如何在表列中訪問SQL中的varray元素

Question

我試圖找到easy方法來訪問SQL查詢中表列中的varray元素。 varray類型的列標識，但需要將每個元素作爲列呈現給數據庫客戶端。像列名（1）.X，列名（1）.Y，..列名（20）.Y 我們目前使用的功能作爲列返回的數組元素

create or replace function get_point_x(
    p_graph in graph_t, 
    p_point in PLS_INTEGER 
) 
return number 
is 
begin 
    return p_graph(p_point).x; 
exception 
when no_data_found then 
    return to_number(null); 
end get_point_x; 
/

然而，調用此函數的40倍每行大約佔查詢已用時間的40％。所以我想知道是否有一個簡單而高效的SQL替代方案來訪問SQL查詢中的一個元素。我嘗試了下面的方法，但它不比PLSQL函數更有效率！

-- A graph point 
CREATE TYPE point_t AS object(
x number(6,0), 
y number(6,0) 
); 
/

-- Graph can contain up to 20 points, no more 
CREATE TYPE graph_t AS VARRAY(20) OF point_t; 
/

-- Customer graphs 
create table customer_graphs (customer_id number(9,0), graph graph_t); 

insert into customer_graphs values(1, graph_t(point_t(10,10), point_t(20,20), point_t(30,30))); 

insert into customer_graphs values(2, graph_t(point_t(5,5), point_t(10,10), point_t(30,30), point_t(40,31))); 

-- That works but returns graph points as rows 
-- But I need columns x1, y1, ..x20, y20 
select cg.customer_id, g.* from customer_graphs cg, TABLE(cg.graph) g; 

-- Of cource I can pivot but it impacts performance with 40 columns 
select 
    customer_id, 
    max(
    CASE rn 
     WHEN 1 
     THEN x 
    END 
) x_1, 
    max(
    CASE rn 
     WHEN 1 
     THEN y 
    END 
) y_1, 
    max(
    CASE rn 
     WHEN 2 
     THEN x 
    END 
) x_2, 
    max(
    CASE rn 
     WHEN 2 
     THEN y 
    END 
) y_2, 
    -- .. 
    max(
    CASE rn 
     WHEN 20 
     THEN x 
    END 
) x_20, 
    max(
    CASE rn 
     WHEN 20 
     THEN y 
    END 
) y_20 
from (
    select cg.customer_id, g.*, row_number() over(partition by cg.customer_id order by g.x) rn 
    from 
    customer_graphs cg, 
    TABLE(cg.graph) g 
) 
group by customer_id 
; 

-- Is there an easy way to access volumn's varray element in SQL?? 
-- Something like below 
select 
    cg.customer_id, 
    cg.graph, 
-- From this line on it does not work 
cg.graph(1).x x_1, 
cg.graph(1).y y_1, 
-- .. 
cg.graph(20).x x_20, 
cg.graph(20).y y_20 
from customer_graphs cg; 

ORA-00904: "CG"."GRAPH": invalid identifier 
00904. 00000 - "%s: invalid identifier" 
*Cause:  
*Action: 
Error at Line: 258 Column: 2 

有一些有效的SQL解決方案在那裏，我很想念？

預先感謝您

Answer 1

最好的解決辦法是下降的類型和可變數組和存儲在普通表的一切。

如果這不是一個選項，您可以通過將VARRAY封裝在對象類型中並通過成員函數訪問元素來顯着提高性能。這種方法比VARRAY的結果旋轉速度快幾倍。

下面的代碼有點痛苦，但它是一個具有100,000個樣本行的20列全功能測試。

示例模式與VARRAY

CREATE TYPE point_t AS object(
x number(6,0), 
y number(6,0) 
); 

-- Graph can contain up to 20 points, no more 
CREATE TYPE graph_t AS VARRAY(20) OF point_t; 

-- Customer graphs 
create table customer_graphs (customer_id number(9,0), graph graph_t); 

