plugin.h"                         // st_plugin_int
+#include "sql_class.h"
 
 /*
   Disable __attribute__() on non-gcc compilers.
@@ -29,16 +30,20 @@ static int forced_versioning_init(void *p __attribute__ ((unused)))
 {
 
   DBUG_ENTER("forced_versioning_init");
-  vers_force= true;
-  vers_hide= VERS_HIDE_FULL;
+  mysql_mutex_lock(&LOCK_global_system_variables);
+  global_system_variables.vers_force= true;
+  global_system_variables.vers_hide= VERS_HIDE_FULL;
+  mysql_mutex_unlock(&LOCK_global_system_variables);
   DBUG_RETURN(0);
 }
 
 static int forced_versioning_deinit(void *p __attribute__ ((unused)))
 {
   DBUG_ENTER("forced_versioning_deinit");
-  vers_force= false;
-  vers_hide= VERS_HIDE_AUTO;
+  mysql_mutex_lock(&LOCK_global_system_variables);
+  global_system_variables.vers_force= false;
+  global_system_variables.vers_hide= VERS_HIDE_AUTO;
+  mysql_mutex_unlock(&LOCK_global_system_variables);
   DBUG_RETURN(0);
 }
 
diff --git a/sql/handler.cc b/sql/handler.cc
index 62091b0f19e..13c4031b02d 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -6698,7 +6698,7 @@ bool Vers_parse_info::check_and_fix_implicit(
 
   // CREATE ... SELECT: if at least one table in SELECT is versioned,
   // then created table will be versioned.
-  if (vers_force || vers_tables > 0)
+  if (thd->variables.vers_force || vers_tables > 0)
   {
     declared_with_system_versioning= true;
     create_info->options|= HA_VERSIONED_TABLE;
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index 1696f689aab..454b5d10965 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -781,11 +781,6 @@ char *relay_log_info_file, *report_user, *report_password, *report_host;
 char *opt_relay_logname = 0, *opt_relaylog_index_name=0;
 char *opt_logname, *opt_slow_logname, *opt_bin_logname;
 
-/* System Versioning */
-char *temporal_current_timestamp;
-my_bool vers_force= false;
-ulong vers_hide= VERS_HIDE_AUTO;
-
 /* Static variables */
 
 static volatile sig_atomic_t kill_in_progress;
@@ -9315,6 +9310,17 @@ mysqld_get_one_option(int optid, const struct my_option *opt, char *argument)
               WSREP_SYNC_WAIT_BEFORE_READ);
     break;
 #endif /* WITH_WSREP */
+  case OPT_VERS_CURRENT_TIME:
+    sys_var *var= static_cast<sys_var*>(opt->app_type);
+    DBUG_ASSERT(var);
+    if (var->option_updated())
+    {
+      sql_print_error("Can't start server: "
+                      "cannot process --vers-current-time=%.*s",
+                      FN_REFLEN, argument);
+      return 1;
+    }
+    break;
   }
   return 0;
 }
diff --git a/sql/mysqld.h b/sql/mysqld.h
index 8cf14cc19a5..e8a72b0b063 100644
--- a/sql/mysqld.h
+++ b/sql/mysqld.h
@@ -175,15 +175,34 @@ extern char *opt_backup_history_logname, *opt_backup_progress_logname,
             *opt_backup_settings_name;
 extern const char *log_output_str;
 extern const char *log_backup_output_str;
-extern char *temporal_current_timestamp;
-extern my_bool vers_force;
+
+enum vers_range_type_t
+{
+  FOR_SYSTEM_TIME_UNSPECIFIED = 0,
+  FOR_SYSTEM_TIME_AS_OF,
+  FOR_SYSTEM_TIME_FROM_TO,
+  FOR_SYSTEM_TIME_BETWEEN,
+  FOR_SYSTEM_TIME_ALL,
+  FOR_SYSTEM_TIME_BEFORE
+};
+
+struct st_vers_current_time
+{ // This struct must be POD, so no virtual-anything!
+  char *str_value; // must be first
+  vers_range_type_t type;
+  MYSQL_TIME ltime;
+  st_vers_current_time() :
+    str_value(NULL),
+    type(FOR_SYSTEM_TIME_UNSPECIFIED)
+  {}
+};
+
 enum vers_hide_enum {
   VERS_HIDE_AUTO= 0,
   VERS_HIDE_IMPLICIT,
   VERS_HIDE_FULL,
   VERS_HIDE_NEVER
 };
-extern ulong vers_hide;
 extern char *mysql_home_ptr, *pidfile_name_ptr;
 extern MYSQL_PLUGIN_IMPORT char glob_hostname[FN_REFLEN];
 extern char mysql_home[FN_REFLEN];
@@ -652,6 +671,7 @@ enum options_mysqld
   OPT_SSL_KEY,
   OPT_THREAD_CONCURRENCY,
   OPT_WANT_CORE,
+  OPT_VERS_CURRENT_TIME,
 #ifdef WITH_WSREP
   OPT_WSREP_CAUSAL_READS,
   OPT_WSREP_SYNC_WAIT,
diff --git a/sql/set_var.h b/sql/set_var.h
index ddd6a225eb8..9c7d7f1135b 100644
--- a/sql/set_var.h
+++ b/sql/set_var.h
@@ -223,6 +223,13 @@ private:
   virtual bool session_update(THD *thd, set_var *var) = 0;
   virtual bool global_update(THD *thd, set_var *var) = 0;
 
