Always reproduced:

```
milovidov-desktop :) create table table_map (a Map(String, String), b String) engine = MergeTree() order by a;

CREATE TABLE table_map
(
    `a` Map(String, String),
    `b` String
)
ENGINE = MergeTree
ORDER BY a

Query id: 8f8120c1-c165-452a-815f-2bcae3957e2a

Ok.

0 rows in set. Elapsed: 0.002 sec. 

milovidov-desktop :) SELECT b FROM table_map WHERE a = map('name', NULL, '', NULL)

SELECT b
FROM table_map
WHERE a = {'name', NULL, '', NULL}
```
static IFunction::Monotonicity get(const IDataType & type, const Field &, const Field &)
    {
        if (type.isValueRepresentedByNumber())
            return {true, true, true};
        else
            return {};
    }
};
/** The monotonicity for the `toString` function is mainly determined for test purposes.
  * It is doubtful that anyone is looking to optimize queries with conditions `toString(CounterID) = 34`.
  */
struct ToStringMonotonicity
{
    static bool has() { return true; }
    static IFunction::Monotonicity get(const IDataType & type, const Field & left, const Field & right)
    {
        IFunction::Monotonicity positive(true, true);
        IFunction::Monotonicity not_monotonic;
        const auto * type_ptr = &type;
        if (const auto * low_cardinality_type = checkAndGetDataType<DataTypeLowCardinality>(type_ptr))
            type_ptr = low_cardinality_type->getDictionaryType().get();
        
        if (checkDataTypes<DataTypeDate, DataTypeDateTime, DataTypeString>(type_ptr))
            return positive;
        if (left.isNull() || right.isNull())
            return {};
        if (left.getType() == Field::Types::UInt64
            && right.getType() == Field::Types::UInt64)
        {