MDEV-7318 RENAME INDEX

This patch adds support of RENAME INDEX operation to the ALTER TABLE
statement. Code which determines if ALTER TABLE can be done in-place
for "simple" storage engines like MyISAM, Heap and etc. was updated to
handle ALTER TABLE ... RENAME INDEX as an in-place operation. Support
for in-place ALTER TABLE ... RENAME INDEX for InnoDB was covered by
MDEV-13301.

Syntax changes
==============

A new type of <alter_specification> is added:

<rename index clause> ::= RENAME ( INDEX | KEY ) <oldname> TO <newname>

Where <oldname> and <newname> are identifiers for old name and new
name of the index.

Semantic changes
================

The result of "ALTER TABLE t1 RENAME INDEX a TO b" is a table which
contents and structure are identical to the old version of 't1' with
the only exception index 'a' being called 'b'.

Neither <oldname> nor <newname> can be "primary". The index being
renamed should exist and its new name should not be occupied
by another index on the same table.

Related to: WL#6555, MDEV-13301

6 files changed, 75 insertions, 2 deletions

diff --git a/sql/handler.cc b/sql/handler.cc
index 7d61252eea6..806d91bdbc5 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -4585,7 +4585,8 @@ handler::check_if_supported_inplace_alter(TABLE *altered_table,
     ALTER_DROP_CHECK_CONSTRAINT |
     ALTER_PARTITIONED |
     ALTER_VIRTUAL_GCOL_EXPR |
-    ALTER_RENAME;
+    ALTER_RENAME |
+    ALTER_RENAME_INDEX;
 
   /* Is there at least one operation that requires copy algorithm? */
   if (ha_alter_info->handler_flags & ~inplace_offline_operations)
diff --git a/sql/sql_alter.cc b/sql/sql_alter.cc
index 0828e1b7ba8..23e2e3e097f 100644
--- a/sql/sql_alter.cc
+++ b/sql/sql_alter.cc
@@ -25,6 +25,7 @@ Alter_info::Alter_info(const Alter_info &rhs, MEM_ROOT *mem_root)
   :drop_list(rhs.drop_list, mem_root),
   alter_list(rhs.alter_list, mem_root),
   key_list(rhs.key_list, mem_root),
+  alter_rename_key_list(rhs.alter_rename_key_list, mem_root),
   create_list(rhs.create_list, mem_root),
   check_constraint_list(rhs.check_constraint_list, mem_root),
   flags(rhs.flags), partition_flags(rhs.partition_flags),
@@ -46,6 +47,7 @@ Alter_info::Alter_info(const Alter_info &rhs, MEM_ROOT *mem_root)
   list_copy_and_replace_each_value(drop_list, mem_root);
   list_copy_and_replace_each_value(alter_list, mem_root);
   list_copy_and_replace_each_value(key_list, mem_root);
+  list_copy_and_replace_each_value(alter_rename_key_list, mem_root);
   list_copy_and_replace_each_value(create_list, mem_root);
   /* partition_names are not deeply copied currently */
 }
diff --git a/sql/sql_alter.h b/sql/sql_alter.h
index 41408a91836..a553c31346a 100644
--- a/sql/sql_alter.h
+++ b/sql/sql_alter.h
@@ -19,6 +19,7 @@
 
 class Alter_drop;
 class Alter_column;
+class Alter_rename_key;
 class Key;
 
 /**
@@ -87,6 +88,8 @@ public:
   List<Alter_column>            alter_list;
   // List of keys, used by both CREATE and ALTER TABLE.
   List<Key>                     key_list;
+  // List of keys to be renamed.
+  List<Alter_rename_key>        alter_rename_key_list;
   // List of columns, used by both CREATE and ALTER TABLE.
   List<Create_field>            create_list;
 
@@ -123,6 +126,7 @@ public:
     drop_list.empty();
     alter_list.empty();
     key_list.empty();
+    alter_rename_key_list.empty();
     create_list.empty();
     check_constraint_list.empty();
     flags= 0;
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 6a7c0cd4d94..123bf0c0583 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -355,6 +355,21 @@ public:
 };
 
