C++ StoragePtr::getTableName方法代码示例

StorageMerge::StorageListWithLocks StorageMerge::getSelectedTables(const ASTPtr & query, bool has_virtual_column, bool get_lock) const
{
    StorageListWithLocks selected_tables;
    DatabasePtr database = global_context.getDatabase(source_database);
    DatabaseIteratorPtr iterator = database->getIterator(global_context);

    auto virtual_column = ColumnString::create();

    while (iterator->isValid())
    {
        if (table_name_regexp.match(iterator->name()))
        {
            StoragePtr storage = iterator->table();

            if (query && typeid_cast<ASTSelectQuery *>(query.get())->prewhere_expression && !storage->supportsPrewhere())
                throw Exception("Storage " + storage->getName() + " doesn't support PREWHERE.", ErrorCodes::ILLEGAL_PREWHERE);

            if (storage.get() != this)
            {
                virtual_column->insert(storage->getTableName());
                selected_tables.emplace_back(storage, get_lock ? storage->lockStructure(false) : TableStructureReadLockPtr{});
            }
        }

        iterator->next();
    }

    if (has_virtual_column)
    {
        Block virtual_columns_block = Block{ColumnWithTypeAndName(std::move(virtual_column), std::make_shared<DataTypeString>(), "_table")};
        VirtualColumnUtils::filterBlockWithQuery(query, virtual_columns_block, global_context);
        auto values = VirtualColumnUtils::extractSingleValueFromBlock<String>(virtual_columns_block, "_table");

        /// Remove unused tables from the list
        selected_tables.remove_if([&] (const auto & elem) { return values.find(elem.first->getTableName()) == values.end(); });
    }

    return selected_tables;
}

BlockInputStreams StorageMerge::createSourceStreams(const SelectQueryInfo & query_info, const QueryProcessingStage::Enum & processed_stage,
                                                    const size_t max_block_size, const Block & header, const StoragePtr & storage,
                                                    const TableStructureReadLockPtr & struct_lock, Names & real_column_names,
                                                    Context & modified_context, size_t streams_num, bool has_table_virtual_column,
                                                    bool concat_streams)
{
    SelectQueryInfo modified_query_info = query_info;
    modified_query_info.query = query_info.query->clone();

    VirtualColumnUtils::rewriteEntityInAst(modified_query_info.query, "_table", storage ? storage->getTableName() : "");

    if (!storage)
        return BlockInputStreams{
            InterpreterSelectQuery(modified_query_info.query, modified_context, std::make_shared<OneBlockInputStream>(header),
                                   processed_stage, true).execute().in};

    BlockInputStreams source_streams;

    if (processed_stage <= storage->getQueryProcessingStage(modified_context))
    {
        /// If there are only virtual columns in query, you must request at least one other column.
        if (real_column_names.size() ==0)
            real_column_names.push_back(ExpressionActions::getSmallestColumn(storage->getColumns().getAllPhysical()));

        source_streams = storage->read(real_column_names, modified_query_info, modified_context, processed_stage, max_block_size,
                                       UInt32(streams_num));
    }
    else if (processed_stage > storage->getQueryProcessingStage(modified_context))
    {
        typeid_cast<ASTSelectQuery *>(modified_query_info.query.get())->replaceDatabaseAndTable(source_database, storage->getTableName());

        /// Maximum permissible parallelism is streams_num
        modified_context.getSettingsRef().max_threads = UInt64(streams_num);
        modified_context.getSettingsRef().max_streams_to_max_threads_ratio = 1;

        InterpreterSelectQuery interpreter{modified_query_info.query, modified_context, Names{}, processed_stage};
        BlockInputStreamPtr interpreter_stream = interpreter.execute().in;

        /** Materialization is needed, since from distributed storage the constants come materialized.
          * If you do not do this, different types (Const and non-Const) columns will be produced in different threads,
          * And this is not allowed, since all code is based on the assumption that in the block stream all types are the same.
          */
        source_streams.emplace_back(std::make_shared<MaterializingBlockInputStream>(interpreter_stream));
    }

    if (!source_streams.empty())
    {
        if (concat_streams)
        {
            BlockInputStreamPtr stream =
                source_streams.size() > 1 ? std::make_shared<ConcatBlockInputStream>(source_streams) : source_streams[0];

            source_streams.resize(1);
            source_streams[0] = stream;
        }

        for (BlockInputStreamPtr & source_stream : source_streams)
        {
            if (has_table_virtual_column)
                source_stream = std::make_shared<AddingConstColumnBlockInputStream<String>>(
                    source_stream, std::make_shared<DataTypeString>(), storage->getTableName(), "_table");

            /// Subordinary tables could have different but convertible types, like numeric types of different width.
            /// We must return streams with structure equals to structure of Merge table.
            convertingSourceStream(header, modified_context, modified_query_info.query, source_stream, processed_stage);

            source_stream->addTableLock(struct_lock);
        }
    }

    return source_streams;
}