--100K rows, 5.2 seconds. 
begin 
    for i in 1 .. 100000 loop 
     insert into customer_graphs values(i, graph_t(point_t(1,1),point_t(2,2),point_t(3,3),point_t(4,4),point_t(5,5),point_t(6,6),point_t(7,7),point_t(8,8),point_t(9,9),point_t(10,10),point_t(11,11),point_t(12,12),point_t(13,13),point_t(14,14),point_t(15,15),point_t(16,16),point_t(17,17),point_t(18,18),point_t(19,19),point_t(20,20))); 
    end loop; 
    commit; 
end; 
/

begin 
    dbms_stats.gather_table_stats(user, 'CUSTOMER_GRAPHS'); 
end; 
/

示例模式與對象包含VARRAY

--Create type to store and access graph and X and Y elements. 
create or replace type graph_obj as object 
(
    graph graph_t, 
    member function x(p_index number) return number, 
    member function y(p_index number) return number 
); 

create or replace type body graph_obj is 
    member function x(p_index number) return number is 
    begin 
     return graph(p_index).x; 
    end; 

    member function y(p_index number) return number is 
    begin 
     return graph(p_index).y; 
    end; 
end; 
/

-- Customer graphs 2 
create table customer_graphs2(customer_id number(9,0), graph graph_obj); 

--100K rows, 5.54 seconds. 
begin 
    for i in 1 .. 100000 loop 
     insert into customer_graphs2 values(i, graph_obj(graph_t(point_t(1,1),point_t(2,2),point_t(3,3),point_t(4,4),point_t(5,5),point_t(6,6),point_t(7,7),point_t(8,8),point_t(9,9),point_t(10,10),point_t(11,11),point_t(12,12),point_t(13,13),point_t(14,14),point_t(15,15),point_t(16,16),point_t(17,17),point_t(18,18),point_t(19,19),point_t(20,20)))); 
    end loop; 
    commit; 
end; 
/

begin 
    dbms_stats.gather_table_stats(user, 'CUSTOMER_GRAPHS2'); 
end; 
/

VARRAY PIVOT性能

前N行 - 4.5秒。

select customer_id, 
    max(CASE rn WHEN 1 THEN x END) x_1, max(CASE rn WHEN 1 THEN y END) y_1, max(CASE rn WHEN 2 THEN x END) x_2, max(CASE rn WHEN 2 THEN y END) y_2, max(CASE rn WHEN 3 THEN x END) x_3, max(CASE rn WHEN 3 THEN y END) y_3, max(CASE rn WHEN 4 THEN x END) x_4, max(CASE rn WHEN 4 THEN y END) y_4, max(CASE rn WHEN 5 THEN x END) x_5, max(CASE rn WHEN 5 THEN y END) y_5, max(CASE rn WHEN 6 THEN x END) x_6, max(CASE rn WHEN 6 THEN y END) y_6, max(CASE rn WHEN 7 THEN x END) x_7, max(CASE rn WHEN 7 THEN y END) y_7, max(CASE rn WHEN 8 THEN x END) x_8, max(CASE rn WHEN 8 THEN y END) y_8, max(CASE rn WHEN 9 THEN x END) x_9, max(CASE rn WHEN 9 THEN y END) y_9, max(CASE rn WHEN 10 THEN x END) x_10, max(CASE rn WHEN 10 THEN y END) y_10, max(CASE rn WHEN 11 THEN x END) x_11, max(CASE rn WHEN 11 THEN y END) y_11, max(CASE rn WHEN 12 THEN x END) x_12, max(CASE rn WHEN 12 THEN y END) y_12, max(CASE rn WHEN 13 THEN x END) x_13, max(CASE rn WHEN 13 THEN y END) y_13, max(CASE rn WHEN 14 THEN x END) x_14, max(CASE rn WHEN 14 THEN y END) y_14, max(CASE rn WHEN 15 THEN x END) x_15, max(CASE rn WHEN 15 THEN y END) y_15, max(CASE rn WHEN 16 THEN x END) x_16, max(CASE rn WHEN 16 THEN y END) y_16, max(CASE rn WHEN 17 THEN x END) x_17, max(CASE rn WHEN 17 THEN y END) y_17, max(CASE rn WHEN 18 THEN x END) x_18, max(CASE rn WHEN 18 THEN y END) y_18, max(CASE rn WHEN 19 THEN x END) x_19, max(CASE rn WHEN 19 THEN y END) y_19, max(CASE rn WHEN 20 THEN x END) x_20, max(CASE rn WHEN 20 THEN y END) y_20 
from (
    select cg.customer_id, g.*, row_number() over(partition by cg.customer_id order by g.x) rn 
    from 
    customer_graphs cg, 
    TABLE(cg.graph) g 
) 
group by customer_id; 

