Comment 2 for bug 1268632

This bug can be reproduced in Percona Server and MySQL as well. This bug is triggered when pt-table-sync is used to sync two separate MySQL servers where the target server is using STATEMENT as binary log format. The problem is, as per http://dev.mysql.com/doc/refman/5.5/en/replication-features-limit.html , UPDATE-LIMIT without ORDER BY is not replication safe.

Test case:

Server h1
use test;
create table t1(a int not null primary key, b int not null) engine=innodb;
insert into t1 values (0,0),(1,1),(2,2),(3,3);

Server h2
use test;
create table t1(a int not null primary key, b int not null) engine=innodb;
insert into t1 values (0,0),(1,1),(2,2),(3,4);

Note: binary log must be enabled on h2 and binary log format is STATEMENT

pt-table-sync --execute h=h1 h=h2

Warning:
141111 13:34:57 [Warning] Unsafe statement written to the binary log using statement format since BINLOG_FORMAT = STATEMENT. The statement is unsafe because it uses a LIMIT clause. This is unsafe because the set of rows included cannot be predicted. Statement: UPDATE `test`.`t1` SET `b`='3' WHERE `a`='3' LIMIT 1 /*percona-toolkit src_db:test src_tbl:t1 src_dsn:P=24394,h=127.0.0.1 dst_db:test dst_tbl:t1 dst_dsn:P=24395,h=127.0.0.1 lock:0 transaction:1 changing_src:0 replicate:0 bidirectional:0 pid:3553 user:user host:localhost.localdomain*/