Question

我在java程序中使用以下函数将列从临时表复制到主表。

FUNCTION TEST(TBL_NAME VARCHAR2, TMP_TBL_NAME VARCHAR2, ID_COL VARCHAR2, REQ_COL VARCHAR2, BATCH_SIZE NUMBER) RETURN NUMBER AS
BEGIN
EXECUTE IMMEDIATE 'SELECT COUNT(1) FROM ' || TMP_TBL_NAME INTO TOTAL_RECORDS;
OFFSET := 0;
WHILE OFFSET < TOTAL_RECORDS
LOOP
  MAX_RESULTS := OFFSET + BATCH_SIZE;
  EXECUTE IMMEDIATE 'SELECT ' || ID_COL || ', ' || REQ_COL || ' FROM ' || TMP_TBL_NAME || ' WHERE SEQ_NBR BETWEEN :OFFSET AND :MAX_RESULTS' BULK COLLECT INTO SEQ_IDS, REQ_COL_VALUESS USING OFFSET, MAX_RESULTS;
  FORALL IND IN SEQ_IDS.FIRST .. SEQ_IDS.LAST
    EXECUTE IMMEDIATE 'UPDATE ' || TBL_NAME || ' SET ' || REQ_COL || ' = :REQ_COL_VAL WHERE ' || ID_COL || ' = :ID_COL_VAL' USING REQ_COL_VALUESS(IND), SEQ_IDS(IND);
  OFFSET := MAX_RESULTS;
  COMMIT;
END LOOP;
RETURN 0;
EXCEPTION
WHEN OTHERS THEN
  RAISE CUST_EXCEPTION; 
END;

预期的结果是当我运行batch_size为100000时，对于每次提交，必须更新100000条记录，因为上面使用的id_col是主键。在运行java程序之后，当我在主表中检查更新时，我可以看到正在更新的批次6469或80148的记录。

临时表中有大约1000万条记录。如果我删除了forall update语句，我将以适当的批量大小迭代数据。

可以澄清一下为什么会发生这种情况

Answer 1

1）您的临时表中有多少条记录？

2）为什么你不使用sys_refcursor和bulk collect with limit？

declare 
 v_cursor sys_refcursor; 
 res1 sys.DBMS_DEBUG_VC2COLL; -- - predefined collection in oracle 
 res2 sys.DBMS_DEBUG_VC2COLL;
 v_batch_size pls_integer := 50;
begin 
 open v_cursor for 'Select 1,2 from dual connect by level < 10000';
 loop
 fetch v_cursor bulk collect into res1,res2 limit v_batch_size;
 exit when res1.count =0;
    dbms_output.put_line(res1.count);
  -- forall ind in res1.first .. res1.last loop e.g 
  -- commit;
 end loop;
  close v_cursor;
end;

Answer 2

-- first iteration offset= 0 , max_result = 10 
-- v_batch_size = 10
-- offset := 0 
--  MAX_RESULTS := 10 
select seg from ( Select level seg from dual connect by level < 1000)  where seg between 0 and 10;
-- secound iteration 
-- v_batch_size = 10
-- offset := 10 
--  MAX_RESULTS := 20 
select seg from ( Select level seg from dual connect by level < 1000) where seg between 10 and 20;

在PLSQL循环中提交以进行更新

2 个答案: