StorageSet.h

// Copyright 2023 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#pragma once

#include <Storages/IStorage.h>

#include <ext/shared_ptr_helper.h>


namespace DB
{
class Set;
using SetPtr = std::shared_ptr<Set>;


/** Common part of StorageSet and StorageJoin.
  */
class StorageSetOrJoinBase : public IStorage
{
    friend class SetOrJoinBlockOutputStream;

public:
    String getTableName() const override { return table_name; }

    void rename(const String & new_path_to_db, const String & new_database_name, const String & new_table_name)
        override;

    BlockOutputStreamPtr write(const ASTPtr & query, const Settings & settings) override;

    String getDataPath() const override { return path; }

protected:
    StorageSetOrJoinBase(const String & path_, const String & table_name_, const ColumnsDescription & columns_);

    String path;
    String table_name;

    UInt64 increment = 0; /// For the backup file names.

    /// Restore from backup.
    void restore();

private:
    void restoreFromFile(const String & file_path);

    /// Insert the block into the state.
    virtual void insertBlock(const Block & block) = 0;
    virtual size_t getSize() const = 0;
};


/** Lets you save the set for later use on the right side of the IN statement.
  * When inserted into a table, the data will be inserted into the set,
  *  and also written to a file-backup, for recovery after a restart.
  * Reading from the table is not possible directly - it is possible to specify only the right part of the IN statement.
  */
class StorageSet
    : public ext::SharedPtrHelper<StorageSet>
    , public StorageSetOrJoinBase
{
    friend struct ext::SharedPtrHelper<StorageSet>;

public:
    String getName() const override { return "Set"; }

    /// Access the insides.
    SetPtr & getSet() { return set; }

private:
    SetPtr set;

    void insertBlock(const Block & block) override;
    size_t getSize() const override;

protected:
    StorageSet(const String & path_, const String & name_, const ColumnsDescription & columns_);
};

} // namespace DB