ORACLE:INDEX FULL SCAN--99%是最烂的执行计划
原sql：
SELECT *
FROM ( SELECT c.id,
c.username,
c.keyword,
c.batchid,
i.bc_id,
c.title,
i.checked,
c.srcimg,
i.targ etimg,
c.providerid,
c.pricerange,
c.bc_param,
c.service
FROM aladdin_imgcutcheck c,
aladdin_imgcomp i,
vr_keyword_baidu_aladdin b
WHERE c.bc_id = i.bc_id
AND c.srcimg = i.srcimg
AND c.keyword = b.keyword
AND c.batchid = b.batchid
AND c.state = '0'
AND b.state = 0
AND i.checked = '0'
ORDER BY b.keyword DESC)
WHERE ROWNUM <= :1
Plan hash value: 1095357246
-------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | 6289 (100)| |
|* 1 | COUNT STOPKEY | | | | | |
| 2 | VIEW | | 10 | 28580 | 6289 (1)| 00:01:16 |
| 3 | NESTED LOOPS | | 10 | 6950 | 6289 (1)| 00:01:16 |
| 4 | NESTED LOOPS | | 1302 | 726K| 3763 (1)| 00:00:46 |
|* 5 | TABLE ACCESS BY INDEX ROWID| VR_KEYWORD_BAIDU_ALADDIN | 69228 | 1284K| 239 (0)| 00:00:03 |
| 6 | INDEX FULL SCAN DESCENDING| IND_KEYWORD | 352 | | 3 (0)| 00:00:01 |
|* 7 | TABLE ACCESS BY INDEX ROWID| ALADDIN_IMGCUTCHECK | 7 | 3864 | 20 (0)| 00:00:01 |
|* 8 | INDEX RANGE SCAN | I_ALADDIN_IMGCUTCHECK_KEY | 25 | | 2 (0)| 00:00:01 |
|* 9 | TABLE ACCESS BY INDEX ROWID | ALADDIN_IMGCOMP | 1 | 124 | 2 (0)| 00:00:01 |
|* 10 | INDEX UNIQUE SCAN | I_ALADDIN_IMGCOMP | 1 | | 1 (0)| 00:00:01 |
-------------------------------------------------------------------------------------------------------------
Peeked Binds (identified by position):
--------------------------------------
1 - :1 (NUMBER): 10
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(ROWNUM<=:1)
5 - filter(TO_NUMBER("B"."STATE")=0)
7 - filter(("C"."STATE"='0' AND "C"."BATCHID"="B"."BATCHID"))
8 - access("C"."KEYWORD"="B"."KEYWORD")
9 - filter("I"."CHECKED"='0')
10 - access("C"."BC_ID"="I"."BC_ID" AND "C"."SRCIMG"="I"."SRCIMG")|* 5 | TABLE ACCESS BY INDEX ROWID| VR_KEYWORD_BAIDU_ALADDIN | 69228 | 1284K| 239 (0)| 00:00:03 |
| 6 | INDEX FULL SCAN DESCENDING| IND_KEYWORD | 352 | | 3 (0)| 00:00:01 |
最烂的执行计划，索引全扫描外加回表，由于受ORDER BY b.keyword DESC影响，oracle错误的选择了index扫描 原来5分钟执行不完，修改如下
（新建了一个索引--I_ALADDIN_IMGCOMP_CBST--）
SQL> explain plan for SELECT *
2 FROM ( SELECT /*+ no_index(b IND_KEYWORD) */ c.id,
3 c.username,
4 c.keyword,
5 c.batchid,
6 i.bc_id,
7 c.title,
8 i.checked,
9 c.srcimg,
10 i.targetimg,
11 c.providerid,
12 c.pricerange,
13 c.bc_param,
14 c.service
15 FROM match_manual.aladdin_imgcutcheck c,
16 match_manual.aladdin_imgcomp i,
17 match_manual.vr_keyword_baidu_aladdin b
18 WHERE c.bc_id = i.bc_id
19 AND c.srcimg = i.srcimg
20 AND c.keyword = b.keyword
21 AND c.batchid = b.batchid
22 AND c.state = '0'
23 AND b.state = 0
24 AND i.checked = '0'
25 ORDER BY b.keyword DESC)
26 WHERE ROWNUM <= 10;
Explained.
SQL> set lines 300
SQL> set pagesize 0
SQL> /
Plan hash value: 3545217694
--------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time |
--------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 10 | 28580 | | 45543 (1)| 00:09:07 |
|* 1 | COUNT STOPKEY | | | | | | |
| 2 | VIEW | | 3941 | 10M| | 45543 (1)| 00:09:07 |
|* 3 | SORT ORDER BY STOPKEY | | 3941 | 2674K| 5752K| 45543 (1)| 00:09:07 |
|* 4 | HASH JOIN | | 3941 | 2674K| 2096K| 44963 (1)| 00:09:00 |
|* 5 | TABLE ACCESS FULL | VR_KEYWORD_BAIDU_ALADDIN | 69228 | 1284K| | 1012 (2)| 00:00:13 |
|* 6 | TABLE ACCESS BY INDEX ROWID| ALADDIN_IMGCUTCHECK | 1 | 552 | | 5 (0)| 00:00:01 |
| 7 | NESTED LOOPS | | 7799 | 5148K| | 43592 (1)| 00:08:44 |
|* 8 | INDEX RANGE SCAN | I_ALADDIN_IMGCOMP_CBST | 10813 | 1309K| | 207 (0)| 00:00:03 |
|* 9 | INDEX RANGE SCAN | INX_BC_ID | 2 | | | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(ROWNUM<=10)
3 - filter(ROWNUM<=10)
4 - access("C"."KEYWORD"="B"."KEYWORD" AND "C"."BATCHID"="B"."BATCHID")
5 - filter(TO_NUMBER("B"."STATE")=0)
6 - filter("C"."STATE"='0' AND "C"."SRCIMG"="I"."SRCIMG")
8 - access("I"."CHECKED"='0')
9 - access("C"."BC_ID"="I"."BC_ID")
现在 2秒执行完成