ClickHouse/dbms/include/DB/Storages/MergeTree/MergeTreeDataWriter.h
2017-04-01 11:35:09 +03:00

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#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;
};
}