json comparison is not compatible with MySQL after push down

[YangKeao]

Enhancement

create table t(i INT, j JSON);
insert into t values(0, '{"a":1}');
insert into t values(1, '{"b":1}');
insert into t values(2, '1');
insert into t values(3, '2');
insert into t values(4, '3');
insert into t values(5, '100');
insert into t values(6, 'true');
insert into t values(7, '[1, 2, 3, 4]');
insert into t values(8, '[1, 2, 3]');
insert into t values(9, '[5]');
insert into t values(10, '3.14');
insert into t values(11, '6.28');
insert into t values(12, '"string a"');
insert into t values(13, '"string a b"');
insert into t values(14, '"string b"');
insert into t values(15, cast(X'ABCD' as JSON));
insert into t values(16, cast(X'BACD' as JSON));
insert into t values(17, cast(X'ABCDE0' as JSON));

select i from t where j > cast(TRUE as json);

With TiKV pushdown, it gives 3,4,5,10,11,15,16,17. But with TiDB (#37404) and MySQL 5.7, it gives 15,16,17.