如何优化使用游标的PL/SQL代码

问题描述

我正在尝试优化一个运行了大约 3 小时的查询以获取/更新 280 万条记录。代码使用游标，我们需要更新整个 280 万条记录。我尝试使用批量收集修改查询，但我认为它没有多大帮助。有人可以告诉我我还能做些什么来优化代码。老实说，即使使用批量收集，我也不认为它会更好......我正在使用 oracle19c

旧代码是：

DECLARE
    CURSOR PROVNUMCURSOR
    IS
      SELECT DISTINCT RCRD_NBR,ID,Entity FROM SPSMDMRW.GTT_SCW_PROFILE_INTRM ;
    v_FirstRow SPSMDMRW.GTT_SCW_PROFILE_INTRM.RCRD_NBR%type;
    v_ID SPSMDMRW.GTT_SCW_PROFILE_INTRM.ID%type;
    v_Entity SPSMDMRW.GTT_SCW_PROFILE_INTRM.Entity%type;
  BEGIN
    OPEN PROVNUMCURSOR;
    --v_FirstRow:=0;v_ID:=0;v_Entity:='0';
    FETCH PROVNUMCURSOR
    INTO v_FirstRow,v_ID,v_Entity;
    WHILE PROVNUMCURSOR%FOUND
    LOOP
      SELECT
        CASE
          WHEN v_ID = v_EndRow
          THEN v_MaxRow
          ELSE
            (SELECT RCRD_NBR-1 FROM SPSMDMRW.GTT_SCW_PROFILE_INTRM WHERE ID = v_ID+1
            )
        END
      INTO v_LastRow
      FROM dual;
      IF v_Entity = '3' THEN
        UPDATE SPSMDMRW.GTT_SCW_SSB_SC_PDF a
        SET ProvNum = LTRIM(RTRIM(TO_CHAR(SUBSTR(Column0,1,13))))
          ||'I'
        WHERE RCRD_NBR BETWEEN v_FirstRow AND v_LastRow;
      ELSE
        IF v_Entity = '4' THEN
          UPDATE SPSMDMRW.GTT_SCW_SSB_SC_PDF a
          SET ProvNum = LTRIM(RTRIM(TO_CHAR(SUBSTR(Column0,13))))
            || 'II'
          WHERE RCRD_NBR BETWEEN v_FirstRow AND v_LastRow;
        ELSE
          UPDATE SPSMDMRW.GTT_SCW_SSB_SC_PDF a
          SET ProvNum = LTRIM(RTRIM(TO_CHAR(SUBSTR(Column0,13))))
          WHERE RCRD_NBR BETWEEN v_FirstRow AND v_LastRow;
        END IF;
      END IF;
      FETCH PROVNUMCURSOR INTO v_FirstRow,v_Entity;
      EXIT
    WHEN PROVNUMCURSOR%NOTFOUND;
    END LOOP;
    --END;
    CLOSE PROVNUMCURSOR;
  END;

我修改的代码如下：

DECLARE
    CURSOR PROVNUMCURSOR
    IS
      SELECT DISTINCT RCRD_NBR,Entity
      FROM SPSMDMRW.GTT_SCW_PROFILE_INTRM_TEST ;
  type v_ID_type
IS
  TABLE OF SPSMDMRW.GTT_SCW_PROFILE_INTRM_TEST.ID%type;
type v_Entity_type
IS
  TABLE OF SPSMDMRW.GTT_SCW_PROFILE_INTRM_TEST.Entity%type;
type v_FirstRow_type
IS
  TABLE OF SPSMDMRW.GTT_SCW_PROFILE_INTRM_TEST.RCRD_NBR%type;
  v_FirstRow v_FirstRow_type;
  v_ID v_ID_type;
  v_Entity v_Entity_type;
  c_limit PLS_INTEGER := 100;
BEGIN
  OPEN PROVNUMCURSOR;
  --v_FirstRow:=0;v_ID:=0;v_Entity:='0';
  LOOP
    FETCH PROVNUMCURSOR bulk collect INTO v_FirstRow,v_Entity LIMIT C_LIMIT;
    EXIT
  WHEN V_FIRSTROW.COUNT = 0;
    --dbms_output.put_line(V_FIRSTROW.COUNT);
    FOR INDX IN 1..V_FIRSTROW.COUNT
    LOOP
      --      dbms_output.put_line(1);
      SELECT
        CASE
          WHEN v_ID(INDX) = v_EndRow
          THEN v_MaxRow
          ELSE
            (SELECT RCRD_NBR-1
            FROM SPSMDMRW.GTT_SCW_PROFILE_INTRM_TEST
            WHERE ID = v_ID(INDX)+1
            )
        END
      INTO v_LastRow
      FROM dual;
      IF v_Entity(INDX) = '3' THEN
        UPDATE SPSMDMRW.GTT_SCW_SSB_SC_PDF_TEST a
        SET ProvNum = LTRIM(RTRIM(TO_CHAR(SUBSTR(Column0,13))))
          ||'I'
        WHERE RCRD_NBR BETWEEN v_FirstRow(INDX) AND v_LastRow;
      ELSIF v_Entity(INDX) = '4' THEN
          --DBMS_OUTPUT.PUT_LINE(v_entity || ' First Row '|| v_FirstRow || ' Last row '||v_LastRow);
          UPDATE SPSMDMRW.GTT_SCW_SSB_SC_PDF_TEST a
          SET ProvNum = LTRIM(RTRIM(TO_CHAR(SUBSTR(Column0,13))))
            || 'II'
          WHERE RCRD_NBR BETWEEN v_FirstRow(INDX) AND v_LastRow;
        ELSE
         -- DBMS_OUTPUT.PUT_LINE(v_entity || ' First Row '|| v_FirstRow || ' Last row '||v_LastRow);
          UPDATE SPSMDMRW.GTT_SCW_SSB_SC_PDF_TEST a
          SET ProvNum = LTRIM(RTRIM(TO_CHAR(SUBSTR(Column0,13))))
          WHERE RCRD_NBR BETWEEN v_FirstRow(INDX) AND v_LastRow;
        END IF;
     END LOOP;
  END LOOP;
  CLOSE PROVNUMCURSOR;
END;

Sample data:
RCRD_NBR    FILE_NM       PROVNUM   ID  ENTITY
225184      sample.txt              1681    2
225241      sample.txt              1682    3
225352      sample.txt              1683    4
225436      sample.txt              1684    5
225493      sample.txt               1685   2

解决方法

如果没有任何样本数据，也不知道逻辑，就很难提供解决方案。我认为这可以通过一个朝着这样的方向发展的语句来完成：

UPDATE SPSMDMRW.GTT_SCW_SSB_SC_PDF a SET ProvNum =
with t as
    (SELECT DISTINCT
       RCRD_NBR as FirstRow,LEAD(RCRD_NBR,1) -1 OVER (ORDER BY ID) AS LastRow,CASE Entity
           when '3' then TRIM(SUBSTR(Column0,1,13))||'I'
           when '4' then TRIM(SUBSTR(Column0,13))||'II'
           else TRIM(SUBSTR(Column0,13))
       end case as ProvNum
    FROM SPSMDMRW.GTT_SCW_PROFILE_INTRM)
SELECT t.ProvNum
from t
where a.RCRD_NBR BETWEEN FirstRow AND LastRow;