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问题描述：
10月25日上午滨州网通的工程师报告OSS应用系统运行缓慢，具体操作是通过OSS系统查询话单，很长时间才能返回结果，严重影响了客户的正常使用。
问题处理：
1.登陆数据库主机，用sar命令看到idle的值持续为0，CPU的资源已经耗尽：
bz_db1# sar 2 4
SunOS kest 5.8 Generic_108528-19 sun4u 10/26/04
10:56:46 %usr %sys %wio %idle
10:56:48 1 4 95 0
10:56:50 1 5 94 0
10:56:52 0 6 93 0
10:56:54 1 6 93 0
Average 1 5 94 0
2.使用TOP命令看到有两个明显占用CPU利用率过高的进程,以下是top命令的结果:
bz_db1# top
last pid: 1664;load averages: 3.26, 3.24, 3.69
159 processes: 152 sleeping, 2 running, 2 zombie, 1 stopped, 2 on cpu
CPU states: 1.5% idle, 72.5% user, 17.9% kernel, 8.0% iowait, 0.0% swap
Memory: 2.0G real, 233M free, 2.0G swap in use, 3.4G swap free
PID USERNAME THR PR NCE SIZE RES STATE TIME FLTS CPU COMMAND
27420 oracle 1 10 0 1.3G 1.2G cpu01 22.9H 2 31.94% oracle
27418 oracle 1 10 0 1.3G 1.2G run 23.0H 6 26.86% oracle
5943 oracle 1 59 0 1.3G 1.2G sleep 25:26 37 4.92% oracle
6295 oracle 1 55 0 1.3G 1.2G run 25:14 74 4.90% oracle
7778 oracle 1 43 0 1.3G 1.2G sleep 11:43 110 4.86% oracle
13270 oracle 1 59 0 1.3G 1.2G sleep 210.6H 0 0.96% oracle
13056 oracle 1 48 0 1.3G 1.2G sleep 303:30 0 0.37% oracle
10653 root 1 58 0 2560K 1624K cpu00 0:00 0 0.32% top
18827 oracle 1 58 0 1.3G 1.2G sleep 18.4H 0 0.31% oracle
12748 oracle 258 58 0 1.3G 1.2G sleep 555:14 0 0.21% oracle
10634 oracle 1 59 0 1.3G 1.2G sleep 0:01 0 0.21% oracle
28458 oracle 1 58 0 1.3G 1.2G sleep 535:02 0 0.18% oracle
13075 oracle 1 59 0 1.3G 1.2G sleep 326:33 0 0.15% oracle
13173 oracle 1 58 0 1.3G 1.2G sleep 593:07 0 0.13% oracle
4927 oracle 1 59 0 1.3G 1.2G sleep 33.4H 0 0.11% oracle
可以看到这两个进程号分别是27420和27418.
3.捕获占用CPU利用率过高的SQL语句：
以下用到了我总结的SQL语句：
SQL>set line 240
SQL>set verify off
SQL>column sid format 999
SQL>column pid format 999
SQL>column S_# format 999
SQL>column username format A9 heading "ORA User"
SQL>column program format a29
SQL>column SQL format a60
SQL>COLUMN OSname format a9 Heading "OS User"
SQL>SELECT P.pid pid,S.sid sid,P.spid spid,S.username username,
S.osuser osname,P.serial# S_#,P.terminal,P.program program,
P.background,S.status,RTRIM(SUBSTR(a.sql_text, 1, 80)) SQL
FROM v$process P, v$session S,v$sqlarea A WHERE P.addr = s.paddr
AND S.sql_address = a.address (+) AND P.spid LIKE ''''%&1%'''';
Enter value for 1: 27420（注意这里应输入占用CPU最高的进程对应的PID）
得到以下SQL语句：
Select nvl(sum(LOCALCHARGE),0),nvl(sum(usage),0) from LOCALUSAGE where to_char(ENDTIME,''''YYYYMMDD'''')=20041016
and LOCALCHARGE>0 and caller like ''''0543886%'''';
27418进程对应的SQL语句如下：
select nvl(sum(LOCALCHARGE),0) from LOCALUSAGE where to_char(ENDTIME,''''YYYYMMDD'''')=20041016 and caller like ''''0543888%'''';
4.使用相关用户连接到数据库，检查其执行计划:
SQL>connect wacos/oss
Connected.
SQL>@?/rdbms/admin/utlxplan.sql
Table created.
SQL>set autotrace on
SQL>set timing on
SQL>Select nvl(sum(LOCALCHARGE),0),nvl(sum(usage),0) from LOCALUSAGE where to_char(ENDTIME,''''YYYYMMDD'''')=20041016
and LOCALCHARGE>0 and caller like ''''0543886%'''';
NVL(SUM(LOCALCHARGE),0) NVL(SUM(USAGE),0)
----------------------- -----------------
0 0
Elapsed: 00:02:56.37
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=13435 Card=1 Bytes=5
3)
1 0 SORT (AGGREGATE)
2 1 PARTITION RANGE (ALL)
3 2 TABLE ACCESS (FULL) OF ''''LOCALUSAGE'''' (Cost=13435 Card=1
81 Bytes=9593)
Statistics
----------------------------------------------------------
258 recursive calls
0 db block gets
88739 consistent gets
15705 physical reads
0 redo size
580 bytes sent via SQL*Net to client
651 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
8 sorts (memory)
0 sorts (disk)
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