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

#pragma once

#include <DB/Core/Block.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/Dictionaries/ExternalResultDescription.h>

#include <Poco/Data/Session.h>
#include <Poco/Data/Statement.h>
#include <Poco/Data/RecordSet.h>

#include <string>


namespace DB
{

/// Allows processing results of a query to ODBC source as a sequence of Blocks, simplifies chaining
class ODBCBlockInputStream final : public IProfilingBlockInputStream
{
public:
	ODBCBlockInputStream(
		Poco::Data::Session && session, const std::string & query_str, const Block & sample_block,
		const std::size_t max_block_size);

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

	String getID() const override;

private:
	Block readImpl() override;

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

	Poco::Data::Session session;
	Poco::Data::Statement statement;
	Poco::Data::RecordSet result;
	Poco::Data::RecordSet::Iterator iterator;

	const std::size_t max_block_size;
	ExternalResultDescription description;
};

}