所有行 - 17秒

select sum(x_1) x 
from 
(
    select customer_id, 
     max(CASE rn WHEN 1 THEN x END) x_1, max(CASE rn WHEN 1 THEN y END) y_1, max(CASE rn WHEN 2 THEN x END) x_2, max(CASE rn WHEN 2 THEN y END) y_2, max(CASE rn WHEN 3 THEN x END) x_3, max(CASE rn WHEN 3 THEN y END) y_3, max(CASE rn WHEN 4 THEN x END) x_4, max(CASE rn WHEN 4 THEN y END) y_4, max(CASE rn WHEN 5 THEN x END) x_5, max(CASE rn WHEN 5 THEN y END) y_5, max(CASE rn WHEN 6 THEN x END) x_6, max(CASE rn WHEN 6 THEN y END) y_6, max(CASE rn WHEN 7 THEN x END) x_7, max(CASE rn WHEN 7 THEN y END) y_7, max(CASE rn WHEN 8 THEN x END) x_8, max(CASE rn WHEN 8 THEN y END) y_8, max(CASE rn WHEN 9 THEN x END) x_9, max(CASE rn WHEN 9 THEN y END) y_9, max(CASE rn WHEN 10 THEN x END) x_10, max(CASE rn WHEN 10 THEN y END) y_10, max(CASE rn WHEN 11 THEN x END) x_11, max(CASE rn WHEN 11 THEN y END) y_11, max(CASE rn WHEN 12 THEN x END) x_12, max(CASE rn WHEN 12 THEN y END) y_12, max(CASE rn WHEN 13 THEN x END) x_13, max(CASE rn WHEN 13 THEN y END) y_13, max(CASE rn WHEN 14 THEN x END) x_14, max(CASE rn WHEN 14 THEN y END) y_14, max(CASE rn WHEN 15 THEN x END) x_15, max(CASE rn WHEN 15 THEN y END) y_15, max(CASE rn WHEN 16 THEN x END) x_16, max(CASE rn WHEN 16 THEN y END) y_16, max(CASE rn WHEN 17 THEN x END) x_17, max(CASE rn WHEN 17 THEN y END) y_17, max(CASE rn WHEN 18 THEN x END) x_18, max(CASE rn WHEN 18 THEN y END) y_18, max(CASE rn WHEN 19 THEN x END) x_19, max(CASE rn WHEN 19 THEN y END) y_19, max(CASE rn WHEN 20 THEN x END) x_20, max(CASE rn WHEN 20 THEN y END) y_20 
    from (
     select cg.customer_id, g.*, row_number() over(partition by cg.customer_id order by g.x) rn 
     from 
     customer_graphs cg, 
     TABLE(cg.graph) g 
    ) 
    group by customer_id 
); 

