void AggregatingSortedBlockInputStream::merge(MutableColumns & merged_columns, std::priority_queue<SortCursor> & queue)
{
size_t merged_rows = 0;
/// We take the rows in the correct order and put them in `merged_block`, while the rows are no more than `max_block_size`
while (!queue.empty())
{
SortCursor current = queue.top();
setPrimaryKeyRef(next_key, current);
bool key_differs;
if (current_key.empty()) /// The first key encountered.
{
setPrimaryKeyRef(current_key, current);
key_differs = true;
}
else
key_differs = next_key != current_key;
/// if there are enough rows accumulated and the last one is calculated completely
if (key_differs && merged_rows >= max_block_size)
return;
queue.pop();
if (key_differs)
{
current_key.swap(next_key);
/// We will write the data for the group. We copy the values of ordinary columns.
for (size_t i = 0, size = column_numbers_not_to_aggregate.size(); i < size; ++i)
{
size_t j = column_numbers_not_to_aggregate[i];
merged_columns[j]->insertFrom(*current->all_columns[j], current->pos);
}
/// Add the empty aggregation state to the aggregate columns. The state will be updated in the `addRow` function.
for (auto & column_to_aggregate : columns_to_aggregate)
column_to_aggregate->insertDefault();
++merged_rows;
}
addRow(current);
if (!current->isLast())
{
current->next();
queue.push(current);
}
else
{
/// We fetch the next block from the appropriate source, if there is one.
fetchNextBlock(current, queue);
}
}
finished = true;
}
void AggregatingSortedBlockInputStream::merge(ColumnPlainPtrs & merged_columns, std::priority_queue<TSortCursor> & queue)
{
size_t merged_rows = 0;
/// Вынимаем строки в нужном порядке и кладём в merged_block, пока строк не больше max_block_size
while (!queue.empty())
{
TSortCursor current = queue.top();
setPrimaryKeyRef(next_key, current);
bool key_differs;
if (current_key.empty()) /// Первый встретившийся ключ.
{
current_key.columns.resize(description.size());
setPrimaryKeyRef(current_key, current);
key_differs = true;
}
else
key_differs = next_key != current_key;
/// если накопилось достаточно строк и последняя посчитана полностью
if (key_differs && merged_rows >= max_block_size)
return;
queue.pop();
if (key_differs)
{
current_key.swap(next_key);
/// Запишем данные для очередной группы. Копируем значения обычных столбцов.
for (size_t i = 0, size = column_numbers_not_to_aggregate.size(); i < size; ++i)
{
size_t j = column_numbers_not_to_aggregate[i];
merged_columns[j]->insertFrom(*current->all_columns[j], current->pos);
}
/// Добавляем в агрегатные столбцы пустое состояние агрегации. Состояние будет обновлено в функции addRow.
for (auto & column_to_aggregate : columns_to_aggregate)
column_to_aggregate->insertDefault();
++merged_rows;
}
addRow(current);
if (!current->isLast())
{
current->next();
queue.push(current);
}
else
{
/// Достаём из соответствующего источника следующий блок, если есть.
fetchNextBlock(current, queue);
}
}
finished = true;
}
