Method executeTuple

src/Functions/array/arrayElement.cpp:676–726

}

ColumnPtr FunctionArrayElement::executeTuple(const ColumnsWithTypeAndName & arguments, size_t input_rows_count) const
{
    const ColumnArray * col_array = typeid_cast<const ColumnArray *>(arguments[0].column.get());

    if (!col_array)
        return nullptr;

    const ColumnTuple * col_nested = typeid_cast<const ColumnTuple *>(&col_array->getData());

    if (!col_nested)
        return nullptr;

    if (is_mysql_dialect)
        throw Exception(ErrorCodes::NOT_IMPLEMENTED, "arrayElement(col, idx) where col is Array(Tuple(T)) is not supported under MySQL.");

    const auto & tuple_columns = col_nested->getColumns();
    size_t tuple_size = tuple_columns.size();

    const DataTypes & tuple_types = typeid_cast<const DataTypeTuple &>(
        *typeid_cast<const DataTypeArray &>(*arguments[0].type).getNestedType()).getElements();

    /** We will calculate the function for the tuple of the internals of the array.
      * To do this, create a temporary columns.
      * It will consist of the following columns
      * - the index of the array to be taken;
      * - an array of the first elements of the tuples;
      * - the result of taking the elements by the index for an array of the first elements of the tuples;
      * - array of the second elements of the tuples;
      * - result of taking elements by index for an array of second elements of tuples;
      * ...
      */
    ColumnsWithTypeAndName temporary_results(2);
    temporary_results[1] = arguments[1];

    /// results of taking elements by index for arrays from each element of the tuples;
    Columns result_tuple_columns(tuple_size);

    for (size_t i = 0; i < tuple_size; ++i)
    {
        ColumnWithTypeAndName array_of_tuple_section;
        array_of_tuple_section.column = ColumnArray::create(tuple_columns[i], col_array->getOffsetsPtr());
        array_of_tuple_section.type = std::make_shared<DataTypeArray>(tuple_types[i]);
        temporary_results[0] = array_of_tuple_section;

        auto type = getReturnTypeImpl(temporary_results);
        auto col = executeImpl(temporary_results, type, input_rows_count);
        result_tuple_columns[i] = std::move(col);
    }

    return ColumnTuple::create(result_tuple_columns);
}

namespace
{