MySQL遞歸循環檢測程序

Question

我有以下程序，旨在檢測無向圖中的週期，其中包含邊（單邊）和邊集（邊集）。還有兩個參數：left_set（意思是存儲必須傳遞到遞歸中的邊）和循環（這是一個布爾值，最終確定圖是否是循環的）

由於某些原因，不過去的第一遞歸在這裏工作是解釋細節的註釋代碼：

以下功能實施了本人在MYSQL（以避免混淆）：

-concat_set（）：返回兩套的連接計算錯位'，'在空集的情況下

-remove_first（）：刪除從設置

-get_left_node（）/ get_right_node第一構件：返回邊緣的節點，所述邊緣之間的分隔符是「：」這樣的邊緣看起來像這樣'12：15'

CREATE PROCEDURE `is_cyclic`(
IN `singleedge` VARCHAR(15), 
IN `edgeset` VARCHAR(1024), 
IN 'left_set' VARCHAR(512), 
OUT `cyclic` BOOLEAN) 

BEGIN 
DECLARE se_left VARCHAR(5); 
DECLARE es_left VARCHAR(5); 
DECLARE se_right VARCHAR(5); 
DECLARE es_right VARCHAR(5); 
Call get_left_node(singleedge, se_left); 
Call get_left_node(SUBSTRING_INDEX(edgeset, ',', 1), es_left); 
Call get_right_node(singleedge, se_right); 
Call get_right_node(SUBSTRING_INDEX(edgeset, ',', 1), es_right); 



--is edgeset emptY? 
    IF LENGTH(edgeset)= 0 AND LENGTH(left_set) = 0 THEN 
     BEGIN 

      SET cyclic= false; 

     END;  

--are singeeledge and first edge in edgeset the same?   
    ELSEIF ((se_left = es_left 
     OR se_left= es_right) 
     AND(se_right = es_left 
     OR se_right = es_right)) THEN 
        BEGIN 
      set cyclic= true; 
         END; 


--do singleedge and first edge in edgeset share any vertices?  
    ELSEIF se_left = es_left 
     OR se_left= es_right 
     OR se_right = es_left 
     OR se_right = es_right 
     THEN 
     --check for all possiblities 
      BEGIN 

       --if left vertex of singleedge and left vertex of current edge in front of edgeset are the same    
       IF se_left=es_left THEN 
            BEGIN 
            --test if the edge of combined uncommon vertices (forming concat(se_right,':',es_right)) exists in the remaining edgeset concatanated with the left_set 
            CALL is_cyclic(concat(se_right,':',es_right),concat_set(left_set,remove_first(edgeset)), '', cyclic); 
            --if the recursion returns cyclic=false, then remove the considered edge from edgeset and continue trying to match the original singleedge with the rest of edgeset 
            IF cyclic=false THEN 
             CALL is_cyclic(singleedge, remove_first(edgeset), left_set, cyclic); 
             END IF; 
            END; 
       ELSEIF se_left= es_right THEN 
            BEGIN 
            CALL is_cyclic(concat(se_right,':',es_left), concat_set(left_set, remove_first(edgeset)), '', cyclic); 
            IF cyclic=false THEN 
             CALL is_cyclic(singleedge, remove_first(edgeset), left_set, cyclic); 
            END IF; 
            END; 
       ELSEIF se_right=es_left THEN 
            BEGIN 
            CALL is_cyclic(concat(se_left,':',es_right), concat_set(left_set, remove_first(edgeset)), '', cyclic); 
            IF cyclic=false THEN 
             CALL is_cyclic(singleedge, remove_first(edgeset), left_set, cyclic); 
            END IF; 
            END; 
       ELSE 
            BEGIN 
            CALL is_cyclic(concat(se_left,':',es_left), concat_set(left_set, remove_first(edgeset)), '', cyclic); 
            IF cyclic=false THEN 
             CALL is_cyclic(singleedge, remove_first(edgeset), left_set, cyclic); 
            END IF; 
             END; 
           END IF; 


      END;  


     ELSE 
      BEGIN 
       --if the current edge being considered from the edgeset does not contain any vertex in common with singleedge, set it aside into left_set and call is_cyclic recurisvely with the edge removed 
       SET left_set = concat_set(left_set, SUBSTRING_INDEX(edgeset, ',', 1)); 
       CALL is_cyclic(singleedge, remove_first(edgeset), left_set, cyclic); 
       END; 

    END IF; 
END 

Answer 1

嘗試重置這個MySQL變量：max_sp_recursion_depth，thread_stack

SET SESSION max_sp_recursion_depth = 10; 
SET SESSION thread_stack = 250000; 

上面的命令執行調用你的程序之後。連續執行兩個語句。 根據您的要求增加thread_stack變量的大小。