Teradataストアドプロシージャで再帰クエリを処理できません

Question

私はこのSPをT-SQLからTeradata SQLにhttp://hansolav.net/sql/graphs.html#dijkstraで変換しようとしています。私は再帰的なクエリとは別にそのほとんどを行ってきました。私は、Teradata SPが再帰的クエリを処理できないことを理解しています。誰もがこのSPを動作させるために再帰的なクエリビットを書き直す方法を知っていますか？あなたは再帰を使用することができます古いTeradataのバージョンを実行するが、任意のDECLAREはブロック内で最初に行われなければならない限り、我々は現在、ここでTD 16

を使用している

は私のコード

CREATE VOLATILE TABLE VT_Nodes 
(
    Id INT, -- The Node Id 
    Estimate DECIMAL(10,3) , -- What is the distance to this node, so far? 
    Predecessor INT, -- The node we came from to get to this node with this distance. 
    Done SMALLINT  -- Are we done with this node yet (is the estimate the final distance)? 
)PRIMARY INDEX(id) 
ON COMMIT PRESERVE ROWS; 




CREATE PROCEDURE db.usp_Dijkstra 
(
StartNode INT 
, EndNode INT /*= NULL*/ 
) 
SQL SECURITY INVOKER 
BEGIN 
/* -- Automatically rollback the transaction if something goes wrong.  
    SET XACT_ABORT ON  
    BEGIN TRAN 
    */ 
-- Increase performance and do not intefere with the results. 
    --SET NOCOUNT ON; 

    DECLARE FromNode INT; 
    DECLARE CurrentEstimate INT; 

    -- Fill the temporary table with initial data 
    INSERT INTO VT_Nodes (Id, Estimate, Predecessor, Done) 
    SELECT Id, 9999999.999, NULL, 0 FROM db.T_NODE; 

    -- Set the estimate for the node we start in to be 0. 
    UPDATE VT_Nodes SET Estimate = 0 WHERE Id =StartNode; 
/* IF @@rowcount <> 1 
    BEGIN 
     DROP TABLE VT_Nodes 
     RAISERROR ('Could not set start node', 11, 1) 
     ROLLBACK TRAN   
     RETURN 1 
    END*/ 



    -- Run the algorithm until we decide that we are finished 
label1: 
    WHILE (1 = 1) DO 
BEGIN 
     -- Reset the variable, so we can detect getting no records in the next step. 
     SET FromNode = NULL; 

     -- Select the Id and current estimate for a node not done, with the lowest estimate. 
    SET FromNode = (SELECT TOP 1 Id FROM VT_Nodes WHERE Done = 0 AND Estimate < 9999999.999 ORDER BY Estimate); 
    SET CurrentEstimate = (SELECT TOP 1 Estimate FROM VT_Nodes WHERE Done = 0 AND Estimate < 9999999.999 ORDER BY Estimate); 

     -- Stop if we have no more unvisited, reachable nodes. 
     IF FromNode IS NULL OR FromNode = EndNode THEN 
    LEAVE label1; 
    END IF; 

     -- We are now done with this node. 
     UPDATE VT_Nodes 
    SET Done = 1 
    WHERE Id = FromNode; 

     -- Update the estimates to all neighbour node of this one (all the nodes 
     -- there are edges to from this node). Only update the estimate if the new 
     -- proposal (to go via the current node) is better (lower). 

    UPDATE VT_Nodes 
    FROM db.T_Edge AS e 
    SET Estimate = CurrentEstimate + e.Weight 
    , Predecessor = FromNode 
    WHERE VT_Nodes.Id = e.ToNode 
    AND e.FromNode = FromNode 
    AND (CurrentEstimate + e.Weight) < VT_Nodes.Estimate 
    AND Done = 0 
     ; 
END ; 
END WHILE label1; 

DECLARE CUR1 CURSOR WITH RETURN ONLY TO CLIENT FOR 
-- Select the results. We use a recursive common table expression to 
-- get the full path from the start node to the current node. 
WITH RECURSIVE BacktraceCTE(Id, nm, Distance, PATH, NamePath) 
AS 
(
    -- Anchor/base member of the recursion, this selects the start node. 
    SELECT n.Id 
    , nd.nm 
    , n.Estimate 
    , CAST(n.Id AS VARCHAR(8000)) AS PATH 
    ,CAST(nd.nm AS VARCHAR(8000)) AS NamePath 
    FROM VT_Nodes AS n 
    JOIN db.T_NODE AS nd 
    ON n.Id = nd.Id 
    WHERE n.Id = StartNode 

