**Describe the bug**
Under certain conditions the equals comparison between String and Date yields the wrong result. Range Comparisons with greather-than-equals returns the correct result set.

**How to reproduce**
* Which ClickHouse server version to use: 21.2.5.5 (latest at the time of this issue)
* Which interface to use, if matters: HTTP (but should not matter)

```sql
CREATE TABLE default.myTable (
	myDay Date,
	myOrder Int32,
	someData String
) 
ENGINE = ReplacingMergeTree
PARTITION BY floor(toYYYYMMDD(myDay), -1)
ORDER BY (myOrder)
;

INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-01', 1);
INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-02', 2); // This row should be returned
INSERT INTO default.myTable (myDay, myOrder) VALUES ('2021-01-03', 3);

SELECT * FROM default.myTable mt
WHERE myDay = '2021-01-02';
```

**Expected behavior**
The last query in the example should yield the marked row. Instead it returns a empty result set.

There must be a connection to the used `PARTITION KEY`. The issue fails to reproduce as soon as I do any changes to the `PARTITION KEY` setting.

}
    };
    size_t left_args_count = 1;
    const auto * left_arg_tuple = left_arg->as<ASTFunction>();
    if (left_arg_tuple && left_arg_tuple->name == "tuple")
    {
        const auto & tuple_elements = left_arg_tuple->arguments->children;
        left_args_count = tuple_elements.size();
        for (size_t i = 0; i < left_args_count; ++i)
            get_key_tuple_position_mapping(tuple_elements[i], i);
    }
    else
        get_key_tuple_position_mapping(left_arg, 0);
    if (indexes_mapping.empty())
        return false;
    const ASTPtr & right_arg = args[1];
    SetPtr prepared_set;
    if (right_arg->as<ASTSubquery>() || right_arg->as<ASTIdentifier>())
    {
        auto set_it = prepared_sets.find(PreparedSetKey::forSubquery(*right_arg));
        if (set_it == prepared_sets.end())
            return false;
        prepared_set = set_it->second;
    }
    else
    {