ClickHouse/dbms/include/DB/Interpreters/executeQuery.h

#pragma once

#include <DB/Core/QueryProcessingStage.h>
#include <DB/DataStreams/BlockIO.h>


namespace DB
{


/// Parse and execute a query.
void executeQuery(
	ReadBuffer & istr,					/// Where to read query from (and data for INSERT, if present).
	WriteBuffer & ostr,					/// Where to write query output to.
	bool allow_into_outfile,			/// If true and the query contains INTO OUTFILE section, redirect output to that file.
	Context & context,					/// DB, tables, data types, storage engines, functions, aggregate functions...
	std::function<void(const String &)> set_content_type /// If non-empty callback is passed, it will be called with the Content-Type of the result.
	);


/// More low-level function for server-to-server interaction.
/// Prepares a query for execution but doesn't execute it.
/// Returns a pair of block streams which, when used, will result in query execution.
/// This means that the caller can to the extent control the query execution pipeline.
///
/// To execute:
/// * if present, write INSERT data into BlockIO::out
/// * then read the results from BlockIO::in.
///
/// If the query doesn't involve data insertion or returning of results, out and in respectively
/// will be equal to nullptr.
///
/// Correctly formatting the results (according to INTO OUTFILE and FORMAT sections)
/// must be done separately.
BlockIO executeQuery(
	const String & query,	/// Query text without INSERT data. The latter must be written to BlockIO::out.
	Context & context,		/// DB, tables, data types, storage engines, functions, aggregate functions...
	bool internal = false,	/// If true, this query is caused by another query and thus needn't be registered in the ProcessList.
	QueryProcessingStage::Enum stage = QueryProcessingStage::Complete	/// To which stage the query must be executed.
	);

}