對象性能

前N行 - 0.4秒

select cg.customer_id, cg.graph.x(1) x_1, cg.graph.y(1) y_1, cg.graph.x(2) x_2, cg.graph.y(2) y_2, cg.graph.x(3) x_3, cg.graph.y(3) y_3, cg.graph.x(4) x_4, cg.graph.y(4) y_4, cg.graph.x(5) x_5, cg.graph.y(5) y_5, cg.graph.x(6) x_6, cg.graph.y(6) y_6, cg.graph.x(7) x_7, cg.graph.y(7) y_7, cg.graph.x(8) x_8, cg.graph.y(8) y_8, cg.graph.x(9) x_9, cg.graph.y(9) y_9, cg.graph.x(10) x_10, cg.graph.y(10) y_10, cg.graph.x(11) x_11, cg.graph.y(11) y_11, cg.graph.x(12) x_12, cg.graph.y(12) y_12, cg.graph.x(13) x_13, cg.graph.y(13) y_13, cg.graph.x(14) x_14, cg.graph.y(14) y_14, cg.graph.x(15) x_15, cg.graph.y(15) y_15, cg.graph.x(16) x_16, cg.graph.y(16) y_16, cg.graph.x(17) x_17, cg.graph.y(17) y_17, cg.graph.x(18) x_18, cg.graph.y(18) y_18, cg.graph.x(19) x_19, cg.graph.y(19) y_19, cg.graph.x(20) x_20, cg.graph.y(20) y_20 
from customer_graphs2 cg; 

所有行 - 2。5秒

select sum(x_1) 
from 
(
    select cg.customer_id, cg.graph.x(1) x_1, cg.graph.y(1) y_1, cg.graph.x(2) x_2, cg.graph.y(2) y_2, cg.graph.x(3) x_3, cg.graph.y(3) y_3, cg.graph.x(4) x_4, cg.graph.y(4) y_4, cg.graph.x(5) x_5, cg.graph.y(5) y_5, cg.graph.x(6) x_6, cg.graph.y(6) y_6, cg.graph.x(7) x_7, cg.graph.y(7) y_7, cg.graph.x(8) x_8, cg.graph.y(8) y_8, cg.graph.x(9) x_9, cg.graph.y(9) y_9, cg.graph.x(10) x_10, cg.graph.y(10) y_10, cg.graph.x(11) x_11, cg.graph.y(11) y_11, cg.graph.x(12) x_12, cg.graph.y(12) y_12, cg.graph.x(13) x_13, cg.graph.y(13) y_13, cg.graph.x(14) x_14, cg.graph.y(14) y_14, cg.graph.x(15) x_15, cg.graph.y(15) y_15, cg.graph.x(16) x_16, cg.graph.y(16) y_16, cg.graph.x(17) x_17, cg.graph.y(17) y_17, cg.graph.x(18) x_18, cg.graph.y(18) y_18, cg.graph.x(19) x_19, cg.graph.y(19) y_19, cg.graph.x(20) x_20, cg.graph.y(20) y_20 
    from customer_graphs2 cg 
); 

Answer 2

設置

CREATE TYPE point_t AS object(
x number(6,0), 
y number(6,0) 
); 
/
-- Graph can contain up to 20 points, no more 
CREATE TYPE graph_t AS VARRAY(20) OF point_t; 
/
-- Customer graphs 
create table customer_graphs (customer_id number(9,0), graph graph_t); 

BEGIN 

    FOR i IN 1 .. 100000 
    LOOP 
    -- build graph as it may contain up to 20 points 

    DECLARE 
     lv_graph graph_t := graph_t(); 
    BEGIN 

     FOR j IN 1..mod(i, 20) + 1 
     LOOP 

     lv_graph.extend(); 
     lv_graph(j) := point_t(i, i); 

     END LOOP; 

     INSERT INTO customer_graphs VALUES (i, lv_graph); 

    END; 

    END LOOP; 

    COMMIT; 