+public:
+  virtual bool option_updated()
+  {
+    DBUG_ASSERT(false);
+    return true;
+  }
+
 protected:
   /**
     A pointer to a value of the variable for SHOW.
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index df50b2a7afa..d0c723af397 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -7478,6 +7478,7 @@ insert_fields(THD *thd, Name_resolution_context *context, const char *db_name,
   Field_iterator_table_ref field_iterator;
   bool found;
   char name_buff[SAFE_NAME_LEN+1];
+  ulong vers_hide= thd->variables.vers_hide;
   DBUG_ENTER("insert_fields");
   DBUG_PRINT("arena", ("stmt arena: 0x%lx", (ulong)thd->stmt_arena));
 
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 49f62f9ea4e..e3601f141fa 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -706,6 +706,10 @@ typedef struct system_variables
   uint idle_transaction_timeout;
   uint idle_readonly_transaction_timeout;
   uint idle_readwrite_transaction_timeout;
+
+  st_vers_current_time vers_current_time;
+  my_bool vers_force;
+  ulong vers_hide;
 } SV;
 
 /**
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 1c57ca2e77a..6739d51f360 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -670,24 +670,19 @@ setup_without_group(THD *thd, Ref_ptr_array ref_pointer_array,
 
 bool vers_select_conds_t::init_from_sysvar(THD *thd)
 {
-  const char var[]= "temporal_current_timestamp";
-  sys_var *sv= intern_find_sys_var(var, sizeof(var) - 1);
-  DBUG_ASSERT(sv);
-  const char *data= *(char **)sv->option.value;
-  DBUG_ASSERT(data);
-  if (0 == strcmp(data, "all"))
-  {
-    init(FOR_SYSTEM_TIME_ALL, UNIT_TIMESTAMP);
-  }
-  else if (0 != strcmp(data, "now"))
-  {
-    Item *ts=
-        create_temporal_literal(thd, data, strlen(data), system_charset_info,
-                                MYSQL_TYPE_DATETIME, true);
-    if (!ts)
+  st_vers_current_time &in= thd->variables.vers_current_time;
+  type= in.type;
+  unit= UNIT_TIMESTAMP;
+  if (type != FOR_SYSTEM_TIME_UNSPECIFIED && type != FOR_SYSTEM_TIME_ALL)
+  {
+    DBUG_ASSERT(type == FOR_SYSTEM_TIME_AS_OF);
+    start= new (thd->mem_root) Item_datetime_literal(thd, &in.ltime, 6);
+    if (!start)
       return true;
-    init(FOR_SYSTEM_TIME_AS_OF, UNIT_TIMESTAMP, ts);
   }
+  else
+    start= NULL;
+  end= NULL;
   return false;
 }
 
