If they are defined, they can override table-level settings.
throw Exception(ErrorCodes::INVALID_PARTITION_VALUE,
                        "Wrong number of fields in the partition expression: {}, must be: {}",
                        partition_ast.fields_count, fields_count);
    Row partition_row(fields_count);
    if (fields_count == 0)
    {
        /
        assert(!partition_ast.fields_count);
        assert(typeid_cast<ASTFunction *>(partition_ast.value.get()));
        assert(partition_ast.value->as<ASTFunction>()->name == "tuple");
        assert(partition_ast.value->as<ASTFunction>()->arguments);
        bool empty_tuple = partition_ast.value->as<ASTFunction>()->arguments->children.empty();
        if (!empty_tuple)
            throw Exception(ErrorCodes::INVALID_PARTITION_VALUE, "Partition key is empty, expected 'tuple()' as partition key");
    }
    else if (fields_count == 1)
    {
        ASTPtr partition_value_ast = partition_ast.value;
        if (auto * tuple = partition_value_ast->as<ASTFunction>())
        {
            assert(tuple->name == "tuple");
            assert(tuple->arguments);
            assert(tuple->arguments->children.size() == 1);
            partition_value_ast = tuple->arguments->children[0];
        }
        /
        Field partition_key_value = evaluateConstantExpression(partition_value_ast, local_context).first;
        partition_row[0] = convertFieldToTypeOrThrow(partition_key_value, *key_sample_block.getByPosition(0).type);
    }
    else