Всем привет,
есть таблица со строковым уникальным полем:


[/SRC]
Есть другая таблица


И я создаю таблицу многие к многим этих таблиц :



при выполнении последнего запроса я получаю ошибку :
авторERROR: Can't create table 'roc_new_version.inventory_item_paperwork'
(errno: 150)
Error Code: 1005


Через команду SHOW INNODB STATUS я прочитал :
автор=====================================
130811 14:02:40 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 0 seconds
----------
SEMAPHORES
----------
OS WAIT ARRAY INFO: reservation count 606, signal count 603
Mutex spin waits 0, rounds 8541, OS waits 97
RW-shared spins 342, OS waits 157; RW-excl spins 414, OS waits 342
------------------------
LATEST FOREIGN KEY ERROR
------------------------
130811 14:01:26 Error in foreign key constraint of table roc_new_version/inventory_item_paperwork:

FOREIGN KEY (`sku`)
REFERENCES `inventory_item` (`sku`)
ON DELETE RESTRICT,
CONSTRAINT `inventory_item_paperwork_FK_2`
FOREIGN KEY (`paperwork_id`)
REFERENCES `paperwork` (`id`)
ON DELETE RESTRICT
)Type=InnoDB:
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.1/en/innodb-foreign-key-constraints.html
for correct foreign key definition.
------------
TRANSACTIONS
------------
Trx id counter 0 2131673
Purge done for trx's n:o < 0 2131553 undo n:o < 0 0
History list length 13
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 0 2131583, not started, process no 5056, OS thread id 3009514352
MySQL thread id 2, query id 2969 localhost 127.0.0.1 root
SHOW INNODB STATUS
--------
FILE I/O
--------
I/O thread 0 state: waiting for i/o request (insert buffer thread)
I/O thread 1 state: waiting for i/o request (log thread)
I/O thread 2 state: waiting for i/o request (read thread)
I/O thread 3 state: waiting for i/o request (write thread)
Pending normal aio reads: 0, aio writes: 0,
ibuf aio reads: 0, log i/o's: 0, sync i/o's: 0
Pending flushes (fsync) log: 0; buffer pool: 0
10535 OS file reads, 7917 OS file writes, 1294 OS fsyncs
0.00 reads/s, 0 avg bytes/read, 0.00 writes/s, 0.00 fsyncs/s
-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 5, seg size 7,
35538 inserts, 35538 merged recs, 1000 merges
Hash table size 34679, node heap has 1 buffer(s)
0.00 hash searches/s, 0.00 non-hash searches/s
---
LOG
---
Log sequence number 0 965814754
Log flushed up to 0 965814754
Last checkpoint at 0 965814754
0 pending log writes, 0 pending chkp writes
1179 log i/o's done, 0.00 log i/o's/second
----------------------
BUFFER POOL AND MEMORY
----------------------
Total memory allocated 19783690; in additional pool allocated 1048576
Dictionary memory allocated 1891784
Buffer pool size 512
Free buffers 0
Database pages 511
Modified db pages 0
Pending reads 0
Pending writes: LRU 0, flush list 0, single page 0
Pages read 13938, created 8600, written 14849
0.00 reads/s, 0.00 creates/s, 0.00 writes/s
No buffer pool page gets since the last printout
--------------
ROW OPERATIONS
--------------
0 queries inside InnoDB, 0 queries in queue
1 read views open inside InnoDB
Main thread process no. 5056, id 2971933552, state: waiting for server activity
Number of rows inserted 163019, updated 4, deleted 0, read 811932
0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 0.00 reads/s
----------------------------
END OF INNODB MONITOR OUTPUT
============================

не пойму какого идекса не хватает ?

Спасибо !