cleanup: fill_alter_inplace_info

remove attempts to track "candidate keys", use what was already
decided in create_table_impl().

sql/sql_table.cc

@@ -5691,7 +5691,8 @@ static bool is_candidate_key(KEY *key)
   KEY_PART_INFO *key_part;
   KEY_PART_INFO *key_part_end= key->key_part + key->user_defined_key_parts;
 
-  if (!(key->flags & HA_NOSAME) || (key->flags & HA_NULL_PART_KEY))
+  if (!(key->flags & HA_NOSAME) || (key->flags & HA_NULL_PART_KEY) ||
+      (key->flags & HA_KEY_HAS_PART_KEY_SEG))
     return false;
 
   for (key_part= key->key_part; key_part < key_part_end; key_part++)
@@ -6157,17 +6158,14 @@ static int compare_uint(const uint *s, const uint *t)
    @retval false success
 */
 
-static bool fill_alter_inplace_info(THD *thd,
-                                    TABLE *table,
-                                    bool varchar,
+static bool fill_alter_inplace_info(THD *thd, TABLE *table, bool varchar,
                                     Alter_inplace_info *ha_alter_info)
 {
   Field **f_ptr, *field;
   List_iterator_fast<Create_field> new_field_it;
   Create_field *new_field;
   KEY_PART_INFO *key_part, *new_part;
   KEY_PART_INFO *end;
-  uint candidate_key_count= 0;
   Alter_info *alter_info= ha_alter_info->alter_info;
   DBUG_ENTER("fill_alter_inplace_info");
 
@@ -6443,8 +6441,13 @@ static bool fill_alter_inplace_info(THD *thd,
     Primary key index for the new table
   */
   const KEY* const new_pk= (ha_alter_info->key_count > 0 &&
-                            is_candidate_key(ha_alter_info->key_info_buffer)) ?
+                            (!my_strcasecmp(system_charset_info,
+                                ha_alter_info->key_info_buffer->name,
+                                primary_key_name) ||
+                            is_candidate_key(ha_alter_info->key_info_buffer))) ?
                            ha_alter_info->key_info_buffer : NULL;
+  const KEY *const old_pk= table->s->primary_key == MAX_KEY ? NULL :
+                           table->key_info + table->s->primary_key;
 
   DBUG_PRINT("info", ("index count old: %d  new: %d",
                       table->s->keys, ha_alter_info->key_count));
@@ -6526,8 +6529,7 @@ static bool fill_alter_inplace_info(THD *thd,
       (i) Old table doesn't have primary key, new table has it and vice-versa
       (ii) Primary key changed to another existing index
     */
-    if ((new_key == new_pk) !=
-        ((uint) (table_key - table->key_info) == table->s->primary_key))
+    if ((new_key == new_pk) != (table_key == old_pk))
       goto index_changed;
 
     continue;
@@ -6581,22 +6583,6 @@ static bool fill_alter_inplace_info(THD *thd,
 
   /* Now let us calculate flags for storage engine API. */
 
-  /* Count all existing candidate keys. */
-  for (table_key= table->key_info; table_key < table_key_end; table_key++)
-  {
-    /*
-      Check if key is a candidate key, This key is either already primary key
-      or could be promoted to primary key if the original primary key is
-      dropped.
-      In MySQL one is allowed to create primary key with partial fields (i.e.
-      primary key which is not considered candidate). For simplicity we count
-      such key as a candidate key here.
-    */
-    if (((uint) (table_key - table->key_info) == table->s->primary_key) ||
-        is_candidate_key(table_key))
-      candidate_key_count++;
-  }
-
   /* Figure out what kind of indexes we are dropping. */
   KEY **dropped_key;
   KEY **dropped_key_end= ha_alter_info->index_drop_buffer +
@@ -6609,21 +6595,10 @@ static bool fill_alter_inplace_info(THD *thd,
 
     if (table_key->flags & HA_NOSAME)
     {
-      /*
-        Unique key. Check for PRIMARY KEY. Also see comment about primary
-        and candidate keys above.
-      */
-      if ((uint) (table_key - table->key_info) == table->s->primary_key)
-      {
+      if (table_key == old_pk)
         ha_alter_info->handler_flags|= Alter_inplace_info::DROP_PK_INDEX;
-        candidate_key_count--;
-      }
       else
-      {
         ha_alter_info->handler_flags|= Alter_inplace_info::DROP_UNIQUE_INDEX;
-        if (is_candidate_key(table_key))
-          candidate_key_count--;
-      }
     }
     else
       ha_alter_info->handler_flags|= Alter_inplace_info::DROP_INDEX;
@@ -6636,23 +6611,10 @@ static bool fill_alter_inplace_info(THD *thd,
 
     if (new_key->flags & HA_NOSAME)
     {
-      bool is_pk= !my_strcasecmp(system_charset_info, new_key->name, primary_key_name);
-
-      if ((!(new_key->flags & HA_KEY_HAS_PART_KEY_SEG) &&
-           !(new_key->flags & HA_NULL_PART_KEY)) ||
-          is_pk)
-      {
-        /* Candidate key or primary key! */
-        if (candidate_key_count == 0 || is_pk)
-          ha_alter_info->handler_flags|= Alter_inplace_info::ADD_PK_INDEX;
-        else
-          ha_alter_info->handler_flags|= Alter_inplace_info::ADD_UNIQUE_INDEX;
-        candidate_key_count++;
-      }
+      if (new_key == new_pk)
+        ha_alter_info->handler_flags|= Alter_inplace_info::ADD_PK_INDEX;
       else
-      {
         ha_alter_info->handler_flags|= Alter_inplace_info::ADD_UNIQUE_INDEX;
-      }
     }
     else
       ha_alter_info->handler_flags|= Alter_inplace_info::ADD_INDEX;