After decoding that BINLOG'...' to discover 20 bytes for a column declared as
`a_field` varchar(20) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL DEFAULT ' ', I can only think of
that BINLOG'...' was created against a different column definition, one that would clearly lack utf8 charset.

Per direct verification 10.2.15 in particular creates BINLOG for the field with the value of 60 for its length, therefore
no conversion issue would happen, in contrast to the claim.

sujatha.sivakumar,
I think the case would be easier to understand and to resolve should we have the following
bugfixes cherry-picked from the upstream. I am resigning for your favor to implement that.
Thanks!

commit 47bd3f7cf3c8518f62b1580ec65af2ba7ac13b95
Author: Sujatha Sivakumar <sujatha.sivakumar@oracle.com>
Date: Fri Feb 24 10:53:23 2017 +0530

Bug#25135304: RBR: WRONG FIELD LENGTH IN ERROR MESSAGE

Description:
============
In row based replication, when replicating from a table with
a field with character set set to UTF8mb3 to the same table
with the same field set to character set UTF8mb4 I get a
confusing error message:

Cherry-pick is in progress.

This will fix confusing error messages like shown below.

Case 1:
======

--source include/master-slave.inc

--source include/have_binlog_format_row.inc

SET SQL_LOG_BIN=0;

CREATE TABLE t1 (c1 VARCHAR(1) CHARACTER SET 'utf8mb3');

SET SQL_LOG_BIN=1;

--source include/rpl_connection_slave.inc

SET SQL_LOG_BIN=0;

CREATE TABLE t1 (c1 VARCHAR(1) CHARACTER SET 'utf8mb4');

SET SQL_LOG_BIN=1;

--source include/rpl_connection_master.inc

INSERT INTO t1 VALUES ('a');

DROP TABLE t1;

--source include/sync_slave_sql_with_master.inc

--source include/rpl_end.inc

2. Run the test case:

perl mysql-test-run.pl --mem rpl_x.test

3. Watch the test fail and look at the error message:

[...]
Last_Error Column 0 of table 'test.t1' cannot be converted from type 'varchar(3)' to type 'varchar(1)'
[...]

Case 2:
======

--connection master

SET SQL_LOG_BIN=0;

CREATE TABLE t1 (c1 CHAR(1) CHARACTER SET 'utf8mb3');

SET SQL_LOG_BIN=1;

--connection slave

CREATE TABLE t1 (c1 CHAR(1) CHARACTER SET 'utf8mb4');

--connection master

INSERT INTO t1 VALUES ('a');

--connection slave

--let $slave_sql_errno= 1677

--source include/wait_for_slave_sql_error.inc

1. Error msg before: Column 0 of table 'test.t1' cannot be converted from type 'char(0)' to type 'char(1)'
2. Error msg after : Column 0 of table 'test.t1' cannot be converted from type 'char(3(bytes))' to type 'char(4(bytes) utf8mb4)'

Case 3:
======

--connection master

SET SQL_LOG_BIN=0;

CREATE TABLE t1 (c1 LONGBLOB);

SET SQL_LOG_BIN=1;

--connection slave

CREATE TABLE t1 (c1 TINYBLOB);

--connection master

INSERT INTO t1 VALUES ('a');

--connection slave

--let $slave_sql_errno= 1677

--source include/wait_for_slave_sql_error.inc

1. Error msg before: Column 0 of table 'test.t1' cannot be converted from type 'tinyblob' to type 'tinyblob'
2. Error msg after : Column 0 of table 'test.t1' cannot be converted from type 'longblob' to type 'tinyblob'

Hello Andrei,

Please review the fixes for MDEV-19925.

There is a small change in the patch apart from the cherry-pick.
I adapted the tests as per MariaDB- 10.2. Fixed test result failures.
Please find the following additional changes in code apart from the
cherry-pick.

sql/rpl_utility.cc

+ (field->real_type() != MYSQL_TYPE_ENUM &&
+ field->real_type() != MYSQL_TYPE_SET) &&

Patch has been tested in build bot.
BB link: http://buildbot.askmonty.org/buildbot/grid?category=main&branch=bb-10.2-sujatha
Patch: https://github.com/MariaDB/server/commit/6aa04bcdd94da4dee23df48c7c53d8a0082a415f

Thank you.

Hi Sujatha,

The patch
https://github.com/MariaDB/server/commit/88945a168f679239cca2e597235e731ccc778999
looks ok to push for me.

Thanks!

Fix for this issue is implemented in 10.2.27.
Fix has been tested on higher versions.

Please find
Patches for 10.3: https://github.com/MariaDB/server/commit/f5bed83a42f616e297380c8bcc2379316fe4d0d8

10.4 changes: https://github.com/MariaDB/server/commit/dc0f2438b8d71ef6301f43009a0c8de54a8e945f