动态性能视图v$lock访问很慢的解决办法

现象如下：我在OA生产库上执行如下语句，要3分钟左右猜出结果，但是我在其他生产库上执行结果几乎是秒出，会是什么原因？
 我担心的原因，如果哪天出现session阻塞，那我岂不是要完蛋，阻塞session查不出来，kill不掉，到时估计就只能重启应用或者数据库了（PS：之前就出现过一次，不过当时并未将注意力放在这个上面）
 SQL> select sid,lmode,type,request,block from v$lock where type in ('TX','TM') order by 1,3;
        SID      LMODE TY    REQUEST      BLOCK
 ---------- ---------- -- ---------- ----------
          9          6 TX          0          2
        634          6 TX          0          2
       1899          6 TX          0          2
       2847          6 TX          0          2
       3155          6 TX          0          2
       3313          6 TX          0          2
       3461          6 TX          0          2
       5186          6 TX          0          2
       5360          6 TX          0          2
       6764          6 TX          0          2
       8186          3 TM          0          2
        SID      LMODE TY    REQUEST      BLOCK
 ---------- ---------- -- ---------- ----------
       8186          6 TX          0          2
       9107          6 TX          0          2
 13 rows selected.
 这结果出来要3分多钟
 
分析下语句的执行计划
 SQL>  set linesize 150;
 SQL> select sid,lmode,type,request,block from v$lock where type in ('TX','TM') order by 1,3;
 Execution Plan
 ----------------------------------------------------------
 Plan hash value: 3010872788
 --------------------------------------------------------------------------------------
 | Id  | Operation               | Name       | Rows  | Bytes | Cost (%CPU)| Time     |
 --------------------------------------------------------------------------------------
 |   0 | SELECT STATEMENT        |            |     1 |   105 |     2 (100)| 00:00:01 |
 |   1 |  SORT ORDER BY          |            |     1 |   105 |     2 (100)| 00:00:01 |
 |*  2 |   HASH JOIN             |            |     1 |   105 |     1 (100)| 00:00:01 |
 |   3 |    MERGE JOIN CARTESIAN |            |     1 |    54 |     0   (0)| 00:00:01 |
 |*  4 |     FIXED TABLE FULL    | X$KSUSE    |     1 |    32 |     0   (0)| 00:00:01 |
 |   5 |     BUFFER SORT         |            |     1 |    22 |     0   (0)| 00:00:01 |
 |*  6 |      FIXED TABLE FULL   | X$KSQRS    |     1 |    22 |     0   (0)| 00:00:01 |
 |   7 |    VIEW                 | GV$_LOCK   |    10 |   510 |     0   (0)| 00:00:01 |
 |   8 |     UNION-ALL           |            |       |       |            |          |
 |*  9 |      FILTER             |            |       |       |            |          |
 |  10 |       VIEW              | GV$_LOCK1  |     2 |   102 |     0   (0)| 00:00:01 |
 |  11 |        UNION-ALL        |            |       |       |            |          |
 |* 12 |         FIXED TABLE FULL| X$KDNSSF   |     1 |    77 |     0   (0)| 00:00:01 |
 |* 13 |         FIXED TABLE FULL| X$KSQEQ    |     1 |    77 |     0   (0)| 00:00:01 |
 |* 14 |      FIXED TABLE FULL   | X$KTADM    |     1 |    77 |     0   (0)| 00:00:01 |
 |* 15 |      FIXED TABLE FULL   | X$KTATRFIL |     1 |    77 |     0   (0)| 00:00:01 |
 |* 16 |      FIXED TABLE FULL   | X$KTATRFSL |     1 |    77 |     0   (0)| 00:00:01 |
 |* 17 |      FIXED TABLE FULL   | X$KTATL    |     1 |    77 |     0   (0)| 00:00:01 |
 |* 18 |      FIXED TABLE FULL   | X$KTSTUSC  |     1 |    77 |     0   (0)| 00:00:01 |
 |* 19 |      FIXED TABLE FULL   | X$KTSTUSS  |     1 |    77 |     0   (0)| 00:00:01 |
 |* 20 |      FIXED TABLE FULL   | X$KTSTUSG  |     1 |    77 |     0   (0)| 00:00:01 |
 |* 21 |      FIXED TABLE FULL   | X$KTCXB    |     1 |    77 |     0   (0)| 00:00:01 |
 --------------------------------------------------------------------------------------
 Predicate Information (identified by operation id):
 ---------------------------------------------------
    2 - access("SADDR"="S"."ADDR" AND TO_CHAR(USERENV('INSTANCE'))||RAWTOHEX("R
               ADDR")=TO_CHAR("R"."INST_ID")||RAWTOHEX("R"."ADDR"))
    4 - filter("S"."INST_ID"=USERENV('INSTANCE'))
    6 - filter("R"."KSQRSIDT"='TM' OR "R"."KSQRSIDT"='TX')
    9 - filter(USERENV('INSTANCE') IS NOT NULL)
   12 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   13 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   14 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   15 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   16 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   17 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   18 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   19 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   20 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSOBFLG",1)<>0)
   21 - filter(("KSQLKMOD"<>0 OR "KSQLKREQ"<>0) AND
               "INST_ID"=USERENV('INSTANCE') AND BITAND("KSSPAFLG",1)<>0)
 