END; 
/

begin 
    dbms_stats.gather_table_stats(user, 'CUSTOMER_GRAPHS'); 
end; 
/

原始PL/SQL函數

create or replace function x(p_graph graph_t, p_index number) return number is 
    begin 
     if p_graph.exists(p_index) then 
      return p_graph(p_index).x; 
     else 
      return to_number(null); 
     end if; 
    end; 
/ 

create or replace function y(p_graph graph_t, p_index number) return number is 
    begin 
     if p_graph.exists(p_index) then 
     return p_graph(p_index).y; 
     else 
      return to_number(null); 
     end if; 
    end; 
/

喬恩海勒建議（略有修改）

我添加了NULL值的測試，因爲圖不總是包含所有20分。

create or replace type graph_obj as object 
(
    graph graph_t, 
    member function x(p_index number) return number, 
    member function y(p_index number) return number 
); 
/

create or replace type body graph_obj is 
    member function x(p_index number) return number is 
    begin 
     if graph.exists(p_index) then 
      return graph(p_index).x; 
     else 
      return to_number(null); 
     end if; 
    end; 

    member function y(p_index number) return number is 
    begin 
     if graph.exists(p_index) then 
     return graph(p_index).y; 
     else 
      return to_number(null); 
     end if; 
    end; 
end; 
/

此應用程序非常陳舊，並被許多其他應用程序使用。我正在編寫另一個應用程序的接口..我可以看到這個應用程序隨着時間的推移如何開發:-)首先使用關係表，然後引入VARRAY，然後嵌套表（我假設當面向對象的範例是花哨和時髦的），現在是很好的舊關係表。我同意使用純關係表更好。

我無法修改該應用程序。所以我創建了graph_obj對象。我需要所有行。我在SQL查詢跑* Plus中與

set timing on 
set arraysize 5000 
set autotrace TRACEONLY statistics 

我沒有不使用SUM（X_1）誘騙，因爲甲骨文是智能不執行等39個電話來計算Y_1，...，x_20，y_20。這就是爲什麼對象方法似乎比關鍵方法更快。

VARRAY透視性能

-- Pivot 13 secs 
select customer_id, 
     max(CASE rn WHEN 1 THEN x END) x_1, max(CASE rn WHEN 1 THEN y END) y_1, max(CASE rn WHEN 2 THEN x END) x_2, max(CASE rn WHEN 2 THEN y END) y_2, max(CASE rn WHEN 3 THEN x END) x_3, max(CASE rn WHEN 3 THEN y END) y_3, max(CASE rn WHEN 4 THEN x END) x_4, max(CASE rn WHEN 4 THEN y END) y_4, max(CASE rn WHEN 5 THEN x END) x_5, max(CASE rn WHEN 5 THEN y END) y_5, max(CASE rn WHEN 6 THEN x END) x_6, max(CASE rn WHEN 6 THEN y END) y_6, max(CASE rn WHEN 7 THEN x END) x_7, max(CASE rn WHEN 7 THEN y END) y_7, max(CASE rn WHEN 8 THEN x END) x_8, max(CASE rn WHEN 8 THEN y END) y_8, max(CASE rn WHEN 9 THEN x END) x_9, max(CASE rn WHEN 9 THEN y END) y_9, max(CASE rn WHEN 10 THEN x END) x_10, max(CASE rn WHEN 10 THEN y END) y_10, max(CASE rn WHEN 11 THEN x END) x_11, max(CASE rn WHEN 11 THEN y END) y_11, max(CASE rn WHEN 12 THEN x END) x_12, max(CASE rn WHEN 12 THEN y END) y_12, max(CASE rn WHEN 13 THEN x END) x_13, max(CASE rn WHEN 13 THEN y END) y_13, max(CASE rn WHEN 14 THEN x END) x_14, max(CASE rn WHEN 14 THEN y END) y_14, max(CASE rn WHEN 15 THEN x END) x_15, max(CASE rn WHEN 15 THEN y END) y_15, max(CASE rn WHEN 16 THEN x END) x_16, max(CASE rn WHEN 16 THEN y END) y_16, max(CASE rn WHEN 17 THEN x END) x_17, max(CASE rn WHEN 17 THEN y END) y_17, max(CASE rn WHEN 18 THEN x END) x_18, max(CASE rn WHEN 18 THEN y END) y_18, max(CASE rn WHEN 19 THEN x END) x_19, max(CASE rn WHEN 19 THEN y END) y_19, max(CASE rn WHEN 20 THEN x END) x_20, max(CASE rn WHEN 20 THEN y END) y_20 
    from (
     select cg.customer_id, g.*, row_number() over(partition by cg.customer_id order by g.x) rn 
     from 
     customer_graphs cg, 
     TABLE(cg.graph) g 
    ) 
    group by customer_id; 

