ClickHouse/dbms/include/DB/Dictionaries/MySQLBlockInputStream.h

#pragma once

#include <DB/Core/Block.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/Dictionaries/ExternalResultDescription.h>
#include <mysqlxx/Query.h>
#include <mysqlxx/PoolWithFailover.h>
#include <string>


namespace DB
{

/// Allows processing results of a MySQL query as a sequence of Blocks, simplifies chaining
class MySQLBlockInputStream final : public IProfilingBlockInputStream
{
public:
	MySQLBlockInputStream(
		const mysqlxx::PoolWithFailover::Entry & entry, const std::string & query_str, const Block & sample_block,
		const size_t max_block_size);

	String getName() const override { return "MySQL"; }

	String getID() const override;

private:
	Block readImpl() override;

	static void insertDefaultValue(IColumn * const column, const IColumn & sample_column)
	{
		column->insertFrom(sample_column, 0);
	}

	mysqlxx::PoolWithFailover::Entry entry;
	mysqlxx::Query query;
	mysqlxx::UseQueryResult result;
	const size_t max_block_size;
	ExternalResultDescription description;
};

}