ClickHouse/dbms/src/Storages/StorageView.cpp

#include <DB/Interpreters/InterpreterSelectQuery.h>
#include <DB/Parsers/ASTIdentifier.h>
#include <DB/Parsers/ASTCreateQuery.h>
#include <DB/Parsers/ASTSelectQuery.h>

#include <DB/Storages/StorageView.h>


namespace DB
{


StoragePtr StorageView::create(
	const String & table_name_,
	const String & database_name_,
	Context & context_,
	ASTPtr & query_,
	NamesAndTypesListPtr columns_,
	const NamesAndTypesList & materialized_columns_,
	const NamesAndTypesList & alias_columns_,
	const ColumnDefaults & column_defaults_)
{
	return (new StorageView{
		table_name_, database_name_, context_, query_,
		columns_, materialized_columns_, alias_columns_, column_defaults_
	})->thisPtr();
}


StorageView::StorageView(
	const String & table_name_,
	const String & database_name_,
	Context & context_,
	ASTPtr & query_,
	NamesAndTypesListPtr columns_,
	const NamesAndTypesList & materialized_columns_,
	const NamesAndTypesList & alias_columns_,
	const ColumnDefaults & column_defaults_)
	: IStorage{materialized_columns_, alias_columns_, column_defaults_}, table_name(table_name_),
	database_name(database_name_), context(context_), columns(columns_)
{
	ASTCreateQuery & create = typeid_cast<ASTCreateQuery &>(*query_);
	ASTSelectQuery & select = typeid_cast<ASTSelectQuery &>(*create.select);

	/// Если во внутреннем запросе не указана база данных, получить ее из контекста и записать в запрос.
	if (!select.database)
	{
		select.database = new ASTIdentifier(StringRange(), database_name_, ASTIdentifier::Database);
		select.children.push_back(select.database);
	}

	inner_query = select;

	if (inner_query.database)
		select_database_name = typeid_cast<const ASTIdentifier &>(*inner_query.database).name;
	else
		throw Exception("Logical error while creating StorageView."
			" Could not retrieve database name from select query.",
			DB::ErrorCodes::LOGICAL_ERROR);

	if (inner_query.table)
		select_table_name = typeid_cast<const ASTIdentifier &>(*inner_query.table).name;
	else
		throw Exception("Logical error while creating StorageView."
			" Could not retrieve table name from select query.",
			DB::ErrorCodes::LOGICAL_ERROR);

	context.getGlobalContext().addDependency(
		DatabaseAndTableName(select_database_name, select_table_name),
		DatabaseAndTableName(database_name, table_name));
}


BlockInputStreams StorageView::read(
	const Names & column_names,
	ASTPtr query,
	const Settings & settings,
	QueryProcessingStage::Enum & processed_stage,
	size_t max_block_size,
	unsigned threads)
{
	ASTPtr inner_query_clone = getInnerQuery();
	ASTSelectQuery & inner_select = static_cast<ASTSelectQuery &>(*inner_query_clone);
	const ASTSelectQuery & outer_select = typeid_cast<const ASTSelectQuery &>(*query);

	/// Пробрасываем внутрь SAMPLE и FINAL, если они есть во внешнем запросе и их нет во внутреннем.

	if (outer_select.sample_size && !inner_select.sample_size)
		inner_select.sample_size = outer_select.sample_size;

	if (outer_select.final && !inner_select.final)
		inner_select.final = outer_select.final;

	return BlockInputStreams(1,
		InterpreterSelectQuery(inner_query_clone, context, column_names).execute());
}


void StorageView::drop()
{
	context.getGlobalContext().removeDependency(
		DatabaseAndTableName(select_database_name, select_table_name),
		DatabaseAndTableName(database_name, table_name));
}


}