记一次全局分区索引update调优

原始SQL：

CREATE OR REPLACE PROCEDURE sp_upd_suppressed_emails
(
  A_LIMIT_BULK IN PLS_INTEGER DEFAULT 2000,
  A_COMMIT_AFTER IN PLS_INTEGER DEFAULT 2000
) is

  v_operation Varchar2(20) := 'START';
  v_last         PLS_INTEGER;   
  v_start        PLS_INTEGER;   
  v_end          PLS_INTEGER;  
  l_row          PLS_INTEGER;
  
  CURSOR curs_contact IS SELECT id FROM contact
  WHERE active_ind = 2 and suppress_flag = 'Y' and bounce_flag = 'Y' 
  and consumer_id in (select id from consumers where login_name IN ('ASPIRAFOCUS', 'CDFW', 'PSACSFSUSR') ) 
  and  email is not null ORDER BY id; 
  
  TYPE contactId IS RECORD ( id contact.id%TYPE); 
	 
  TYPE v_contactId_tbl IS TABLE OF contactId INDEX BY PLS_INTEGER;
  
  v_contact v_contactId_tbl;    
   
BEGIN
    
    DBMS_OUTPUT.PUT_LINE ('start reading data..' );
    v_operation := 'BEFORE OPEN';
	OPEN curs_contact;	

	LOOP

		v_operation := 'BEFORE FETCH';
		FETCH curs_contact BULK COLLECT INTO v_contact LIMIT A_LIMIT_BULK;
		v_operation := 'AFTER FETCH';

		EXIT WHEN v_contact.COUNT = 0;	

		v_start := 1;   
		v_last := v_contact.COUNT; 	
		l_row := 0;		

		LOOP			
			DBMS_OUTPUT.PUT_LINE ('LOOP 2 top ');
			EXIT WHEN v_start > v_last;
			v_end := LEAST (v_start + A_COMMIT_AFTER - 1, v_last);		
            DBMS_OUTPUT.PUT_LINE ('LOOP 2 v_start ' || v_start || ' end ' || v_end );	
			BEGIN				
				v_operation := 'UPDATE_LOAD';
				FORALL i IN v_start .. v_end 
                UPDATE contact SET active_ind = 1, suppress_flag = 'N', bounce_flag = 'N'  WHERE id = v_contact (i).id;				
            END;
			DBMS_OUTPUT.PUT_LINE ('after forall start ' || v_start || ' end ' || v_end );
            COMMIT;
			v_start := v_end + 1;         
		END LOOP;
		DBMS_OUTPUT.PUT_LINE ('LOOP 2 bottom v_start ' || v_start || ' end ' || v_end );
        COMMIT;
	END LOOP;
	DBMS_OUTPUT.PUT_LINE ('stop reading data..' );
    
    EXCEPTION 
	WHEN OTHERS THEN	
		DBMS_OUTPUT.PUT_LINE ('Exception:Others-> v_operation = ' || v_operation || ', rowcount # ' || l_row || ' SQLCODE ' || SQLCODE || ' ERR_MSG = ' || SUBSTR(SQLERRM, 1, 500) );	

END sp_upd_suppressed_emails;

原始SQL在执行过程中经过几小时未完成，查看sql统计信息：

Stat Name	Statement Total	Per Execution	% Snap Total
Elapsed Time (ms)	2,997,435	187,339.68	53.56
CPU Time (ms)	2,896,748	181,046.72	65.48
Executions	16
Buffer Gets	521,592,791	32,599,549.44	69.21
Disk Reads	10,974	685.88	1.12
Parse Calls	1	0.06	0.00
Rows	32,000	2,000.00
User I/O Wait Time (ms)	2,525
Cluster Wait Time (ms)	1,146
Application Wait Time (ms)	4
Concurrency Wait Time (ms)	1
Invalidations	0
Version Count	1
Sharable Mem(KB)	51

Back to Plan 1(PHV: 3689516641)

Execution Plan

Id	Operation	Name	Rows	Bytes	Cost (%CPU)	Time	Pstart	Pstop
0	UPDATE STATEMENT				16798 (100)
1	UPDATE	CONTACT
2	PARTITION RANGE ALL		1	51	16798 (1)	00:00:01	1	1048575
3	PARTITION HASH SINGLE		1	51	16798 (1)	00:00:01	KEY	KEY
4	TABLE ACCESS FULL	CONTACT	1	51	16798 (1)	00:00:01

