Batch updates can cause data loss when downstream is MySQL.

[asddongmen]

What did you do?

After enabling batch DML feature, when converting update statements, TiCDC will transform the statements into the following format:

from:

CREATE TABLE t0 ( id INT not null, name varchar(128) CHARACTER SET gbk not null, country char(32) CHARACTER SET gbk, city varchar(64), description  text CHARACTER SET gbk, image tinyblob, UNIQUE
KEY (id, name) ) ENGINE = Innodb;

UPDATE t0
SET name = '开发'
WHERE name = '测试';

covert to:

"UPDATE `test`.`t0` SET `id`=CASE WHEN ROW(`id`,`name`)=ROW(?,?) THEN ? END, `name`=CASE WHEN ROW(`id`,`name`)=ROW(?,?) THEN ? END, `country`=CASE WHEN ROW(`id`,`name`)=ROW(?,?) THEN ? END, `city`=CASE WHEN ROW(`id`,`name`)=ROW(?,?) THEN ? END, `description`=CASE WHEN ROW(`id`,`name`)=ROW(?,?) THEN ? END, `image`=CASE WHEN ROW(`id`,`name`)=ROW(?,?) THEN ? END WHERE ROW(`id`,`name`) IN (ROW(?,?))\"]"] [values="[[1,\"测试\",1,1,\"测试\",\"开发\",1,\"测试\",\"中国\",1,\"测试\",\"上海\",1,\"测试\",\"你好,世界\",1,\"测试\",\"xOO6w8rAvec=\",1,\"测试\"]]"

The behavior of this statement differs between TiDB and MySQL. However, all downstream integration tests of TiCDC currently use TiDB, so relevant issues were not previously detected.

What did you expect to see?

No response

What did you see instead?

.

Versions of the cluster

Upstream TiDB cluster version (execute SELECT tidb_version(); in a MySQL client):

(paste TiDB cluster version here)

Upstream TiKV version (execute tikv-server --version):

(paste TiKV version here)

TiCDC version (execute cdc version):

(paste TiCDC version here)