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/Interpreters/Context.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_, Context & context_) : data(data_), context(context_), 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;
    Context & context;

    Logger * log;
};

}