 
+class Alter_rename_key : public Sql_alloc
+{
+public:
+  LEX_CSTRING old_name;
+  LEX_CSTRING new_name;
+
+  Alter_rename_key(LEX_CSTRING old_name_arg, LEX_CSTRING new_name_arg)
+      : old_name(old_name_arg), new_name(new_name_arg) {}
+
+  Alter_rename_key *clone(MEM_ROOT *mem_root) const
+    { return new (mem_root) Alter_rename_key(*this); }
+
+};
+
+
 class Key :public Sql_alloc, public DDL_options {
 public:
   enum Keytype { PRIMARY, UNIQUE, MULTIPLE, FULLTEXT, SPATIAL, FOREIGN_KEY};
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index b5cc07b1411..3b56a721801 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -6601,7 +6601,7 @@ static int compare_uint(const uint *s, const uint *t)
 
 enum class Compare_keys : uint32_t
 {
-  Equal,
+  Equal= 0,
   EqualButKeyPartLength,
   EqualButComment,
   NotEqual
@@ -7998,6 +7998,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
   List<Create_field> new_create_list;
   /* New key definitions are added here */
   List<Key> new_key_list;
+  List<Alter_rename_key> rename_key_list(alter_info->alter_rename_key_list);
   List_iterator<Alter_drop> drop_it(alter_info->drop_list);
   List_iterator<Create_field> def_it(alter_info->create_list);
   List_iterator<Alter_column> alter_it(alter_info->alter_list);
@@ -8446,6 +8447,39 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
       continue;
     }
 
+    /* If this index is to stay in the table check if it has to be renamed. */
+    List_iterator<Alter_rename_key> rename_key_it(rename_key_list);
+    Alter_rename_key *rename_key;
+
+    while ((rename_key= rename_key_it++))
+    {
+      if (!my_strcasecmp(system_charset_info, key_name, rename_key->old_name.str))
+      {
+        if (!my_strcasecmp(system_charset_info, key_name, primary_key_name))
+        {
+          my_error(ER_WRONG_NAME_FOR_INDEX, MYF(0), rename_key->old_name.str);
+          goto err;
+        }
+        else if (!my_strcasecmp(system_charset_info, rename_key->new_name.str,
+                                primary_key_name))
+        {
+          my_error(ER_WRONG_NAME_FOR_INDEX, MYF(0), rename_key->new_name.str);
+          goto err;
+        }
+
+        key_name= rename_key->new_name.str;
+        rename_key_it.remove();
+        /*
+          If the user has explicitly renamed the key, we should no longer
+          treat it as generated. Otherwise this key might be automatically
+          dropped by mysql_prepare_create_table() and this will confuse
+          code in fill_alter_inplace_info().
+        */
+        key_info->flags&= ~HA_GENERATED_KEY;
+        break;
+      }
+    }
+
     if (key_info->algorithm == HA_KEY_ALG_LONG_HASH)
     {
       setup_keyinfo_hash(key_info);
@@ -8772,6 +8806,13 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
     }
   }
 
+  if (rename_key_list.elements)
+  {
+    my_error(ER_KEY_DOES_NOT_EXITS, MYF(0), rename_key_list.head()->old_name.str,
+             table->s->table_name.str);
+    goto err;
+  }
+
   if (!create_info->comment.str)
   {
     create_info->comment.str= table->s->comment.str;
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 1d4a8a7e228..b032ce66cc7 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -7732,6 +7732,16 @@ alter_list_item:
             if (unlikely(Lex->add_alter_list($3, $5)))
               MYSQL_YYABORT;
           }
+        | RENAME key_or_index field_ident TO_SYM field_ident
+          {
+            LEX *lex=Lex;
+            Alter_rename_key *ak= new (thd->mem_root)
+                                    Alter_rename_key($3, $5);
+            if (ak == NULL)
+              MYSQL_YYABORT;
+            lex->alter_info.alter_rename_key_list.push_back(ak);
+            lex->alter_info.flags|= ALTER_RENAME_INDEX;
+          }
         | CONVERT_SYM TO_SYM charset charset_name_or_default opt_collate
           {
             if (!$4)