我使用嵌套表来收集table.And的数据,使用这些数据插入到另一个table.Below中是我正在使用的代码。我对批量收集的容量感到好奇。
begin
type bandtvarray is table of BANDWISETVCOVERAGE%rowtype;
Band_arr bandtvarray;
FOR j IN 1 .. 24 LOOP
--
DELETE from BANDWISETVCOVERAGE
WHERE trunc(CREATEDDATE)<trunc(sysdate-60)
AND ROWNUM<1000000
returning BANDWISETVCOVERAGEID_PK
BULK COLLECT into Band_arr;
--
forall i in 1 .. Band_arr.count
insert into ARC_BANDWISETVCOVERAGE
values Band_arr(i);
Band_arr.DELETE();
commit;
--
END LOOP;
发布于 2018-06-02 03:47:41
简短的答案是,除了可用的系统内存之外,确实没有限制,但我认为您问错了问题。正确的问题是:用于批量绑定的合适大小是多少?确实没有确切的数字,但有几件事需要考虑:
我个人的规则是大约100到250行是一个很好的大小。您可以自己测试一下,当集合变得非常大时,性能实际上会变得更差。您希望选择一个运行良好且使用最少内存的数字:我下面的测试显示,即使是50也是一个足够好的值。
DROP TABLE t;
DROP TABLE v;
CREATE TABLE t AS
SELECT * FROM all_objects
CROSS JOIN (SELECT LEVEL FROM dual CONNECT BY LEVEL <= 10);
SELECT COUNT(*) FROM t;
-- 770260
CREATE TABLE v AS SELECT * FROM t WHERE 0 = 1;
DECLARE
TYPE t_tab IS TABLE OF t%ROWTYPE;
x_tab t_tab;
CURSOR c IS
SELECT *
FROM t;
c_bulk_size INTEGER := 50000;
v_start TIMESTAMP(9) := current_timestamp;
BEGIN
OPEN c;
LOOP
FETCH c BULK COLLECT
INTO x_tab LIMIT c_bulk_size;
IF x_tab.count > 0 THEN
FORALL i IN x_tab.first .. x_tab.last
INSERT INTO v
VALUES x_tab
(i);
END IF;
EXIT WHEN x_tab.count < c_bulk_size;
END LOOP;
dbms_output.put_line((current_timestamp - v_start) || ' size ' ||
c_bulk_size);
CLOSE c;
ROLLBACK;
END;
/
-- +000000000 00:00:11.696873000 size 50
-- +000000000 00:00:12.692300000 size 50
-- +000000000 00:00:11.634849000 size 50
-- +000000000 00:00:12.770239000 size 100
-- +000000000 00:00:11.268332000 size 100
-- +000000000 00:00:11.793120000 size 100
-- +000000000 00:00:11.400098000 size 250
-- +000000000 00:00:10.625674000 size 250
-- +000000000 00:00:11.783102000 size 250
-- +000000000 00:00:09.490830000 size 500
-- +000000000 00:00:10.411275000 size 500
-- +000000000 00:00:11.713433000 size 500
-- +000000000 00:00:09.140556000 size 1000
-- +000000000 00:00:12.459841000 size 1000
-- +000000000 00:00:09.132134000 size 1000
-- +000000000 00:00:10.188990000 size 10000
-- +000000000 00:00:09.758166000 size 10000
-- +000000000 00:00:10.685548000 size 10000
-- +000000000 00:00:19.255858000 size 50000
-- +000000000 00:00:20.929404000 size 50000
-- +000000000 00:00:24.243393000 size 50000
我希望这能帮到你。如果你对批量收集限制进行一些搜索,互联网上有很多关于这方面的文章。在AskTom上有几个值得一读。
https://stackoverflow.com/questions/50137545
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