原始PLSQL功能的性能

-- PLSQL 75 secs. 
select cg.customer_id, x(cg.graph,1) x_1, y(cg.graph,1) y_1, x(cg.graph,2) x_2, y(cg.graph,2) y_2, x(cg.graph,3) x_3, y(cg.graph,3) y_3, x(cg.graph,4) x_4, y(cg.graph,4) y_4, x(cg.graph,5) x_5, y(cg.graph,5) y_5, x(cg.graph,6) x_6, y(cg.graph,6) y_6, x(cg.graph,7) x_7, y(cg.graph,7) y_7, x(cg.graph,8) x_8, y(cg.graph,8) y_8, x(cg.graph,9) x_9, y(cg.graph,9) y_9, x(cg.graph,10) x_10, y(cg.graph,10) y_10, x(cg.graph,11) x_11, y(cg.graph,11) y_11, x(cg.graph,12) x_12, y(cg.graph,12) y_12, x(cg.graph,13) x_13, y(cg.graph,13) y_13, x(cg.graph,14) x_14, y(cg.graph,14) y_14, x(cg.graph,15) x_15, y(cg.graph,15) y_15, x(cg.graph,16) x_16, y(cg.graph,16) y_16, x(cg.graph,17) x_17, y(cg.graph,17) y_17, x(cg.graph,18) x_18, y(cg.graph,18) y_18, x(cg.graph,19) x_19, y(cg.graph,19) y_19, x(cg.graph,20) x_20, y(cg.graph,20) y_20 
    from customer_graphs cg; 

對象性能

-- Object 83 secs, 6 times slower than pivot query 
-- I assume that additional 8 secs were caused by creating objects on the fly 

    select cg.customer_id, cg.graph.x(1) x_1, cg.graph.y(1) y_1, cg.graph.x(2) x_2, cg.graph.y(2) y_2, cg.graph.x(3) x_3, cg.graph.y(3) y_3, cg.graph.x(4) x_4, cg.graph.y(4) y_4, cg.graph.x(5) x_5, cg.graph.y(5) y_5, cg.graph.x(6) x_6, cg.graph.y(6) y_6, cg.graph.x(7) x_7, cg.graph.y(7) y_7, cg.graph.x(8) x_8, cg.graph.y(8) y_8, cg.graph.x(9) x_9, cg.graph.y(9) y_9, cg.graph.x(10) x_10, cg.graph.y(10) y_10, cg.graph.x(11) x_11, cg.graph.y(11) y_11, cg.graph.x(12) x_12, cg.graph.y(12) y_12, cg.graph.x(13) x_13, cg.graph.y(13) y_13, cg.graph.x(14) x_14, cg.graph.y(14) y_14, cg.graph.x(15) x_15, cg.graph.y(15) y_15, cg.graph.x(16) x_16, cg.graph.y(16) y_16, cg.graph.x(17) x_17, cg.graph.y(17) y_17, cg.graph.x(18) x_18, cg.graph.y(18) y_18, cg.graph.x(19) x_19, cg.graph.y(19) y_19, cg.graph.x(20) x_20, cg.graph.y(20) y_20 
    from (
    select cgi.customer_id, graph_obj(cgi.graph) graph 
    from customer_graphs cgi 
    ) cg 
;