如何創建Postgres的臨時緩存/桌，持續查詢的時間

我有一個非常昂貴的PLSQL函數，做了很多遞歸運算處理的查詢：如何創建Postgres的臨時緩存/桌，持續查詢的時間

SELECT a, b, expensive_recursion(c, d, e) FROM my_table

功能expensive_recursion（）有PLPGSQL這樣的：

CREATE OR REPLACE FUNCTION expensive_recursion(col varchar, parent varchar, date varchar) 
RETURNS integer AS 
$BODY$ 
DECLARE 
    _value integer; 
    _rec record; 
BEGIN 

    -- get the value for the current parent that matches the range 
    EXECUTE 'SELECT value_'||col||' FROM foo WHERE foo.id = '||quote_literal(parent)||' AND foo.range = '||quote_literal(range) INTO _value; 


    -- get all children of parent and sum their values 
    FOR rec IN EXECUTE 'SELECT child FROM relationships WHERE parent = '||quote_literal(parent) LOOP 
    _value = _value + expensive_recursion(col, rec.child, range); 
    END LOOP; 
    RETURN _value; 

END; 
$BODY$ 
LANGUAGE plpgsql STABLE COST 1000;

雖然這工作，我想啓用緩存，不僅對當前行多數民衆贊成在遞歸，但對當前查詢中的所有行，並有一次查詢已完全執行緩存清除。

例如，對於一些僞代碼的原始功能： CREATE OR REPLACE FUNCTION expensive_recursion（COL VARCHAR，父VARCHAR，範圍VARCHAR） RETURNS整數AS $ BODY $ DECLARE _value整數; _rec記錄; BEGIN

-- pseudo-code to check the cache and get the cached value or insert into cache 
    IF parent AND range IN cache 
    RETURN SELECT value FROM cache WHERE cache.parent = parent and cache.range = range; 
    END IF; 

    -- get the value for the current parent that matches the range 
    EXECUTE 'SELECT value_'||col||' FROM foo WHERE foo.id = '||quote_literal(parent)||' AND foo.range = '||quote_literal(range) INTO _value; 


    -- get all children of parent and sum their values 
    FOR rec IN EXECUTE 'SELECT child FROM relationships WHERE parent = '||quote_literal(parent) LOOP 
    _value = _value + expensive_recursion(col, rec.child, range); 
    END LOOP; 

    -- put new value in cache 
    INSERT INTO cache (value, parent, range) VALUES (_value, parent, range); 

    -- final value with sum for parent and its children 
    RETURN _value; 
END; 
$BODY$ 
LANGUAGE plpgsql STABLE COST 1000;

有沒有辦法做到這一點，必須創建緩存/刪除？我可以使用臨時表或者我在plpgsql函數中管理的一些結構/類型。訣竅是多個用戶可以執行此功能，並且出於應用程序特定的原因，緩存不能跨查詢共享。

來源

2014-01-21 user1661467