I think this is a bug in MySQL 5.1.16-beta (I'm using SUSE 10.2 Linux), but I can't find any information on it.
When performing an update which doesn't change any rows, I get different results back depending on the declarations of the fields in the table. If a 'normal' NDB table is created and an inserted row is updated: mysql> CREATE TABLE table1 (field1 int(11), field2 int(11)) engine ndb; Query OK, 0 rows affected (1.17 sec) mysql> insert into table1 values (1,2); Query OK, 1 row affected (0.04 sec) mysql> update table1 set field2=3 where field1=1; -- This should return one changed row Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> update table1 set field2=3 where field1=1; -- The same update should return 0 rows Query OK, 0 rows affected (0.00 sec) Rows matched: 1 Changed: 0 Warnings: 0 The second update is 'changing' the record to the same value currently in the database, so it returns 0 records changed. However, if the table is changed so that field1 is a primary key, the number of rows changed is different: mysql> CREATE TABLE table2 (field1 int(11) primary key, field2 int(11)) engine ndb; Query OK, 0 rows affected (4.18 sec) mysql> insert into table2 values (1,2); Query OK, 1 row affected (0.00 sec) mysql> update table2 set field2=3 where field1=1; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> update table2 set field2=3 where field1=1; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 Here the second update reports 1 row has changed, even though the data is the same. This doesn't happen in MySQL 5.1.11 on the same machine. In both cases I'm running a single node cluster on one box (I know that's a bit pointless but it's meant to be a proof of concept :-)). I tried the same tests using InnoDB and got 1 Changed row in each case, and with MyISAM I got 0 rows changed. Can anyone confirm if they have the same problem or if it's something I've done wrong? Brian