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index bedc32d6010..a3ce1fd19c6 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -1986,6 +1986,7 @@ int show_create_table(THD *thd, TABLE_LIST *table_list, String *packet,
   TABLE *table= table_list->table;
   TABLE_SHARE *share= table->s;
   sql_mode_t sql_mode= thd->variables.sql_mode;
+  ulong vers_hide= thd->variables.vers_hide;
   bool foreign_db_mode=  sql_mode & (MODE_POSTGRESQL | MODE_ORACLE |
                                      MODE_MSSQL | MODE_DB2 |
                                      MODE_MAXDB | MODE_ANSI);
diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
index 9fb32174d1c..0b80684cd77 100644
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -382,14 +382,14 @@ static Sys_var_charptr Sys_basedir(
        READ_ONLY GLOBAL_VAR(mysql_home_ptr), CMD_LINE(REQUIRED_ARG, 'b'),
        IN_FS_CHARSET, DEFAULT(0));
 
-static Sys_var_charptr sys_temporal_current_timestamp(
-       "temporal_current_timestamp", "Default AS OF value for versioned tables",
-       GLOBAL_VAR(temporal_current_timestamp), CMD_LINE(REQUIRED_ARG, 'b'),
+static Sys_var_vers_asof Sys_vers_current_time(
+       "vers_current_time", "Default AS OF value for versioned tables",
+       SESSION_VAR(vers_current_time), CMD_LINE(REQUIRED_ARG, OPT_VERS_CURRENT_TIME),
        IN_FS_CHARSET, DEFAULT("now"));
 
 static Sys_var_mybool Sys_vers_force(
        "vers_force", "Force system versioning for all created tables",
-       GLOBAL_VAR(vers_force), CMD_LINE(OPT_ARG), DEFAULT(FALSE));
+       SESSION_VAR(vers_force), CMD_LINE(OPT_ARG), DEFAULT(FALSE));
 
 static const char *vers_hide_keywords[]= {"AUTO", "IMPLICIT", "FULL", "NEVER", NullS};
 static Sys_var_enum Sys_vers_hide(
@@ -398,7 +398,7 @@ static Sys_var_enum Sys_vers_hide(
        "IMPLICIT: hide implicit system fields in all queries; "
        "FULL: hide any system fields in all queries and hide versioning info in SHOW commands; "
        "NEVER: don't hide system fields",
-       GLOBAL_VAR(vers_hide), CMD_LINE(OPT_ARG), vers_hide_keywords, DEFAULT(VERS_HIDE_AUTO));
+       SESSION_VAR(vers_hide), CMD_LINE(OPT_ARG), vers_hide_keywords, DEFAULT(VERS_HIDE_AUTO));
 