    UNION ALL 

    -- Recursive member, select all the nodes which have the previous 
    -- one as their predecessor. Concat the paths together. 
    SELECT n.Id 
    , nd.nm 
    , n.Estimate 
    ,CAST((cte.PATH || ',' ||TRIM(n.Id)) AS VARCHAR(8000)) 
    ,CAST((cte.NamePath || ',' || nd.nm) AS VARCHAR(8000)) 
    FROM VT_Nodes n 
    JOIN BacktraceCTE AS cte 
    ON n.Predecessor = cte.Id 
    JOIN db.T_NODE AS nd 
    ON n.Id = nd.Id 
) 
SELECT Id 
, nm 
, Distance 
, PATH 
, NamePath 
FROM BacktraceCTE 
WHERE (Id = EndNode OR EndNode IS NULL) -- This kind of where clause can potentially produce 
ORDER BY Id  -- a bad execution plan, but I use it for simplicity here. 
; 

OPEN CUR1; 

    DROP TABLE VT_Nodes; 
/* COMMIT TRAN 
    RETURN 0*/ 
END ; 







Tables 

CREATE TABLE DB.T_NODE 
( 
    Id INT 
    ,Nm VARCHAR(50) 
)PRIMARY INDEX(id) 
; 


CREATE TABLE DB.T_Edge 
(
    FromNode INT , 
    ToNode INT, 
    Weight DECIMAL (10, 3) 
) PRIMARY INDEX(FromNode ,ToNode) 
; 







DATA 
INSERT DB.T_NODE (Id, Nm) VALUES (1, 'Seattle'); 
INSERT DB.T_NODE (Id, Nm) VALUES (2, 'San Francisco'); 
INSERT DB.T_NODE (Id, Nm) VALUES (3, 'Las Vegas'); 
INSERT DB.T_NODE (Id, Nm) VALUES (4, 'Los Angeles'); 
INSERT DB.T_NODE (Id, Nm) VALUES (5, 'Denver'); 
INSERT DB.T_NODE (Id, Nm) VALUES (6, 'Minneapolis'); 
INSERT DB.T_NODE (Id, Nm) VALUES (7, 'Dallas'); 
INSERT DB.T_NODE (Id, Nm) VALUES (8, 'Chicago'); 
INSERT DB.T_NODE (Id, Nm) VALUES (9, 'Washington DC'); 
INSERT DB.T_NODE (Id, Nm) VALUES (10, 'Boston'); 
INSERT DB.T_NODE (Id, Nm) VALUES (11, 'New York'); 
INSERT DB.T_NODE (Id, Nm) VALUES (12, 'Miami'); 





INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (1, 2, 1306.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (1, 5, 2161.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (1, 6, 2661.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (2, 1, 1306.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (2, 3, 919.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (2, 4, 629.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (3, 2, 919.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (3, 4, 435.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (3, 5, 1225.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (3, 7, 1983.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (4, 2, 629.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (4, 3, 435.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (5, 1, 2161.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (5, 3, 1225.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (5, 6, 1483.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (5, 7, 1258.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (6, 1, 2661.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (6, 5, 1483.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (6, 7, 1532.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (6, 8, 661.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (7, 3, 1983.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (7, 5, 1258.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (7, 6, 1532.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (7, 9, 2113.000); 
INSERT DB.T_Edge (FromNode, ToNode, Weight) VALUES (7, 12, 2161.000); 

Answer 1

です。わずかな変更が必要です：

REPLACE PROCEDURE usp_Dijkstra 
(
StartNode INT 
, EndNode INT /*= NULL*/ 
) 
SQL SECURITY INVOKER 
BEGIN 
/* -- Automatically rollback the transaction if something goes wrong.  
    SET XACT_ABORT ON  
    BEGIN TRAN 
    */ 
-- Increase performance and do not intefere with the results. 
    --SET NOCOUNT ON; 

