added implicitly generated fields in versioned tables support and refactored code a bit

mysql-test/r/create.result

@@ -1932,6 +1932,19 @@ t1	CREATE TABLE `t1` (
   PERIOD FOR SYSTEM_TIME (`Sys_start`, `Sys_end`)
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 WITH SYSTEM VERSIONING
 drop table if exists t1;
+# Versioning fields are set implicitly.
+create table t1 (
+XNo INT UNSIGNED
+) WITH SYSTEM VERSIONING;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `XNo` int(10) unsigned DEFAULT NULL,
+  `sys_trx_start` timestamp(6) NULL GENERATED AS ROW START,
+  `sys_trx_end` timestamp(6) NULL GENERATED AS ROW END,
+  PERIOD FOR SYSTEM_TIME (`sys_trx_start`, `sys_trx_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1 WITH SYSTEM VERSIONING
+drop table if exists t1;
 create table t1 (
 XNo INT UNSIGNED,
 Sys_start TIMESTAMP(6) GENERATED ALWAYS AS ROW START,

mysql-test/t/create.test

@@ -1781,6 +1781,14 @@ SHOW CREATE TABLE t1;
 
 drop table if exists t1;
 
+--echo # Versioning fields are set implicitly.
+create table t1 (
+  XNo INT UNSIGNED
+) WITH SYSTEM VERSIONING;
+SHOW CREATE TABLE t1;
+
+drop table if exists t1;
+
 --error ER_SYS_START_MORE_THAN_ONCE
 create table t1 (
   XNo INT UNSIGNED,

sql/handler.cc

@@ -6326,3 +6326,53 @@ bool HA_CREATE_INFO::check_conflicting_charset_declarations(CHARSET_INFO *cs)
   }
   return false;
 }
+
+static bool create_string(MEM_ROOT *mem_root, String **s, const char *value)
+{
+  *s= new (mem_root) String(value, system_charset_info);
+  return *s == NULL;
+}
+
+static bool create_sys_trx_field_if_missing(THD *thd, const char *field_name,
+                                            Alter_info *alter_info, String **s)
+{
+  Create_field *f= new (thd->mem_root) Create_field();
+  if (!f)
+    return true;
+
+  f->field_name= field_name;
+  f->charset= system_charset_info;
+  f->sql_type= MYSQL_TYPE_TIMESTAMP;
+  f->length= 6;
+  f->decimals= 0;
+
+  if (f->check(thd))
+    return true;
+
+  if (create_string(thd->mem_root, s, field_name))
+    return true;
+
+  alter_info->create_list.push_back(f);
+  return false;
+}
+
+bool System_versioning_info::add_implicit_fields(THD *thd,
+                                                 Alter_info *alter_info)
+{
+  if (!declared_system_versioning)
+    return false;
+
+  // If user specified some of these he must specify the others too. Do nothing.
+  if (generated_as_row.start || generated_as_row.end ||
+      period_for_system_time.start || period_for_system_time.end)
+    return false;
+
+  return create_sys_trx_field_if_missing(thd, "sys_trx_start", alter_info,
+                                         &generated_as_row.start) ||
+         create_sys_trx_field_if_missing(thd, "sys_trx_end", alter_info,
+                                         &generated_as_row.end) ||
+         create_string(thd->mem_root, &period_for_system_time.start,
+                       "sys_trx_start") ||
+         create_string(thd->mem_root, &period_for_system_time.end,
+                       "sys_trx_end");
+}

sql/handler.h

@@ -1642,6 +1642,9 @@ struct System_versioning_info
     set_period_for_system_time(NULL, NULL);
   }
 
+  /** Returns true on failure */
+  bool add_implicit_fields(THD *thd, Alter_info *alter_info);
+
   /** User has added 'WITH SYSTEM VERSIONING' to table definition */
   bool declared_system_versioning;
 
@@ -1729,11 +1732,17 @@ struct Table_scope_and_contents_source_st
                          : ha_default_handlerton(thd);
   }
 
-  bool versioned()
+  bool versioned() const
   {
     return system_versioning_info.versioned;
   }
-  const System_versioning_info *get_system_versioning_info()
+  const System_versioning_info *get_system_versioning_info() const
+  {
+    if (!versioned())
+      return NULL;
+    return &system_versioning_info;
+  }
+  System_versioning_info *get_system_versioning_info()
   {
     if (!versioned())
       return NULL;

sql/sql_lex.h

@@ -3021,10 +3021,9 @@ struct LEX: public Query_tables_list
   bool tmp_table() const { return create_info.tmp_table(); }
   bool if_exists() const { return create_info.if_exists(); }
 
