ClickHouse/src/Storages/StorageNull.cpp

#include <Storages/StorageNull.h>
#include <Storages/StorageFactory.h>
#include <Storages/AlterCommands.h>

#include <Interpreters/InterpreterAlterQuery.h>
#include <Interpreters/Context.h>
#include <Databases/IDatabase.h>

#include <IO/WriteHelpers.h>


namespace DB
{

namespace ErrorCodes
{
    extern const int NOT_IMPLEMENTED;
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}


void registerStorageNull(StorageFactory & factory)
{
    factory.registerStorage("Null", [](const StorageFactory::Arguments & args)
    {
        if (!args.engine_args.empty())
            throw Exception(
                "Engine " + args.engine_name + " doesn't support any arguments (" + toString(args.engine_args.size()) + " given)",
                ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

        return StorageNull::create(args.table_id, args.columns, args.constraints);
    });
}

void StorageNull::checkAlterIsPossible(const AlterCommands & commands, const Settings & /* settings */)
{
    for (const auto & command : commands)
    {
        if (command.type != AlterCommand::Type::ADD_COLUMN && command.type != AlterCommand::Type::MODIFY_COLUMN
            && command.type != AlterCommand::Type::DROP_COLUMN && command.type != AlterCommand::Type::COMMENT_COLUMN)
            throw Exception(
                "Alter of type '" + alterTypeToString(command.type) + "' is not supported by storage " + getName(),
                ErrorCodes::NOT_IMPLEMENTED);
    }
}


void StorageNull::alter(
    const AlterCommands & params, const Context & context, TableStructureWriteLockHolder & table_lock_holder)
{
    lockStructureExclusively(table_lock_holder, context.getCurrentQueryId(), context.getSettingsRef().lock_acquire_timeout);
    auto table_id = getStorageID();

    StorageInMemoryMetadata metadata = getInMemoryMetadata();
    params.apply(metadata, context);
    DatabaseCatalog::instance().getDatabase(table_id.database_name)->alterTable(context, table_id, metadata);
    setColumns(std::move(metadata.columns));
}

}