From 62470fc7874515e2bc8bc00cb38844f19c465d7e Mon Sep 17 00:00:00 2001
From: Eugene Kosov <claprix@yandex.ru>
Date: Fri, 24 Nov 2017 21:26:43 +0300
Subject: [PATCH] SQL: recreate PRIMARY KEY on DROP SYSTEM VERSIONING [#348]

---
 mysql-test/suite/versioning/t/alter.test | 17 +++++++
 sql/handler.cc                           | 59 ++++++++++++++++++++++++
 2 files changed, 76 insertions(+)

diff --git a/mysql-test/suite/versioning/t/alter.test b/mysql-test/suite/versioning/t/alter.test
index 71b40c73a2f..e75974f8324 100644
--- a/mysql-test/suite/versioning/t/alter.test
+++ b/mysql-test/suite/versioning/t/alter.test
@@ -320,6 +320,23 @@ alter table non_empty
   change column sys_trx_end sys_trx_end bigint(20) unsigned generated always as row end;
 drop table non_empty;
 
+create or replace table t (a int primary key) with system versioning;
+insert into t values (1);
+update t set a=2;
+alter table t drop primary key, add primary key (a), drop system versioning;
+select * from t;
+--replace_result InnoDB INNODB_OR_MYISAM MyISAM INNODB_OR_MYISAM
+show create table t;
+
+create or replace table t (a int primary key) with system versioning;
+insert into t values (1);
+update t set a=2;
+alter table t drop system versioning;
+select * from t;
+--replace_result InnoDB INNODB_OR_MYISAM MyISAM INNODB_OR_MYISAM
+show create table t;
+
+
 call verify_vtq;
 }
 
diff --git a/sql/handler.cc b/sql/handler.cc
index c6837fd5bd0..9299102ba58 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -6927,6 +6927,29 @@ static bool add_field_to_drop_list(THD *thd, Alter_info *alter_info,
   return !ad || alter_info->drop_list.push_back(ad, thd->mem_root);
 }
 
+static bool is_dropping_primary_key(Alter_info *alter_info)
+{
+  List_iterator_fast<Alter_drop> it(alter_info->drop_list);
+  while (Alter_drop *ad= it++)
+  {
+    if (ad->type == Alter_drop::KEY &&
+        !my_strcasecmp(system_charset_info, ad->name, primary_key_name))
+      return true;
+  }
+  return false;
+}
+
+static bool is_adding_primary_key(Alter_info *alter_info)
+{
+  List_iterator_fast<Key> it(alter_info->key_list);
+  while (Key *key= it++)
+  {
+    if (key->type == Key::PRIMARY)
+      return true;
+  }
+  return false;
+}
+
 bool Vers_parse_info::check_and_fix_alter(THD *thd, Alter_info *alter_info,
                                           HA_CREATE_INFO *create_info,
                                           TABLE *table)
@@ -6964,6 +6987,42 @@ bool Vers_parse_info::check_and_fix_alter(THD *thd, Alter_info *alter_info,
         add_field_to_drop_list(thd, alter_info, share->vers_end_field()))
       return true;
 
+    if (share->primary_key != MAX_KEY && !is_adding_primary_key(alter_info) &&
+        !is_dropping_primary_key(alter_info))
+    {
+      alter_info->flags|= Alter_info::ALTER_DROP_INDEX;
+      Alter_drop *ad= new (thd->mem_root)
+          Alter_drop(Alter_drop::KEY, primary_key_name, false);
+      if (!ad || alter_info->drop_list.push_back(ad, thd->mem_root))
+        return true;
+
+      alter_info->flags|= Alter_info::ALTER_ADD_INDEX;
+      LEX_CSTRING key_name= {NULL, 0};
+      DDL_options_st options;
+      options.init();
+      Key *pk= new (thd->mem_root)
+          Key(Key::PRIMARY, &key_name, HA_KEY_ALG_UNDEF, false, options);
+      if (!pk)
+        return true;
+
+      st_key &key= table->key_info[share->primary_key];
+      for (st_key_part_info *it= key.key_part,
+                            *end= it + key.user_defined_key_parts;
+           it != end; ++it)
+      {
+        if (it->field->vers_sys_field())
+          continue;
+
+        Key_part_spec *key_part_spec= new (thd->mem_root)
+            Key_part_spec(&it->field->field_name, it->length);
+        if (!key_part_spec ||
+            pk->columns.push_back(key_part_spec, thd->mem_root))
+          return true;
+      }
+
+      alter_info->key_list.push_back(pk);
+    }
+
     return false;
   }