-  System_versioning_info *vers_get_info()
+  System_versioning_info &vers_get_info()
   {
-    create_info.system_versioning_info.versioned = true;
-    return &create_info.system_versioning_info;
+    return create_info.system_versioning_info;
   }
 };
 

sql/sql_parse.cc

@@ -3611,17 +3611,20 @@ mysql_execute_command(THD *thd)
       copy.
     */
     Alter_info alter_info(lex->alter_info, thd->mem_root);
-
-    if (check_system_versioning(&create_info))
-      goto end_with_restore_list;
-
     if (thd->is_fatal_error)
     {
       /* If out of memory when creating a copy of alter_info. */
       res= 1;
       goto end_with_restore_list;
     }
 
+    if (System_versioning_info *info= create_info.get_system_versioning_info())
+      if (info->add_implicit_fields(thd, &alter_info))
+        goto end_with_restore_list;
+
+    if (check_system_versioning(&create_info))
+      goto end_with_restore_list;
+
     /* Check privileges */
     if ((res= create_table_precheck(thd, select_tables, create_table)))
       goto end_with_restore_list;

sql/sql_yacc.yy

@@ -6053,10 +6053,9 @@ create_table_option:
           }
         | WITH SYSTEM VERSIONING
           {
-            System_versioning_info *info = Lex->vers_get_info();
-            if (!info)
-              MYSQL_YYABORT;
-            info->declared_system_versioning = true;
+            System_versioning_info &info= Lex->vers_get_info();
+            info.declared_system_versioning= true;
+            info.versioned= true;
           }
         ;
 
@@ -6258,15 +6257,14 @@ period_for_system_time:
           // If FOR_SYM is followed by SYSTEM_TIME_SYM then they are merged to: FOR_SYSTEM_TIME_SYM .
           PERIOD_SYM FOR_SYSTEM_TIME_SYM '(' period_for_system_time_column_id ',' period_for_system_time_column_id ')'
           {
-            System_versioning_info *info = Lex->vers_get_info();
-            if (!info)
-              MYSQL_YYABORT;
+            System_versioning_info &info= Lex->vers_get_info();
             if (!my_strcasecmp(system_charset_info, $4->c_ptr(), $6->c_ptr()))
             {
               my_error(ER_SYS_START_AND_SYS_END_SAME, MYF(0), $4->c_ptr());
               MYSQL_YYABORT;
             }
-            info->set_period_for_system_time($4, $6);
+            info.set_period_for_system_time($4, $6);
+            info.versioned= true;
           }
         ;
 
@@ -6333,26 +6331,24 @@ field_def:
           vcol_opt_specifier vcol_opt_attribute
         | opt_generated_always AS ROW_SYM start_or_end
           {
-            System_versioning_info *info =
-              Lex->vers_get_info();
-            if (!info)
-              MYSQL_YYABORT;
-            String *field_name = new (thd->mem_root)
+            System_versioning_info &info= Lex->vers_get_info();
+            info.versioned= true;
+            String *field_name= new (thd->mem_root)
               String((const char*)Lex->last_field->field_name, system_charset_info);
             if (!field_name)
               MYSQL_YYABORT;
 
-            String **p = NULL;
-            int err_nr = 0;
+            String **p= NULL;
+            int err_nr= 0;
             switch ($4)
             {
             case 1:
-              p = &info->generated_as_row.start;
-              err_nr = ER_SYS_START_MORE_THAN_ONCE;
+              p= &info.generated_as_row.start;
+              err_nr= ER_SYS_START_MORE_THAN_ONCE;
               break;
             case 0:
-              p = &info->generated_as_row.end;
-              err_nr = ER_SYS_END_MORE_THAN_ONCE;
+              p= &info.generated_as_row.end;
+              err_nr= ER_SYS_END_MORE_THAN_ONCE;
               break;
             default:
               /* Not Reachable */
@@ -6364,7 +6360,7 @@ field_def:
               my_error(err_nr, MYF(0), field_name->c_ptr());
               MYSQL_YYABORT;
             }
-            *p = field_name;
+            *p= field_name;
           }
         ;