 static Sys_var_ulonglong Sys_binlog_cache_size(
        "binlog_cache_size", "The size of the transactional cache for "
diff --git a/sql/sys_vars.ic b/sql/sys_vars.ic
index 780450b484b..76bf8631630 100644
--- a/sql/sys_vars.ic
+++ b/sql/sys_vars.ic
@@ -2485,3 +2485,165 @@ public:
   bool global_update(THD *thd, set_var *var);
   uchar *global_value_ptr(THD *thd, const LEX_STRING *base);
 };
+
+
+class Sys_var_vers_asof: public sys_var
+{
+public:
+  Sys_var_vers_asof(
+    const char *name_arg,
+    const char *comment,
+    int flag_args,
+    ptrdiff_t off,
+    size_t size,
+    CMD_LINE getopt,
+    enum charset_enum is_os_charset_arg,
+    const char *def_val,
+    on_check_function on_check_func=0,
+    on_update_function on_update_func=0) :
+  sys_var(
+    &all_sys_vars,
+    name_arg,
+    comment,
+    flag_args,
+    off,
+    getopt.id,
+    getopt.arg_type,
+    SHOW_CHAR,
+    (intptr) def_val,
+    0,
+    VARIABLE_NOT_IN_BINLOG,
+    on_check_func,
+    on_update_func,
+    0)
+  {
+    option.var_type|= GET_STR;
+    if (global_update(def_val))
+    {
+      DBUG_ASSERT(false);
+    }
+  }
+
+  bool do_check(THD *thd, set_var *var)
+  { return false; }
+
+  bool update(String &in, st_vers_current_time &out)
+  {
+    if (in.length() == 3 &&
+      0 == my_strcasecmp(
+        in.charset(),
+        "ALL",
+        in.ptr()))
+    {
+      out.type= FOR_SYSTEM_TIME_ALL;
+    }
+    else if (in.length() == 3 &&
+      0 == my_strcasecmp(
+        in.charset(),
+        "NOW",
+        in.ptr()))
+    {
+      out.type= FOR_SYSTEM_TIME_UNSPECIFIED;
+    }
+    else
+    {
+      MYSQL_TIME_STATUS status;
+      if (str_to_datetime(
+            in.ptr(),
+            in.length(),
+            &out.ltime,
+            flags,
+            &status) ||
+          out.ltime.time_type != MYSQL_TIMESTAMP_DATETIME ||
+          (status.warnings & ~MYSQL_TIME_NOTE_TRUNCATED) != 0)
+      {
+        return true;
+      }
+      out.type= FOR_SYSTEM_TIME_AS_OF;
+    }
+    return false;
+  }
+  bool update(THD *thd, set_var *var, st_vers_current_time &out)
+  {
+    Item *item= var->value;
+
+    switch (item->result_type())
+    {
+    case TIME_RESULT:
+      {
+        if (item->get_date(&out.ltime, 0))
+          break;
+        out.type= FOR_SYSTEM_TIME_AS_OF;
+        return false;
+      }
+
+    case STRING_RESULT:
+      {
+        String *str= item->val_str();
+        if (!str || update(*str, out))
+          break;
+        return false;
+      }
+    default:
+      break;
+    }
+    String *str= item->val_str();
+    const char *cstr= str ? str->c_ptr_safe() : "NULL";
+    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), var->var->name.str, cstr);
+    return true;
+  }
+  bool global_update(const char *in)
+  {
+    String s(in, &my_charset_utf8_general_ci);
+    return update(s, global_var(st_vers_current_time));
+  }
+  bool option_updated()
+  {
+    return global_update(global_var(st_vers_current_time).str_value);
+  }
+  bool global_update(THD *thd, set_var *var)
+  {
+    return update(thd, var, global_var(st_vers_current_time));
+  }
+  bool session_update(THD *thd, set_var *var)
+  {
+    return update(thd, var, session_var(thd, st_vers_current_time));
+  }
+  uchar *valptr(THD *thd, st_vers_current_time &val)
+  {
+    switch (val.type)
+    {
+    case FOR_SYSTEM_TIME_UNSPECIFIED:
+      return (uchar*) thd->strdup("NOW");
+    case FOR_SYSTEM_TIME_ALL:
+      return (uchar*) thd->strdup("ALL");
+    case FOR_SYSTEM_TIME_AS_OF:
+      {
+        uchar *buf= (uchar*) thd->alloc(MAX_DATE_STRING_REP_LENGTH);
+        if (buf)
+        {
+          if (!my_datetime_to_str(&val.ltime, (char*) buf, 6))
+          {
+            my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), "vers_current_time", "NULL (wrong datetime)");
+            return (uchar*) thd->strdup("Error: wrong datetime");
+          }
+        }
+        return buf;
+      }
+    default:
+      break;
+    }
+    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), "vers_current_time", "NULL (wrong range type)");
+    return (uchar*) thd->strdup("Error: wrong range type");
+  }
+  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, const LEX_STRING *base)
+  { return valptr(thd, session_var(thd, st_vers_current_time)); }
+  uchar *global_value_ptr(THD *thd, const LEX_STRING *base)
+  { return valptr(thd, global_var(st_vers_current_time)); }
+  uchar *default_value_ptr(THD *thd)
+  { return (uchar *)option.def_value; }
+};
diff --git a/sql/table.h b/sql/table.h
index ba497f1c365..f6736658674 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -1841,16 +1841,6 @@ class Item_in_subselect;
   4) jtbm semi-join (jtbm_subselect != NULL)
 */
 
-enum vers_range_type_t
-{
-  FOR_SYSTEM_TIME_UNSPECIFIED = 0,
-  FOR_SYSTEM_TIME_AS_OF,
-  FOR_SYSTEM_TIME_FROM_TO,
-  FOR_SYSTEM_TIME_BETWEEN,
-  FOR_SYSTEM_TIME_ALL,
-  FOR_SYSTEM_TIME_BEFORE
-};
-
 enum vers_range_unit_t
 {
   UNIT_TIMESTAMP = 0,