一个通过dblink查询的优化案例（去掉filter）
原语句如下
EXPLAIN PLAN FOR SELECT a.*, b.rkids
FROM (SELECT gys.khbh,
gys.khmc,
wz.wzzbm,
wz.wzmbm,
wz.wzmc,
wz.wzgg,
a.sl,
wz.jldw,
wz.wzflmbm,
a.sl * wz.wzflmbm jhje
FROM wz@dblink wz,
gys@dblink gys,
(SELECT m.khbh,
d.wzzbm,
SUM(CASE m.rkzt
WHEN '2' THEN
d.xysl
ELSE
-1 * d.xysl
END) sl
FROM m@dblink m, d@dblink d
WHERE m.rkid = d.rkid
AND m.rkzt IN (2, 3)
AND m.ssny < '201311'
GROUP BY m.khbh, d.wzzbm) a
WHERE a.sl > 0
AND gys.khbh = a.khbh
AND wz.wzzbm = a.wzzbm/*
and gys.khbh='00342'
and wz.wzzbm='07524'*/) a,
(SELECT m.khbh, d.wzzbm, wmsys.wm_concat(m.rkid) rkids
FROM m@dblink m, d@dblink d
WHERE m.rkid = d.rkid/*
and m.khbh='00342'
and d.wzzbm='07524'*/
AND m.rkzt = 2
AND m.ssny < '201311'
AND m.zxdid IS NULL
AND (NOT EXISTS (SELECT 1
FROM m@dblink m1, d@dblink d1
WHERE m1.rkid = d1.rkid
AND m1.zxdid = m.rkid
AND d1.wzzbm = d.wzzbm
AND m1.rkzt = 3) OR
(SELECT SUM(d1.xysl)
FROM m@dblink m1, d@dblink d1
WHERE m1.rkid = d1.rkid
AND m1.zxdid = m.rkid
AND d1.wzzbm = d.wzzbm
AND m1.rkzt = 3) < d.xysl)
GROUP BY m.khbh, d.wzzbm) b
WHERE a.khbh = b.khbh(+)
AND a.wzzbm = b.wzzbm(+);
1 Plan hash value: 2646510213
2
3 ---------------------------------------------------------------------------------------------------
4 | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Inst |IN-OUT|
5 ---------------------------------------------------------------------------------------------------
6 | 0 | SELECT STATEMENT | | 702K| 1445M| 236 (15)| 00:00:03 | | |
7 |* 1 | HASH JOIN RIGHT OUTER| | 702K| 1445M| 236 (15)| 00:00:03 | | |
8 | 2 | VIEW | | 1 | 2018 | 128 (8)| 00:00:02 | | |
9 | 3 | SORT GROUP BY | | 1 | 67 | 128 (8)| 00:00:02 | | |
10 |* 4 | FILTER | | | | | | | |
11 | 5 | REMOTE | | 1 | 38 | 124 (7)| 00:00:02 | WN | R->S |
12 | 6 | NESTED LOOPS | | 2 | 84 | 12 (0)| 00:00:01 | | |
13 | 7 | REMOTE | MP_RKDJWZ | 8 | 128 | 4 (0)| 00:00:01 | WN | R->S |
14 | 8 | REMOTE | MP_RKDJ | 1 | 26 | 1 (0)| 00:00:01 | WN | R->S |
15 | 9 | SORT AGGREGATE | | 1 | 55 | | | | |
16 | 10 | NESTED LOOPS | | 2 | 110 | 12 (0)| 00:00:01 | | |
17 | 11 | REMOTE | MP_RKDJWZ | 8 | 232 | 4 (0)| 00:00:01 | WN | R->S |
18 | 12 | REMOTE | MP_RKDJ | 1 | 26 | 1 (0)| 00:00:01 | WN | R->S |
19 | 13 | VIEW | | 702K| 93M| 97 (16)| 00:00:02 | | |
20 | 14 | REMOTE | | | | | | WN | R->S |
21 ---------------------------------------------------------------------------------------------------
22
23 Predicate Information (identified by operation id):
24 ---------------------------------------------------
25
26 1 - access("A"."KHBH"="B"."KHBH"(+) AND "A"."WZZBM"="B"."WZZBM"(+))
27 4 - filter( NOT EXISTS (SELECT 0 FROM "A1", "A2" WHERE "M1"."ZXDID"=:B1 AND
28 TO_NUMBER("M1"."RKZT")=3 AND "M1"."RKID"="D1"."RKID" AND "D1"."WZZBM"=:B2) OR "D"."XYSL">
29 (SELECT SUM("D1"."XYSL") FROM "A1", "A2" WHERE "M1"."ZXDID"=:B3 AND
30 TO_NUMBER("M1"."RKZT")=3 AND "M1"."RKID"="D1"."RKID" AND "D1"."WZZBM"=:B4))
31
32 Remote SQL Information (identified by operation id):
33 ----------------------------------------------------
34
35 5 - SELECT "A1"."RKID","A1"."RKID","A1"."RKID","A1"."RKID","A1"."RKZT","A1"."SSNY","A1".
