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

Author: kevgs

mysql-test/r/create.result

@@ -1949,6 +1949,19 @@ 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

@@ -1799,6 +1799,14 @@ 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

@@ -6552,3 +6552,53 @@ int del_global_index_stat(THD *thd, TABLE* table, KEY* key_info)
  mysql_mutex_unlock(&LOCK_global_index_stats);
  DBUG_RETURN(res);
 }
+
+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

@@ -1683,6 +1683,9 @@ 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;
 
@@ -1777,11 +1780,17 @@ 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

@@ -3561,10 +3561,9 @@ struct LEX: public Query_tables_list
  bool add_unit_in_brackets(SELECT_LEX *nselect);
  void check_automatic_up(enum sub_select_type type);
 
- 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

@@ -3849,17 +3849,20 @@ 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

@@ -5852,10 +5852,9 @@ 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;
  }
  ;
 
@@ -6060,15 +6059,14 @@ 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;
  }
  ;
 
@@ -6168,26 +6166,24 @@ 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 */
@@ -6199,7 +6195,7 @@ field_def:
  my_error(err_nr, MYF(0), field_name->c_ptr());
  MYSQL_YYABORT;
  }
- *p = field_name;
+ *p= field_name;
  }
  ;