121108 10:10:14 [Note] WSREP: NULL key skipped: INSERT INTO `user_other_info` VALUES (81219282,0x78696E78696E3033303340736F68752E636F6D ,'',0x30,0 x3133383130353039383830,0x31,'','','','',0x78696E7 8696E30333 0335F4E4557,0x32,0x33303031,0x33,0x313130303030,0x 3131303130 30,0x312C38,'','','
121108 10:10:15 [Note] WSREP: NULL key skipped: INSERT INTO `user_other_info` VALUES (81219282,0x78696E78696E3033303340736F68752E636F6D ,'',0x30,0 x3133383130353039383830,0x31,'','','','',0x78696E7 8696E30333 0335F4E4557,0x32,0x33303031,0x33,0x313130303030,0x 3131303130 30,0x312C38,'','','

it took me 7 days to load data with mysqldump backup (300G)

TEST

mysql> create table testnull1 (id int,userid varchar(20) null,primary key (id))engine innodb;
Query OK, 0 rows affected (0.00 sec)

mysql> create table testnull2 (id int,userid varchar(20) null,primary key (id),unique key uni_userid(userid))engine innodb;
Query OK, 0 rows affected (0.00 sec)

mysql> insert into testnull1 values(1,'u1');
Query OK, 1 row affected (0.00 sec)

mysql> insert into testnull1 values(2,null);
Query OK, 1 row affected (0.00 sec)

mysql> insert into testnull2 values(1,'u2');
Query OK, 1 row affected (0.00 sec)

mysql> insert into testnull2 values(2,null);
Query OK, 1 row affected (0.00 sec)

mysql> insert into testnull2 values(3,null);
Query OK, 1 row affected (0.00 sec)

mysql> insert into testnull1 values(3,null);
Query OK, 1 row affected (0.00 sec)

mysql> select * from testnull1;
+----+--------+
| id | userid |
+----+--------+
| 1 | u1 |
| 2 | NULL |
| 3 | NULL |
+----+--------+
3 rows in set (0.00 sec)

mysql> select * from testnull2;
+----+--------+
| id | userid |
+----+--------+
| 2 | NULL |
| 3 | NULL |
| 1 | u2 |
+----+--------+
3 rows in set (0.00 sec)


LOG:

121108 17:05:21 [Note] WSREP: TO BEGIN: 4, 0 : create table testnull1 (id int,userid varchar(20) null,primary key (id))engine innodb
121108 17:05:21 [Note] WSREP: TO BEGIN: 5, 2
121108 17:05:21 [Note] WSREP: avoiding binlog rotate due to TO isolation: 1
121108 17:05:21 [Note] WSREP: TO END: 5, 2 : create table testnull1 (id int,userid varchar(20) null,primary key (id))engine innodb
121108 17:05:21 [Note] WSREP: TO END: 5
121108 17:05:52 [Note] WSREP: TO BEGIN: 5, 0 : create table testnull2 (id int,userid varchar(20) null,primary key (id),unique key uni_userid(userid))engine innodb
121108 17:05:52 [Note] WSREP: TO BEGIN: 6, 2
121108 17:05:52 [Note] WSREP: avoiding binlog rotate due to TO isolation: 1
121108 17:05:52 [Note] WSREP: TO END: 6, 2 : create table testnull2 (id int,userid varchar(20) null,primary key (id),unique key uni_userid(userid))engine innodb
121108 17:05:52 [Note] WSREP: TO END: 6
121108 17:06:38 [Note] WSREP: NULL key skipped: insert into testnull2 values(2,null)
121108 17:06:52 [Note] WSREP: NULL key skipped: insert into testnull2 values(3,null)