ClickHouse/dbms/include/DB/Storages/MergeTree/MergeTreeDataWriter.h

#pragma once

#include <DB/IO/WriteBufferFromFile.h>
#include <DB/IO/CompressedWriteBuffer.h>

#include <DB/Columns/ColumnsNumber.h>

#include <DB/Interpreters/sortBlock.h>

#include <DB/Storages/MergeTree/MergeTreeData.h>


namespace DB
{

struct BlockWithDateInterval
{
	Block block;
	UInt16 min_date = std::numeric_limits<UInt16>::max(); /// For further updating, see updateDates method.
	UInt16 max_date = std::numeric_limits<UInt16>::min();

	BlockWithDateInterval() = default;
	BlockWithDateInterval(const Block & block_, UInt16 min_date_, UInt16 max_date_)
		: block(block_), min_date(min_date_), max_date(max_date_) {}

	void updateDates(UInt16 date)
	{
		if (date < min_date)
			min_date = date;

		if (date > max_date)
			max_date = date;
	}
};

using BlocksWithDateIntervals = std::list<BlockWithDateInterval>;

/** Записывает новые куски с данными в merge-дерево.
  */
class MergeTreeDataWriter
{
public:
	MergeTreeDataWriter(MergeTreeData & data_) : data(data_), log(&Logger::get(data.getLogName() + " (Writer)")) {}

	/** Split the block to blocks, each of them must be written as separate part.
	  *  (split rows by months)
	  * Works deterministically: if same block was passed, function will return same result in same order.
	  */
	BlocksWithDateIntervals splitBlockIntoParts(const Block & block);

	/** All rows must correspond to same month.
	  * 'temp_index' - value for 'left' and 'right' for new part. Could be changed later at rename.
	  * Returns part with name starting with 'tmp_', yet not added to MergeTreeData.
	  */
	MergeTreeData::MutableDataPartPtr writeTempPart(BlockWithDateInterval & block, Int64 temp_index);

private:
	MergeTreeData & data;

	Logger * log;
};

}