36 "ZXDID","A1"."KHBH","A2"."WZZBM","A2"."WZZBM","A2"."RKID","A2"."XYSL","A2"."WZZBM" FROM
37 "MP_RKDJ" "A1","MP_RKDJWZ" "A2" WHERE "A1"."RKID"="A2"."RKID" AND "A1"."ZXDID" IS NULL AND
38 TO_NUMBER("A1"."RKZT")=2 AND "A1"."SSNY"<'201311' (accessing 'WN' )
39
40 7 - SELECT "RKID","WZZBM" FROM "MP_RKDJWZ" "A1" WHERE "WZZBM"=:1 (accessing 'WN' )
41
42 8 - SELECT "RKID","RKZT","ZXDID" FROM "MP_RKDJ" "A2" WHERE "ZXDID"=:1 AND
43 TO_NUMBER("RKZT")=3 AND "RKID"=:2 (accessing 'WN' )
44
45 11 - SELECT "RKID","WZZBM","XYSL" FROM "MP_RKDJWZ" "A1" WHERE "WZZBM"=:1 (accessing 'WN'
46 )
47
48 12 - SELECT "RKID","RKZT","ZXDID" FROM "MP_RKDJ" "A2" WHERE "ZXDID"=:1 AND
49 TO_NUMBER("RKZT")=3 AND "RKID"=:2 (accessing 'WN' )
50
51 14 - EXPLAIN PLAN INTO PLAN_TABLE@! FOR SELECT
52 "A2"."KHBH","A2"."KHMC","A3"."WZZBM","A3"."WZMBM","A3"."WZMC","A3"."WZGG","A1"."SL","A3"."J
53 LDW","A3"."WZFLMBM","A1"."SL"*TO_NUMBER("A3"."WZFLMBM") FROM "MP_WZBM" "A3","MP_GYCJDA"
54 "A2", (SELECT "A5"."KHBH" "KHBH","A4"."WZZBM" "WZZBM",SUM(CASE "A5"."RKZT" WHEN '2' THEN
55 "A4"."XYSL" ELSE (-1)*"A4"."XYSL" END ) "SL" FROM "MP_RKDJ" "A5","MP_RKDJWZ" "A4" WHERE
56 "A5"."RKID"="A4"."RKID" AND (TO_NUMBER("A5"."RKZT")=2 OR TO_NUMBER("A5"."RKZT")=3) AND
57 "A5"."SSNY"<'201311' GROUP BY "A5"."KHBH","A4"."WZZBM" HAVING SUM(CASE "A5"."RKZT" WHEN
58 '2' THEN "A4"."XYSL" ELSE (-1)*"A4"."XYSL" END )>0) "A1" WHERE "A2"."KHBH"="A1"."KHBH" AND
59 "A3"."WZZBM"="A1"."WZZBM" (accessing 'WN' )
SELECT gys.khbh,
gys.khmc,
wz.wzzbm,
wz.wzmbm,
wz.wzmc,
wz.wzgg,
a.sl,
wz.jldw,
wz.wzflmbm,
a.sl * wz.wzflmbm jhje,
a.rkids
FROM mp_wzbm@wn wz,
mp_gycjda@wn gys,
(SELECT m.khbh,
d.wzzbm,
SUM(CASE m.rkzt
WHEN '2' THEN
d.xysl
ELSE
-1 * d.xysl
END) sl,
wmsys.wm_concat(CASE
WHEN (m1.zxdid IS NULL OR nvl(m1.xysl, 0) < d.xysl) THEN
m.rkid
END) AS rkids
FROM mp_rkdj@wn m
INNER JOIN mp_rkdjwz@wn d
ON (m.rkid = d.rkid)
LEFT JOIN (SELECT SUM(d1.xysl) AS xysl, m1.zxdid, d1.wzzbm
FROM mp_rkdj@wn m1, mp_rkdjwz@wn d1
WHERE m1.rkid = d1.rkid
AND m1.rkzt = 3
GROUP BY m1.zxdid, d1.wzzbm) m1
ON (m1.zxdid = = m.rkid AND m1.wzzbm = d.wzzbm)
WHERE m.rkzt IN (2, 3)
AND m.ssny < '201311'
GROUP BY m.khbh, d.wzzbm) a
WHERE a.sl > 0
AND gys.khbh = a.khbh
AND wz.wzzbm = a.wzzbm
改后的语句直接走了hash，这也好，省的加hint了。