vreplication: can not replicate char column with binary collate

[tokikanno]

Overview of the Issue

Due to #7969, fixed length char column with binary collate will not be able to be replicated because the extra padding bytes.

Reproduction Steps

• Create a table like below

CREATE TABLE `chrome_subscription` (
  `beacon` varchar(64) COLLATE utf8mb4_bin NOT NULL DEFAULT '',
  `locale` char(5) COLLATE utf8mb4_bin DEFAULT NULL,
  `currency` char(3) COLLATE utf8mb4_bin DEFAULT NULL,
  `geo` char(3) COLLATE utf8mb4_bin DEFAULT NULL,
  `city` char(3) COLLATE utf8mb4_bin DEFAULT NULL,
  `created` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
  `modified` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`beacon`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin

• Add some rows
• Put this table into MoveTables workflow
• Modify some rows while workflow in copy state
• Extra paddings will be added to all the char columns of the the vreplication data and make the update SQL failed like below

E0830 22:06:41.975815       1 dbclient.go:107] error in stream 11, retrying after 5s: Data too long for column 'locale' at row 1 (errno 1406) (sqlstate 22001) during query: update chrome_subscription set locale='ja\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0', currency='TWD\0\0\0\0\0\0\0\0\0', geo='TW\0\0\0\0\0\0\0\0\0\0', city='TPE\0\0\0\0\0\0\0\0\0', created='2021-08-14 08:51:26' where beacon='202107232XaefvbpM4'

Plz also see:

• test case ( #8730 ) added by @mattlord
• slack discussion ( https://vitess.slack.com/archives/CMKTCUYNQ/p1630315305015400 )

Binary version

v11.0.0

[mattlord]

This was resolved via https://github.com/vitessio/vitess/pull/8730

Thank you @tokikanno!