Question

我正在使用PHP与MongoDB交互，最近我在5个集合上使用$lookup，我的查询开始花费大约20-25秒来获得结果。我的所有馆藏都有不超过30-40个条目的测试数据。我也使用了分析，但我收到消息：＆＃34;查询不记录（太大）＆＃34;

我正在从我的PHP文件中共享代码。我也尝试在字段上创建索引，它们在集合之间创建连接但得到相同的结果。请告诉我创建集合结构和从MongoDB检索数据的最佳方法。

提前致谢。

    $collection = new MongoCollection($db, 'col_main');
    $condition = array();
    $condition[] = array(
            '$lookup' => array(
                "from" => "col_a",
                "localField" => "a",
                "foreignField" => "_id",
                "as" => "col_a"
            )
        );
    $condition[] = array(
            '$lookup' => array(
                "from" => "col_b",
                "localField" => "b",
                "foreignField" => "_id",
                "as" => "col_b"
            )
        );

    $condition[] = array(
            '$lookup' => array(
                "from" => "col_c",
                "localField" => "c",
                "foreignField" => "_id",
                "as" => "col_c"
            )
        );

    $condition[] = array(
            '$lookup' => array(
                "from" => "col_e",
                "localField" => "e",
                "foreignField" => "_id",
                "as" => "col_e"
            )
        );

    $condition[] = array(
            '$lookup' => array(
                "from" => "col_f",
                "localField" => "f",
                "foreignField" => "_id",
                "as" => "col_f"
            )
        );      

    $condition[]  = array(
            '$project' => $projection
        );

    $condition[] = array ( 
                    '$unwind' => '$col_a'

                );

    $condition[] = array (
                    '$unwind' => '$col_a.translation'

                );      

    $condition[] = array ( 
                    '$unwind' => '$col_b'

                );

    $condition[] = array (
                    '$unwind' => '$col_b.translation'

                );

    $condition[] = array ( 
                    '$unwind' => '$col_c'

                );

    $condition[] = array (
                    '$unwind' => '$col_c.translation'

                );

    $condition[] = array ( 
                    '$unwind' => '$col_e'

                );

    $condition[] = array (
                    '$unwind' => '$col_e.staff_name'

                );

    $condition[] = array (
                    '$unwind' => '$col_e.staff_surname'

                );          

    $condition[] = array ( 
                    '$unwind' => '$col_f'

                );

    $condition[] = array (
                    '$unwind' => '$col_f.translation'

                );      


    //Some More conditions

        $condition[] = array(
                    '$match' => array( 'col_b.translation.language' => $val )
                );
            $condition[] = array(
                    '$match' => array( 'col_a.translation.language' => $val )
                );
            $condition[] = array(
                    '$match' => array( 'col_c.translation.language' => $val )
                );  

            $condition[] = array(
                    '$match' => array( 'col_f.translation.language' => $val )
                );              


    return  $collection->aggregate($condition);

Answer 1

当您使用许多展开操作将对象相乘时，这可能会产生大量数据，每个$unwind多个文档都会设置，因此可能会有大量内存消耗甚至交换。

如果我们每个有3个数组3个元素，那么我们将在a，b，c上执行展开我们会得到：

第一步后的3个文件，
第二步后的9个文件
最后一步后的27个文件..

使用$ lookup

1 个答案: