MDEV-13508 ALTER TABLE that renames columns and CHECK constraints

Fixed by adding Item::rename_fields_processor
Signed-off-by: Monty <monty@mariadb.org>

mysql-test/r/alter_table.result

@@ -2276,5 +2276,38 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 #
+# MDEV-13508 Check that rename of columns changes defaults, virtual
+# columns and constraints
+#
+create table t1 (a int, b int, check(a>b));
+alter table t1 change column a b int, change column b a int;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `b` int(11) DEFAULT NULL,
+  `a` int(11) DEFAULT NULL,
+  CONSTRAINT `CONSTRAINT_1` CHECK (`b` > `a`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
+create table t1 (a int primary key, b int, c int default (a+b) check (a+b>0),
+d int as (a+b),
+key (b),
+constraint test check (a+b > 1));
+alter table t1 change b new_b int not null, add column b char(1), add constraint new check (length(b) > 0);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) NOT NULL,
+  `new_b` int(11) NOT NULL,
+  `c` int(11) DEFAULT (`a` + `new_b`) CHECK (`a` + `new_b` > 0),
+  `d` int(11) GENERATED ALWAYS AS (`a` + `new_b`) VIRTUAL,
+  `b` char(1) DEFAULT NULL,
+  PRIMARY KEY (`a`),
+  KEY `b` (`new_b`),
+  CONSTRAINT `test` CHECK (`a` + `new_b` > 1),
+  CONSTRAINT `new` CHECK (length(`b`) > 0)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
+#
 # End of 10.2 tests
 #

mysql-test/t/alter_table.test

@@ -1882,6 +1882,24 @@ alter table t1 drop column a, drop index a;
 show create table t1;
 drop table t1;
 
+--echo #
+--echo # MDEV-13508 Check that rename of columns changes defaults, virtual
+--echo # columns and constraints
+--echo #
+
+create table t1 (a int, b int, check(a>b));
+alter table t1 change column a b int, change column b a int;
+show create table t1;
+drop table t1;
+
+create table t1 (a int primary key, b int, c int default (a+b) check (a+b>0),
+                d int as (a+b),
+	        key (b),
+	        constraint test check (a+b > 1));
+alter table t1 change b new_b int not null, add column b char(1), add constraint new check (length(b) > 0);
+show create table t1;
+drop table t1;
+
 --echo #
 --echo # End of 10.2 tests
 --echo #

sql/item.cc

@@ -885,6 +885,34 @@ bool Item_field::add_field_to_set_processor(void *arg)
   DBUG_RETURN(FALSE);
 }
 
+
+/**
+   Rename fields in an expression to new field name as speficied by ALTER TABLE
+*/
+
+bool Item_field::rename_fields_processor(void *arg)
+{
+  Item::func_processor_rename *rename= (Item::func_processor_rename*) arg;
+  List_iterator<Create_field> def_it(rename->fields);
+  Create_field *def;
+
+  while ((def=def_it++))
+  {
+    if (def->change &&
+        (!db_name || !db_name[0] ||
+         !my_strcasecmp(table_alias_charset, db_name, rename->db_name.str)) &&
+        (!table_name || !table_name[0] ||
+         !my_strcasecmp(table_alias_charset, table_name, rename->table_name.str)) &&
+        !my_strcasecmp(system_charset_info, field_name, def->change))
+    {
+      field_name= def->field_name;
+      break;
+    }
+  }
+  return 0;
+}
+
+
 /**
   Check if an Item_field references some field from a list of fields.
 

sql/item.h

@@ -1667,6 +1667,7 @@ class Item: public Value_source,
   */
   virtual bool check_partition_func_processor(void *arg) { return 1;}
   virtual bool vcol_in_partition_func_processor(void *arg) { return 0; }
+  virtual bool rename_fields_processor(void *arg) { return 0; }
   /** Processor used to check acceptability of an item in the defining
       expression for a virtual column 
 
@@ -1680,6 +1681,12 @@ class Item: public Value_source,
     uint errors;                                /* Bits of possible errors */
     const char *name;                           /* Not supported function */
   };
+  struct func_processor_rename
+  {
+    LEX_CSTRING db_name;
+    LEX_CSTRING table_name;
+    List<Create_field> fields;
+  };
   virtual bool check_vcol_func_processor(void *arg)
   {
     return mark_unsupported_function(full_name(), arg, VCOL_IMPOSSIBLE);
@@ -2639,6 +2646,7 @@ class Item_field :public Item_ident
   bool update_table_bitmaps_processor(void *arg);
   bool switch_to_nullable_fields_processor(void *arg);
   bool update_vcol_processor(void *arg);
+  bool rename_fields_processor(void *arg);
   bool check_vcol_func_processor(void *arg)
   {
     context= 0;

sql/sql_alter.h

@@ -123,6 +123,7 @@ class Alter_info
 
   static const uint ALTER_ADD_CHECK_CONSTRAINT  = 1L << 27;
   static const uint ALTER_DROP_CHECK_CONSTRAINT = 1L << 28;
+  static const uint ALTER_RENAME_COLUMN         = 1L << 29;
 
   enum enum_enable_or_disable { LEAVE_AS_IS, ENABLE, DISABLE };
 

sql/sql_list.cc

@@ -38,21 +38,21 @@ void free_list(I_List <i_string> *list)
 }
 
 
-base_list::base_list(const base_list &rhs, MEM_ROOT *mem_root)
+bool base_list::copy(const base_list *rhs, MEM_ROOT *mem_root)
 {
-  if (rhs.elements)
+  bool error= 0;
+  if (rhs->elements)
   {
     /*
       It's okay to allocate an array of nodes at once: we never
       call a destructor for list_node objects anyway.
     */
-    first= (list_node*) alloc_root(mem_root,
-                                   sizeof(list_node) * rhs.elements);
-    if (first)
+    if ((first= (list_node*) alloc_root(mem_root,
+                                        sizeof(list_node) * rhs->elements)))
     {
-      elements= rhs.elements;
+      elements= rhs->elements;
       list_node *dst= first;
-      list_node *src= rhs.first;
+      list_node *src= rhs->first;
       for (; dst < first + elements - 1; dst++, src= src->next)
       {
         dst->info= src->info;
@@ -63,10 +63,12 @@ base_list::base_list(const base_list &rhs, MEM_ROOT *mem_root)
       dst->next= &end_of_list;
       /* Setup 'last' member */
       last= &dst->next;
-      return;
+      return 0;
     }
+    error= 1;
   }
   elements= 0;
   first= &end_of_list;
   last= &first;
+  return error;
 }

sql/sql_list.h

@@ -200,7 +200,8 @@ class base_list :public Sql_alloc
     need to copy elements by value, you should employ
     list_copy_and_replace_each_value after creating a copy.
   */
-  base_list(const base_list &rhs, MEM_ROOT *mem_root);
+  bool copy(const base_list *rhs, MEM_ROOT *mem_root);
+  base_list(const base_list &rhs, MEM_ROOT *mem_root) { copy(&rhs, mem_root); }
   inline base_list(bool error) { }
   inline bool push_back(void *info)
   {
@@ -536,6 +537,8 @@ template <class T> class List :public base_list
   inline void disjoin(List<T> *list) { base_list::disjoin(list); }
   inline bool add_unique(T *a, bool (*eq)(T *a, T *b))
   { return base_list::add_unique(a, (List_eq *)eq); }
+  inline bool copy(const List<T> *list, MEM_ROOT *root)
+  { return base_list::copy(list, root); }
   void delete_elements(void)
   {
     list_node *element,*next;

sql/sql_table.cc

@@ -7558,6 +7558,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
   List<Virtual_column_info> new_constraint_list;
   uint db_create_options= (table->s->db_create_options
                            & ~(HA_OPTION_PACK_RECORD));
+  Item::func_processor_rename column_rename_param;
   uint used_fields;
   KEY *key_info=table->key_info;
   bool rc= TRUE;
@@ -7607,6 +7608,13 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
   if (!(used_fields & HA_CREATE_USED_CONNECTION))
     create_info->connect_string= table->s->connect_string;
 
+  column_rename_param.db_name.str=       table->s->db.str;
+  column_rename_param.db_name.length=    table->s->db.length;
+  column_rename_param.table_name.str=    table->s->table_name.str;
+  column_rename_param.table_name.length= table->s->table_name.length;
+  if (column_rename_param.fields.copy(&alter_info->create_list, thd->mem_root))
+    DBUG_RETURN(1);                             // OOM
+
   restore_record(table, s->default_values);     // Empty record for DEFAULT
 
   if ((create_info->fields_option_struct= (ha_field_option_struct**)
@@ -7651,6 +7659,24 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
       bitmap_set_bit(dropped_fields, field->field_index);
       continue;
     }
+
+    /*
+      If we are doing a rename of a column, update all references in virtual
+      column expressions, constraints and defaults to use the new column name
+    */
+    if (alter_info->flags & Alter_info::ALTER_RENAME_COLUMN)
+    {
+      if (field->vcol_info)
+        field->vcol_info->expr->walk(&Item::rename_fields_processor, 1,
+                                     &column_rename_param);
+      if (field->check_constraint)
+        field->check_constraint->expr->walk(&Item::rename_fields_processor, 1,
+                                            &column_rename_param);
+      if (field->default_value)
+        field->default_value->expr->walk(&Item::rename_fields_processor, 1,
+                                         &column_rename_param);
+    }
+
     /* Check if field is changed */
     def_it.rewind();
     while ((def=def_it++))
@@ -8060,7 +8086,10 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
         }
       }
       if (!drop)
+      {
+        check->expr->walk(&Item::rename_fields_processor, 1, &column_rename_param);
         new_constraint_list.push_back(check, thd->mem_root);
+      }
     }
   }
   /* Add new constraints */

sql/sql_yacc.yy

@@ -7606,7 +7606,8 @@ alter_list_item:
         | CHANGE opt_column opt_if_exists_table_element field_ident
           field_spec opt_place
           {
-            Lex->alter_info.flags|= Alter_info::ALTER_CHANGE_COLUMN;
+            Lex->alter_info.flags|= (Alter_info::ALTER_CHANGE_COLUMN |
+                                     Alter_info::ALTER_RENAME_COLUMN);
             Lex->create_last_non_select_table= Lex->last_table();
             $5->change= $4.str;
             $5->after= $6;