做level12的10046事件
SQL> alter session set events '10046 trace name context forever, level 12';

Session altered.

SQL> select sid,lmode,type,request,block from v$lock where type in ('TX','TM') order by 1,3;

       SID      LMODE TY    REQUEST      BLOCK
---------- ---------- -- ---------- ----------
       634          6 TX          0          2
      2847          6 TX          0          2
      3461          6 TX          0          2
      3631          6 TM          0          2
      5186          6 TX          0          2
      5829          6 TX          0          2
      6458          6 TX          0          2
      9426          6 TX          0          2

8 rows selected.

SQL> alter session set events '10046 trace name context off';

Session altered.

tkprof出来的trace文件
 TKPROF: Release 11.2.0.3.0 - Development on Fri Mar 1 13:54:30 2013
 
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
 
Trace file: oaprod1_ora_16214.trc
 Sort options: default
 
********************************************************************************
 count    = number of times OCI procedure was executed
 cpu      = cpu time in seconds executing
elapsed  = elapsed time in seconds executing
 disk     = number of physical reads of buffers from disk
 query    = number of buffers gotten for consistent read
 current  = number of buffers gotten in current mode (usually for update)
 rows     = number of rows processed by the fetch or execute call
 ********************************************************************************
 
SQL ID: c4ghdvdm6vbfv Plan Hash: 3010872788
 
select sid,lmode,type,request,block
from
 v$lock where type in ('TX','TM') order by 1,3
 

call     count       cpu    elapsed       disk      query    current        rows
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 Parse        1      0.02       0.02          0          0          0           0
 Execute      1      0.00       0.00          0          0          0           0
 Fetch        2    310.83     402.58     952800          0          8           8
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 total        4    310.86     402.60     952800          0          8           8
 
Misses in library cache during parse: 1
 Optimizer mode: ALL_ROWS
 Parsing user id: SYS
 Number of plan statistics captured: 1
 
Rows (1st) Rows (avg) Rows (max)  Row Source Operation
 ---------- ---------- ----------  ---------------------------------------------------
          8          8          8  SORT ORDER BY (cr=0 pr=952800 pw=952800 time=402582277 us cost=2 size=105 card=1)
          8          8          8   HASH JOIN  (cr=0 pr=952800 pw=952800 time=382540704 us cost=1 size=105 card=1)
 134180992  134180992  134180992    MERGE JOIN CARTESIAN (cr=0 pr=0 pw=0 time=107803810 us cost=0 size=54 card=1)
      10048      10048      10048     FIXED TABLE FULL X$KSUSE (cr=0 pr=0 pw=0 time=145542 us cost=0 size=32 card=1)
 134180992  134180992  134180992     BUFFER SORT (cr=0 pr=0 pw=0 time=51017140 us cost=0 size=22 card=1)
      13354      13354      13354      FIXED TABLE FULL X$KSQRS (cr=0 pr=0 pw=0 time=26869 us cost=0 size=22 card=1)
        480        480        480    VIEW  GV$_LOCK (cr=0 pr=0 pw=0 time=18205 us cost=0 size=510 card=10)
        480        480        480     UNION-ALL  (cr=0 pr=0 pw=0 time=18081 us)
        472        472        472      FILTER  (cr=0 pr=0 pw=0 time=17267 us)
        472        472        472       VIEW  GV$_LOCK1 (cr=0 pr=0 pw=0 time=17139 us cost=0 size=102 card=2)
        472        472        472        UNION-ALL  (cr=0 pr=0 pw=0 time=16784 us)
          0          0          0         FIXED TABLE FULL X$KDNSSF (cr=0 pr=0 pw=0 time=12111 us cost=0 size=77 card=1)
        472        472        472         FIXED TABLE FULL X$KSQEQ (cr=0 pr=0 pw=0 time=4068 us cost=0 size=77 card=1)
          0          0          0      FIXED TABLE FULL X$KTADM (cr=0 pr=0 pw=0 time=108012 us cost=0 size=77 card=1)
          0          0          0      FIXED TABLE FULL X$KTATRFIL (cr=0 pr=0 pw=0 time=29 us cost=0 size=77 card=1)
          0          0          0      FIXED TABLE FULL X$KTATRFSL (cr=0 pr=0 pw=0 time=12 us cost=0 size=77 card=1)
          0          0          0      FIXED TABLE FULL X$KTATL (cr=0 pr=0 pw=0 time=150 us cost=0 size=77 card=1)
          0          0          0      FIXED TABLE FULL X$KTSTUSC (cr=0 pr=0 pw=0 time=452 us cost=0 size=77 card=1)
          0          0          0      FIXED TABLE FULL X$KTSTUSS (cr=0 pr=0 pw=0 time=172 us cost=0 size=77 card=1)
          0          0          0      FIXED TABLE FULL X$KTSTUSG (cr=0 pr=0 pw=0 time=169 us cost=0 size=77 card=1)
          8          8          8      FIXED TABLE FULL X$KTCXB (cr=0 pr=0 pw=0 time=63711 us cost=0 size=77 card=1)
 

