Bug Report

What version of TiKV are you using?

master

What operating system and CPU are you using?

not system related bug

Steps to reproduce

1. start a cluster with pd, tidb and tikv
2. execute the following queries

CREATE TABLE t1 (c VARCHAR(4) CHARACTER SET gbk);
INSERT INTO t1 VALUES (0x8BF5819AEDC3); --'嬽仛砻', or others like (0x90459958) '怑橷'
SELECT ANY_VALUE(HEX(c)), COUNT(c) FROM t1 GROUP BY c COLLATE gbk_chinese_ci;
-- or SELECT ANY_VALUE(HEX(c)), COUNT(c) FROM t1 GROUP BY c COLLATE gbk_bin;

What did you expect?

All statements succeed to execute (mysql-server and tidb with unistore can execute)

What did happened?

Encounter (1105, 'encoding failed') for last statement