ClickHouse/src/Storages/StorageView.h
2021-04-23 12:18:23 +00:00

56 lines
1.8 KiB
C++

#pragma once
#include <Parsers/ASTSelectQuery.h>
#include <Parsers/IAST_fwd.h>
#include <Storages/IStorage.h>
#include <ext/shared_ptr_helper.h>
namespace DB
{
class StorageView final : public ext::shared_ptr_helper<StorageView>, public IStorage
{
friend struct ext::shared_ptr_helper<StorageView>;
public:
std::string getName() const override { return "View"; }
bool isView() const override { return true; }
/// It is passed inside the query and solved at its level.
bool supportsSampling() const override { return true; }
bool supportsFinal() const override { return true; }
Pipe read(
const Names & column_names,
const StorageMetadataPtr & /*metadata_snapshot*/,
SelectQueryInfo & query_info,
ContextPtr context,
QueryProcessingStage::Enum processed_stage,
size_t max_block_size,
unsigned num_streams) override;
void read(
QueryPlan & query_plan,
const Names & column_names,
const StorageMetadataPtr & metadata_snapshot,
SelectQueryInfo & query_info,
ContextPtr context,
QueryProcessingStage::Enum processed_stage,
size_t max_block_size,
unsigned num_streams) override;
void replaceWithSubquery(ASTSelectQuery & select_query, ASTPtr & view_name, const StorageMetadataPtr & metadata_snapshot) const
{
replaceWithSubquery(select_query, metadata_snapshot->getSelectQuery().inner_query->clone(), view_name);
}
static void replaceWithSubquery(ASTSelectQuery & outer_query, ASTPtr view_query, ASTPtr & view_name);
static ASTPtr restoreViewName(ASTSelectQuery & select_query, const ASTPtr & view_name);
protected:
StorageView(const StorageID & table_id_, const ASTCreateQuery & query, const ColumnsDescription & columns_, const String & comment);
};
}