SQL 服务器：具有软删除功能的 Graph-DB 未按预期工作

Question

我尝试使用 SQL 服务器中的图形功能。现在我遇到了软删除问题。

我有下图

[1] -> [2] -> [9 (deleted)] -> [4]

当我运行下面的脚本

CREATE TABLE MyNode 
(
    [Id] [bigint] NOT NULL,
    [IsDeleted] [bit] NOT NULL,
) AS NODE;

CREATE TABLE MyEdge 
(
    State [int] NOT NULL
) AS EDGE;

INSERT INTO MyNode (Id, IsDeleted)
VALUES (1, 0), (2, 0), (4, 0), (9, 1);

INSERT INTO MyEdge
VALUES
( (SELECT $node_id FROM MyNode WHERE Id = 1), (SELECT $node_id FROM MyNode WHERE Id = 2), 1),
( (SELECT $node_id FROM MyNode WHERE Id = 2), (SELECT $node_id FROM MyNode WHERE Id = 9), 1),
( (SELECT $node_id FROM MyNode WHERE Id = 9), (SELECT $node_id FROM MyNode WHERE Id = 4), 1)
;

SELECT
    src.Id ID_SOURCE
,   LAST_VALUE(trgt.Id) WITHIN GROUP (GRAPH PATH) AS ID_TARGET
,   STRING_AGG(trgt.Id, '->') WITHIN GROUP (GRAPH PATH) AS ID_CHAIN
--, STRING_AGG(compare.State, '->') WITHIN GROUP (GRAPH PATH) AS STATE_CHAIN
--, STRING_AGG(trgt.IsDeleted, '->') WITHIN GROUP (GRAPH PATH) AS DELETED_CHAIN
FROM
    MyNode AS src
,   (   SELECT
            *
        FROM
            MyEdge
        WHERE
            State = 1
    ) FOR PATH AS compare
,   (   SELECT
            *
        FROM
            MyNode
        WHERE
            IsDeleted = 0
    ) FOR PATH AS trgt
WHERE
    MATCH ( SHORTEST_PATH( src(-(compare)->trgt)+ ) )
    AND src.Id = 1;

SELECT
    src.Id AS SOURCE_ID
,   ed.State AS EDGE_STATE
,   trgt.Id AS TARGET_ID
FROM
    MyNode AS src
,   MyEdge AS ed
,   MyNode AS trgt
WHERE
    MATCH( src-(ed)->trgt )
    AND src.Id = 2;


DROP TABLE MyNode;
DROP TABLE MyEdge;

（提示：这仅适用于 SQL-Server 2019）

我得到以下结果

ID_SOURCE	ID_TARGET	ID_CHAIN
1	2	2
1	4	2->4

没有边 2->4 但 2->9->4。但是节点 9 被删除，因此它用于图形遍历但在输出中被抑制。

这是 SQL 服务器中的错误还是我做错了什么？

或者还有其他方法可以使用 Graph-DB 软删除吗？

Answer 1

您可以过滤掉边缘from/to 软删除节点

....
(   
SELECT e.*
FROM MyEdge as e
WHERE
    e.State = 1
    and exists(select * from MyNode as x where x.IsDeleted = 0 and x.$node_id = e.$to_id)
    --and exists(select * from MyNode as x where x.IsDeleted = 0 and x.$node_id = e.$from_id)
) FOR PATH AS compare
....

不知何故，以下查询 returns 出错（执行几秒后）：

SELECT
    src.Id ID_SOURCE
,   LAST_VALUE(trgt.Id) WITHIN GROUP (GRAPH PATH) AS ID_TARGET
,   STRING_AGG(trgt.Id, '->') WITHIN GROUP (GRAPH PATH) AS ID_CHAIN
--, STRING_AGG(compare.State, '->') WITHIN GROUP (GRAPH PATH) AS STATE_CHAIN
--, STRING_AGG(trgt.IsDeleted, '->') WITHIN GROUP (GRAPH PATH) AS DELETED_CHAIN
FROM
    MyNode AS src
,   
(   
SELECT e.*
FROM MyEdge as e
WHERE
    e.State = 1
    and exists(select * from MyNode as x where x.IsDeleted = 0 and x.$node_id = e.$to_id)
    --and exists(select * from MyNode as x where x.IsDeleted = 0 and x.$node_id = e.$from_id)
) FOR PATH AS compare

,   (   SELECT
            *
        FROM
            MyNode
        WHERE
            IsDeleted = 0
    ) FOR PATH AS trgt
WHERE
    MATCH ( SHORTEST_PATH( src(-(compare)->trgt)+ ) )

...并且通过将 condition/reference 附加到 src table 来消除错误，这始终为真：

AND src.Id = src.Id --or src.IsDeleted = src.IsDeleted

肯定有问题 [Microsoft SQL Server 2019 (RTM-CU8-GDR) (KB4583459)]..

Answer 2

将 isDeleted 标志合并到边 table 中，并在相应的 (to/from) 节点被标记为软删除时更新该标志，并在边上使用 isDeleted table 子查询，是首选方式。我们不建议直接比较 $node_id 和 $from_id，除非通过 MATCH 函数隐式比较。

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