REFERRED BY A STATEMENT

Description:

WL#7957 lists following as a future enhancement.
...
F-10
When defining partitioned tables, assigning explicit tablespace
names is not supported for the individual partitions. However,
with the implementation of SE native partitioning (e.g. WL#6035
for InnoDB), this will mean that the various DDL statements need
to take more than one tablespace into account.  Thus, in the
future, this will affect F-3 above, but for now, in the context
of this worklog, this is deferred.
...

WL#6035 is pushed and we support more than one tablespace
(explicit tablespace per partition) in various DDL statements,
and the problem is we do not take MDL locks on all tablespaces in
use.

Solution:
Acquire IX MDL lock on tablespace names used by partition and
sub-partition definitions along with tablespace name used by
table. We do that in following cases,

1. Lock only the target tablespace name and tablespace
   names that are used by partitions (e.g. CREATE TABLE
   explicitly specifying the tablespace names).

2. Lock only the existing tablespace name and tablespace
   names that are used by partitions (e.g. ALTER TABLE t
   ADD COLUMN ... where t is defined in some tablespace s.

3. Lock both the target and the existing tablespace names
   along with tablespace names used by partitions. (e.g.
   ALTER TABLE t TABLESPACE s2, where t is defined in
   some tablespace s)

4. Lock on tablespace names used by new partitions that are
   added by following command,

    => ALTER TABLE <table_name>
         ADD PARTITION
           (PARTITION .. TABLESPACE <tablespace_name>);

   Currently lock_table_names() does try and lock partition
   tablespace names that are part of thd->work_part_info as
   Phase 4$ invoking check_and_lock_tablespace_names().
   During ALTER TABLE we currently set thd->work_part_info
   with new partition information bit late after the
   lock_table_names() is done. The fix is to make new
   partition information available in thd->work_part_info
   before we request MDL locks.

5. Lock on tablespace names for the source table and source table
   partitions, in case of CREATE TABLE LIKE.

Tablespace names used by partitions are retrieved by parsing
the partition expression stored in .FRM. This applies even for
for NDB tables with partitions before mysql version 50120.