the results of ord function pushed down to tikv is different with tidb

[ChenPeng2013]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

tiup deploy a cluster

use test;
drop table if exists PK_TCOLLATION10116;
CREATE TABLE `PK_TCOLLATION10116` (   `COL1` char(1) COLLATE utf8_general_ci NOT NULL,   `COL2` varchar(20) COLLATE utf8_general_ci DEFAULT NULL,   `COL4` datetime DEFAULT NULL,   `COL3` bigint(20) DEFAULT NULL,   `COL5` float DEFAULT NULL,   PRIMARY KEY (`COL1`) /*T![clustered_index] CLUSTERED */ ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci;
insert into PK_TCOLLATION10116(col1) values("鷳");

select col1, ord(col1) from PK_TCOLLATION10116 where ord(col1)=ord("鷳");
insert into mysql.expr_pushdown_blacklist(name) values('ord');
admin reload expr_pushdown_blacklist;
select col1, ord(col1) from PK_TCOLLATION10116 where ord(col1)=ord("鷳");

2. What did you expect to see? (Required)

MySQL [test]>  select col1, ord(col1) from PK_TCOLLATION10116 where ord(col1)=ord("鷳");
+------+-----------+
| col1 | ord(col1) |
+------+-----------+
| 鷳  |  15316915 |
+------+-----------+
1 row in set (0.01 sec)

MySQL [test]>
MySQL [test]> insert into mysql.expr_pushdown_blacklist(name) values('ord');
Query OK, 1 row affected (0.01 sec)

MySQL [test]> admin reload expr_pushdown_blacklist;
Query OK, 0 rows affected (0.01 sec)

MySQL [test]>  select col1, ord(col1) from PK_TCOLLATION10116 where ord(col1)=ord("鷳");;
+------+-----------+
| col1 | ord(col1) |
+------+-----------+
| 鷳  |  15316915 |
+------+-----------+
1 row in set (0.01 sec)

3. What did you see instead (Required)

MySQL [test]>  select col1, ord(col1) from PK_TCOLLATION10116 where ord(col1)=ord("鷳");
Empty set (0.01 sec)

MySQL [test]>
MySQL [test]> insert into mysql.expr_pushdown_blacklist(name) values('ord');
Query OK, 1 row affected (0.01 sec)

MySQL [test]> admin reload expr_pushdown_blacklist;
Query OK, 0 rows affected (0.01 sec)

MySQL [test]>  select col1, ord(col1) from PK_TCOLLATION10116 where ord(col1)=ord("鷳");;
+------+-----------+
| col1 | ord(col1) |
+------+-----------+
| 鷳  |  15316915 |
+------+-----------+
1 row in set (0.01 sec)

4. What is your TiDB version? (Required)

Release Version: v6.1.0-alpha
Edition: Community
Git Commit Hash: 6d01855856aac61e0829f73ed8a47be6add45321
Git Branch: heads/refs/tags/v6.1.0-alpha
UTC Build Time: 2022-03-23 14:59:02
GoVersion: go1.18
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false