表数据量非常大，根据created_date时间字段分区，ID字段进行子hash分区，上面建立了基于ID字段的global hash分区索引。

从上面情况看出，原始SQL分批2000个ID进行批量update，但执行计划走的是TABLE ACCESS FULL, 并且进行了分区的PRATITION RANGE ALL操作，可以看出2000条记录的批量更新由于不能利用global hash分区索引进行检索，主要原因是由于hash分区适用于等值操作，对于范围或者批量操作，可能遍历很多hash分区，导致结果不如TABLE ACCESS FULL。

针对这种情况，根据业务逻辑，将批量条件从ID改成其他非global hash索引列，执行时间降低为5分钟。

​CREATE OR REPLACE PROCEDURE sp_upd_suppressed_emails
(
    A_LIMIT_BULK IN PLS_INTEGER DEFAULT 2000,
    A_COMMIT_AFTER IN PLS_INTEGER DEFAULT 2000
) is

    v_operation Varchar2(20) := 'START';
    v_last         PLS_INTEGER;
    v_start        PLS_INTEGER;
    v_end          PLS_INTEGER;
    l_row          PLS_INTEGER;

    CURSOR curs_contact IS SELECT distinct email FROM contact
                           WHERE active_ind = 2 and suppress_flag = 'Y' and bounce_flag = 'Y'
                             and consumer_id in (select id from consumers where login_name IN ('ASPIRAFOCUS', 'CDFW', 'PSACSFSUSR') )
                             and  email is not null ORDER BY email;

    TYPE contactId IS RECORD ( email contact.email%TYPE);

    TYPE v_contactId_tbl IS TABLE OF contactId INDEX BY PLS_INTEGER;

    v_contact v_contactId_tbl;

    v_upd_date date ;

BEGIN

    DBMS_OUTPUT.PUT_LINE ('start reading data..' );
    v_operation := 'BEFORE OPEN';

    select sysdate into v_upd_date from dual;

    OPEN curs_contact;

    LOOP

        v_operation := 'BEFORE FETCH';
        FETCH curs_contact BULK COLLECT INTO v_contact LIMIT A_LIMIT_BULK;
        v_operation := 'AFTER FETCH';

        EXIT WHEN v_contact.COUNT = 0;

        v_start := 1;
        v_last := v_contact.COUNT;
        l_row := 0;

        LOOP
            DBMS_OUTPUT.PUT_LINE ('LOOP 2 top ');
            EXIT WHEN v_start > v_last;
            v_end := LEAST (v_start + A_COMMIT_AFTER - 1, v_last);
            DBMS_OUTPUT.PUT_LINE ('LOOP 2 v_start ' || v_start || ' end ' || v_end );
            BEGIN
                v_operation := 'UPDATE_LOAD';
                FORALL i IN v_start .. v_end
                    UPDATE contact SET active_ind = 1, suppress_flag = 'N', bounce_flag = 'N' , modified_date =  v_upd_date
                    WHERE email = v_contact (i).email
                      and   active_ind = 2 and suppress_flag = 'Y' and bounce_flag = 'Y'
                      and consumer_id in (select id from consumers where login_name IN ('ASPIRAFOCUS', 'CDFW', 'PSACSFSUSR') )  ;
            END;
            DBMS_OUTPUT.PUT_LINE ('after forall start ' || v_start || ' end ' || v_end );
            COMMIT;
            v_start := v_end + 1;
        END LOOP;
        DBMS_OUTPUT.PUT_LINE ('LOOP 2 bottom v_start ' || v_start || ' end ' || v_end );
        COMMIT;
    END LOOP;
    DBMS_OUTPUT.PUT_LINE ('stop reading data..' );

EXCEPTION
    WHEN OTHERS THEN
        DBMS_OUTPUT.PUT_LINE ('Exception:Others-> v_operation = ' || v_operation || ', rowcount # ' || l_row || ' SQLCODE ' || SQLCODE || ' ERR_MSG = ' || SUBSTR(SQLERRM, 1, 500) );

END sp_upd_suppressed_emails;