Elapsed times include waiting on following events:
   Event waited on                             Times   Max. Wait  Total Waited
   ----------------------------------------   Waited  ----------  ------------
   SQL*Net message to client                       2        0.00          0.00
   asynch descriptor resize                      174        0.00          0.00
   Disk file operations I/O                        1        0.00          0.00
   CSS initialization                              2        0.02          0.02
   CSS operation: action                           2        0.01          0.02
   CSS operation: query                            6        0.00          0.00
   direct path write temp                      30839        0.51         29.56
   direct path read temp                       63516        0.26         64.82
   SQL*Net message from client                     2       80.46         80.46
 ********************************************************************************
 
SQL ID: 06nvwn223659v Plan Hash: 0
 
alter session set events '10046 trace name context off'
 

call     count       cpu    elapsed       disk      query    current        rows
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 Parse        1      0.00       0.00          0          0          0           0
 Execute      1      0.00       0.00          0          0          0           0
 Fetch        0      0.00       0.00          0          0          0           0
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 total        2      0.00       0.00          0          0          0           0
 
Misses in library cache during parse: 0
 Parsing user id: SYS
 

********************************************************************************
 
OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS
 
call     count       cpu    elapsed       disk      query    current        rows
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 Parse        2      0.02       0.02          0          0          0           0
 Execute      2      0.00       0.00          0          0          0           0
 Fetch        2    310.83     402.58     952800          0          8           8
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 total        6    310.86     402.60     952800          0          8           8
 
Misses in library cache during parse: 1
 
Elapsed times include waiting on following events:
   Event waited on                             Times   Max. Wait  Total Waited
   ----------------------------------------   Waited  ----------  ------------
   SQL*Net message to client                       3        0.00          0.00
   SQL*Net message from client                     3       80.46        102.99
   asynch descriptor resize                      174        0.00          0.00
   Disk file operations I/O                        1        0.00          0.00
   CSS initialization                              2        0.02          0.02
   CSS operation: action                           2        0.01          0.02
   CSS operation: query                            6        0.00          0.00
   direct path write temp                      30839        0.51         29.56
   direct path read temp                       63516        0.26         64.82
 

OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS
 
call     count       cpu    elapsed       disk      query    current        rows
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 Parse        0      0.00       0.00          0          0          0           0
 Execute      0      0.00       0.00          0          0          0           0
 Fetch        0      0.00       0.00          0          0          0           0
 ------- ------  -------- ---------- ---------- ---------- ----------  ----------
 total        0      0.00       0.00          0          0          0           0
 
Misses in library cache during parse: 0
 
    2  user  SQL statements in session.
     0  internal SQL statements in session.
     2  SQL statements in session.
 ********************************************************************************
 Trace file: oaprod1_ora_16214.trc
 Trace file compatibility: 11.1.0.7
 Sort options: default
 
       1  session in tracefile.
        2  user  SQL statements in trace file.
        0  internal SQL statements in trace file.
        2  SQL statements in trace file.
        2  unique SQL statements in trace file.
    95414  lines in trace file.
      483  elapsed seconds in trace file.
     
从上面分析来看竟然有大量的读，有些不可思议，找不到原因只好去support.oracle.com发SR寻求帮助    
oracle给了回复如下：
 这个问题是由于oracle没有对fixed object进行stats收集.
请执行以后命令收集fixed object的统计个息, 再测试一下这个问题.
 SQL> exec DBMS_STATS.gather_fixed_objects_stats();
 
或者,

在查询上加个/*+rule*/的hint再测试一下.
 
select /*+rule*/ sid,lmode,type,request,block from v$lock where type in ('TX','TM') order by 1,3;

至此问题已经基本结果，v$lock查询时间正常