性能改进的新手，我正在努力解决以下问题。下表用于跟踪登记者的状态。每次状态更改时，都会为登记者插入新行。我试图获得给定登记者的最佳状态，以获得需要亚秒响应时间的Web界面。我已经更改了自联接以使用rank（）和更新的索引，这确实有帮助，但是当我尝试添加where条件以查找给定的enrollment_process_status时，查询将花费一秒钟来响应。关于如何改进这个的任何建议？
CREATE TABLE "TM"."ENRL_PROCESS_STATUS"
( "ENRL_ENROLLEE_RECORD_SK" NUMBER(*,0) NOT NULL ENABLE,
"ENRL_PROCESS_STATUS_SK" NUMBER(*,0) NOT NULL ENABLE,
"ENROLLMENT_PROCESS_STATUS" NUMBER(*,0),
"BACKOUT_ID" NUMBER(*,0),
"CREATE_DTTM" TIMESTAMP (6),
"CREATE_LOGIN" VARCHAR2(50 BYTE),
"UPDATE_DTTM" TIMESTAMP (6),
"UPDATE_LOGIN" VARCHAR2(50 BYTE),
"PROCESS_STATUS_REASON_CD" NUMBER(*,0),
CONSTRAINT "ENRL_PROCESS_STATUS_PK" PRIMARY KEY ("ENRL_PROCESS_STATUS_SK")
USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
TABLESPACE "USERS" ENABLE,
CONSTRAINT "ENRL_PROCESS_STATUS_FK1" FOREIGN KEY ("ENRL_ENROLLEE_RECORD_SK")
REFERENCES "TM"."ENRL_ENROLLEE_RECORD" ("ENRL_ENROLLEE_RECORD_SK") ENABLE
) SEGMENT CREATION IMMEDIATE
PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255
NOCOMPRESS LOGGING
STORAGE(INITIAL 81920 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
TABLESPACE "USERS" ;
CREATE INDEX "TM"."TOM1" ON "TM"."ENRL_PROCESS_STATUS" ("ENRL_ENROLLEE_RECORD_SK", "CREATE_DTTM" DESC, "ENROLLMENT_PROCESS_STATUS", "PROCESS_STATUS_REASON_CD")
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
TABLESPACE "USERS" ;
SQL以识别登记者的最新状态
SELECT enrl_enrollee_record_sk, enrollment_process_status, PROCESS_STATUS_REASON_CD
FROM
(
SELECT
enrl_enrollee_record_sk, enrollment_process_status, PROCESS_STATUS_REASON_CD,
rank() over (partition by enrl_enrollee_record_sk ORDER BY CREATE_DTTM DESC) as seqnum
FROM TM.enrl_process_status ps
) A
WHERE seqnum = 1
AND (ENROLLMENT_PROCESS_STATUS IN (3,4,5,8) OR (ENROLLMENT_PROCESS_STATUS = 10 AND PROCESS_STATUS_REASON_CD in (1,3)))
如果没有（AND）条件，查询将在0秒内运行，并带有以下解释计划。
Plan hash value: 2893856400
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 3420K| 169M| 7592 (1)| 00:01:47 |
|* 1 | VIEW | | 3420K| 169M| 7592 (1)| 00:01:47 |
|* 2 | WINDOW NOSORT | | 3420K| 71M| 7592 (1)| 00:01:47 |
| 3 | INDEX FULL SCAN| TOM1 | 3420K| 71M| 7592 (1)| 00:01:47 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("SEQNUM"=1)
2 - filter(RANK() OVER ( PARTITION BY "ENRL_ENROLLEE_RECORD_SK"
ORDER BY SYS_OP_DESCEND("CREATE_DTTM"))<=1)
使用（AND）条件，查询运行时间超过1.2秒，并带有以下解释计划。关于如何提高绩效的任何想法？
Plan hash value: 2893856400
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 3420K| 169M| 7592 (1)| 00:01:47 |
|* 1 | VIEW | | 3420K| 169M| 7592 (1)| 00:01:47 |
|* 2 | WINDOW NOSORT | | 3420K| 71M| 7592 (1)| 00:01:47 |
| 3 | INDEX FULL SCAN| TOM1 | 3420K| 71M| 7592 (1)| 00:01:47 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("SEQNUM"=1 AND (("ENROLLMENT_PROCESS_STATUS"=3 OR
"ENROLLMENT_PROCESS_STATUS"=4 OR "ENROLLMENT_PROCESS_STATUS"=5 OR
"ENROLLMENT_PROCESS_STATUS"=8) OR "ENROLLMENT_PROCESS_STATUS"=10 AND
("PROCESS_STATUS_REASON_CD"=1 OR "PROCESS_STATUS_REASON_CD"=3)))
2 - filter(RANK() OVER ( PARTITION BY "ENRL_ENROLLEE_RECORD_SK"
ORDER BY SYS_OP_DESCEND("CREATE_DTTM"))<=1)