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Using SortingHeap in MergingSortedTransform

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This commit is contained in:
Alexey Milovidov 2019-12-22 17:22:42 +03:00
parent 906bfdbaa7
commit 8613b90d84
3 changed files with 62 additions and 84 deletions
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7
dbms/src/Core/SortCursor.h
View File

@ -281,6 +281,13 @@ public:
queue.pop_back();
}
void push(SortCursorImpl & cursor)
{
queue.emplace_back(&cursor);
std::push_heap(queue.begin(), queue.end());
next_idx = 0;
}
private:
using Container = std::vector<Cursor>;
Container queue;

56
dbms/src/Processors/Transforms/MergingSortedTransform.cpp
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@ -145,9 +145,9 @@ IProcessor::Status MergingSortedTransform::prepare()
return Status::NeedData;
if (has_collation)
initQueue(queue_with_collation);
queue_with_collation = SortingHeap<SortCursorWithCollation>(cursors);
else
initQueue(queue_without_collation);
queue_without_collation = SortingHeap<SortCursor>(cursors);
is_initialized = true;
return Status::Ready;
@ -166,7 +166,6 @@ IProcessor::Status MergingSortedTransform::prepare()
if (need_data)
{
auto & input = *std::next(inputs.begin(), next_input_to_read);
if (!input.isFinished())
{
@ -180,7 +179,10 @@ IProcessor::Status MergingSortedTransform::prepare()
return Status::NeedData;
updateCursor(std::move(chunk), next_input_to_read);
pushToQueue(next_input_to_read);
if (has_collation)
queue_with_collation.push(cursors[next_input_to_read]);
else
queue_without_collation.push(cursors[next_input_to_read]);
need_data = false;
}
}
@ -197,8 +199,8 @@ void MergingSortedTransform::work()
merge(queue_without_collation);
}
template <typename TSortCursor>
void MergingSortedTransform::merge(std::priority_queue<TSortCursor> & queue)
template <typename TSortingHeap>
void MergingSortedTransform::merge(TSortingHeap & queue)
{
/// Returns MergeStatus which we should return if we are going to finish now.
auto can_read_another_row = [&, this]()
@ -220,29 +222,20 @@ void MergingSortedTransform::merge(std::priority_queue<TSortCursor> & queue)
};
/// Take rows in required order and put them into `merged_data`, while the rows are no more than `max_block_size`
while (!queue.empty())
while (queue.isValid())
{
/// Shouldn't happen at first iteration, but check just in case.
if (!can_read_another_row())
return;
TSortCursor current = queue.top();
queue.pop();
bool first_iteration = true;
while (true)
{
if (!first_iteration && !can_read_another_row())
{
queue.push(current);
return;
}
first_iteration = false;
auto current = queue.current();
/** And what if the block is totally less or equal than the rest for the current cursor?
* Or is there only one data source left in the queue? Then you can take the entire block on current cursor.
*/
if (current.impl->isFirst() && (queue.empty() || current.totallyLessOrEquals(queue.top())))
if (current.impl->isFirst()
&& (queue.size() == 1
|| (queue.size() >= 2 && current.totallyLessOrEquals(queue.nextChild()))))
{
//std::cerr << "current block is totally less or equals\n";
@ -250,7 +243,6 @@ void MergingSortedTransform::merge(std::priority_queue<TSortCursor> & queue)
if (merged_data.mergedRows() != 0)
{
//std::cerr << "merged rows is non-zero\n";
queue.push(current);
return;
}
@ -271,8 +263,17 @@ void MergingSortedTransform::merge(std::priority_queue<TSortCursor> & queue)
out_row_sources_buf->write(row_source.data);
}
if (current->isLast())
if (!current->isLast())
{
// std::cerr << "moving to next row\n";
queue.next();
}
else
{
/// We will get the next block from the corresponding source, if there is one.
queue.removeTop();
// std::cerr << "It was last row, fetching next block\n";
need_data = true;
next_input_to_read = current.impl->order;
@ -281,17 +282,6 @@ void MergingSortedTransform::merge(std::priority_queue<TSortCursor> & queue)
return;
}
//std::cerr << "moving to next row\n";
current->next();
if (!queue.empty() && current.greater(queue.top()))
{
//std::cerr << "next row is not least, pushing back to queue\n";
queue.push(current);
break;
}
}
}
is_finished = true;
}

29
dbms/src/Processors/Transforms/MergingSortedTransform.h
View File

@ -1,10 +1,10 @@
#pragma once
#include <Processors/IProcessor.h>
#include <Core/SortDescription.h>
#include <Core/SortCursor.h>
#include <Processors/SharedChunk.h>
#include <queue>
namespace DB
{
@ -113,11 +113,8 @@ protected:
SortCursorImpls cursors;
using Queue = std::priority_queue<SortCursor>;
Queue queue_without_collation;
using QueueWithCollation = std::priority_queue<SortCursorWithCollation>;
QueueWithCollation queue_with_collation;
SortingHeap<SortCursor> queue_without_collation;
SortingHeap<SortCursorWithCollation> queue_with_collation;
private:
@ -127,8 +124,8 @@ private:
bool need_data = false;
size_t next_input_to_read = 0;
template <typename TSortCursor>
void merge(std::priority_queue<TSortCursor> & queue);
template <typename TSortingHeap>
void merge(TSortingHeap & queue);
void insertFromChunk(size_t source_num);
@ -158,22 +155,6 @@ private:
shared_chunk_ptr->all_columns = cursors[source_num].all_columns;
shared_chunk_ptr->sort_columns = cursors[source_num].sort_columns;
}
void pushToQueue(size_t source_num)
{
if (has_collation)
queue_with_collation.push(SortCursorWithCollation(&cursors[source_num]));
else
queue_without_collation.push(SortCursor(&cursors[source_num]));
}
template <typename TSortCursor>
void initQueue(std::priority_queue<TSortCursor> & queue)
{
for (auto & cursor : cursors)
if (!cursor.empty())
queue.push(TSortCursor(&cursor));
}
};
}