Here is my review comments:
+++ ./003_mariadb-10.2.0-vp/sql/ha_partition.cc 2016-05-05 21:25:04.289731712 +0900
@@ -7238,13 +7239,30 @@ int ha_partition::extra(enum ha_extra_fu
}
/* Category 9) Operations only used by MERGE */
case HA_EXTRA_ADD_CHILDREN_LIST:
+ DBUG_RETURN(loop_extra(operation));
case HA_EXTRA_ATTACH_CHILDREN:
+ int result;
+ handler **file;
+ if ((result = loop_extra(operation)))
+ DBUG_RETURN(result);
+ m_num_locks = 0;
+ additional_table_flags =
+ (HA_CAN_BG_SEARCH | HA_CAN_BG_INSERT | HA_CAN_BG_UPDATE);
+ file = m_file;
+ do
+ {
+ m_num_locks += (*file)->lock_count();
+ additional_table_flags &= ~((ulonglong) ((*file)->ha_table_flags() ^
+ (HA_CAN_BG_SEARCH | HA_CAN_BG_INSERT | HA_CAN_BG_UPDATE)));

The above test could be simple:

additional_table_flags &= (ulonglong) ((*file)->ha_table_flags();

Should be the same thing.

I also changed so that m_num_locks always contains the upper limit
number of locks needed. Without this change, the call to lock_count() would
have returneed m_total_parts * 'new-counted-locks' which would be been
way too much.

@@ -9123,6 +9141,19 @@ const COND *ha_partition::cond_push(cons
handler **file= m_file;
COND *res_cond = NULL;
DBUG_ENTER("ha_partition::cond_push");
+#ifdef HANDLER_HAS_TOP_TABLE_FIELDS
+ if (set_top_table_fields)
+ {
+ do
+

while (*(++file));
+ file= m_file;
+ }
+#endif

I added this without the define, but I merged it to the loop for cond_push.

Instead of having defines in the sql code, I will fix that in spider and vp
that I will set the proper defines based on the MariaDB version.

However, I would like to have a clear comment the purpose of the function
set_top_table_and_fields().

struct st_mysql_storage_engine partition_storage_engine=

;

+++ ./003_mariadb-10.2.0-vp/sql/handler.h 2016-05-05 21:25:04.314731713 +0900
@@ -255,6 +257,11 @@ enum enum_alter_inplace_result {
*/
#define HA_BINLOG_FLAGS (HA_BINLOG_ROW_CAPABLE | HA_BINLOG_STMT_CAPABLE)

+#define HA_CAN_BG_SEARCH (1LL << 45)
+#define HA_CAN_BG_INSERT (1LL << 46)
+#define HA_CAN_BG_UPDATE (1LL << 47)
+#define HA_CAN_MULTISTEP_MERGE (1LL << 48)

Do you really need HA_CAN_BG_XXX flags?
I checked your spider tree and this is not used anywhere, so I think we should leave them out for now.
If we don't need these, we can remove the loop for setting them in
HA_EXTRA_ATTACH_CHILDREN too.

If we need them, I would like to have a comment for why they are needed and
when we will need then add these in a separate patch.

@@ -3525,6 +3540,29 @@ public:
Pops the top if condition stack, if stack is not empty.
*/
virtual void cond_pop()

;
+ virtual int set_top_table_and_fields(TABLE *top_table,
+ Field **top_table_field,
+ uint top_table_fields)
+ {
+ if (!set_top_table_fields)
+

+ return 0;
+ }

Why is this int and not void ?
Do you have in mind that this may be possible to fail in the future?
If it's never going to change, then better to do this void.

I will make it void for now and change the relevant code. We can make it
int again if needed in the future.

diff -Narup ./002_mariadb-10.2.0-spider/sql/sql_base.cc ./003_mariadb-10.2.0-vp/sql/sql_base.cc
— ./002_mariadb-10.2.0-spider/sql/sql_base.cc 2016-04-17 02:47:27.000000000 +0900
+++ ./003_mariadb-10.2.0-vp/sql/sql_base.cc 2016-05-05 21:25:04.319731713 +0900
@@ -1475,6 +1475,10 @@ unique_table(THD *thd, TABLE_LIST *table

table= table->find_table_for_update();

• if (table->table && table->table->file->ht->db_type == DB_TYPE_MRG_MYISAM)
• {
• TABLE_LIST *child;
  + if (table->table &&
  + (
  + table->table->file->ht->db_type == DB_TYPE_MRG_MYISAM ||
  + (table->table->file->ha_table_flags() & HA_CAN_MULTISTEP_MERGE)
  + )
  + )
  + continue

I added HA_CAN_MULTISTEP_MERGE as a flag to DB_TYPE_MRG_MYISAM, which
allwoed me to make the above tests and the following identical ones much
simpler.

Please comment on my email or issue comment or close review.
The code is already pushed into 10.2-spider, but can be changed if there is anything you more that you require.

Got review from Kentoku and have applied the required changes