    DECLARE FromNode INT; 
    DECLARE CurrentEstimate INT; 

    -- Fill the temporary table with initial data 
    INSERT INTO VT_Nodes (Id, Estimate, Predecessor, Done) 
    SELECT Id, 9999999.999, NULL, 0 FROM T_NODE; 

    -- Set the estimate for the node we start in to be 0. 
    UPDATE VT_Nodes SET Estimate = 0 WHERE Id =StartNode; 
/* IF @@rowcount <> 1 
    BEGIN 
     DROP TABLE VT_Nodes 
     RAISERROR ('Could not set start node', 11, 1) 
     ROLLBACK TRAN   
     RETURN 1 
    END*/ 



    -- Run the algorithm until we decide that we are finished 
label1: 
    WHILE (1 = 1) DO 
BEGIN 
     -- Reset the variable, so we can detect getting no records in the next step. 
     SET FromNode = NULL; 

     -- Select the Id and current estimate for a node not done, with the lowest estimate. 
-- replacing two SET with a single SELECT 
SELECT TOP 1 Id, Estimate INTO FromNode, CurrentEstimate 
FROM VT_Nodes WHERE Done = 0 AND Estimate < 9999999.999 ORDER BY Estimate; 

     -- Stop if we have no more unvisited, reachable nodes. 
     IF FromNode IS NULL OR FromNode = EndNode THEN 
    LEAVE label1; 
    END IF; 

     -- We are now done with this node. 
     UPDATE VT_Nodes 
    SET Done = 1 
    WHERE Id = FromNode; 

     -- Update the estimates to all neighbour node of this one (all the nodes 
     -- there are edges to from this node). Only update the estimate if the new 
     -- proposal (to go via the current node) is better (lower). 

    UPDATE VT_Nodes 
    FROM T_Edge AS e 
    SET Estimate = :CurrentEstimate + e.Weight 
    , Predecessor = :FromNode 
    WHERE VT_Nodes.Id = e.ToNode 
    AND e.FromNode = :FromNode 
    AND (:CurrentEstimate + e.Weight) < VT_Nodes.Estimate 
    AND Done = 0 
     ; 
END ; 
END WHILE label1; 

BEGIN -- wrap the cursor within a new BEGIN/END block 
    DECLARE CUR1 CURSOR WITH RETURN ONLY TO CLIENT FOR 
    -- Select the results. We use a recursive common table expression to 
    -- get the full path from the start node to the current node. 
    WITH RECURSIVE BacktraceCTE(Id, nm, Distance, Path, NamePath) 
    AS 
    (
    -- Anchor/base member of the recursion, this selects the start node. 
    SELECT n.Id 
    , nd.nm 
    , n.Estimate 
    , Cast(n.Id AS VARCHAR(8000)) AS Path 
    ,Cast(nd.nm AS VARCHAR(8000)) AS NamePath 
    FROM VT_Nodes AS n 
    JOIN T_NODE AS nd 
    ON n.Id = nd.Id 
    WHERE n.Id = StartNode 

    UNION ALL 

    -- Recursive member, select all the nodes which have the previous 
    -- one as their predecessor. Concat the paths together. 
    SELECT n.Id 
    , nd.nm 
    , n.Estimate 
    ,Cast((cte.Path || ',' ||Trim(n.Id)) AS VARCHAR(8000)) 
    ,Cast((cte.NamePath || ',' || nd.nm) AS VARCHAR(8000)) 
    FROM VT_Nodes n 
    JOIN BacktraceCTE AS cte 
    ON n.Predecessor = cte.Id 
    JOIN T_NODE AS nd 
    ON n.Id = nd.Id 
    ) 
    SELECT Id 
    , nm 
    , Distance 
    , Path 
    , NamePath 
    FROM BacktraceCTE 
    WHERE (Id = EndNode OR EndNode IS NULL) -- This kind of where clause can potentially produce 
    ORDER BY Id  -- a bad execution plan, but I use it for simplicity here. 
    ; 

    OPEN CUR1; 
END; 
    DROP TABLE VT_Nodes; 
/* COMMIT TRAN 
    RETURN 0*/ 
END ;