Oracle诊断案例----如何捕获问题SQL解决过度CPU消耗问题
--使用vmstat,top等辅助解决Oracle数据库性能问题
Last Updated: Sunday, 2004-10-24 0:37 Eygle
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问题描述:
开发人员报告系统运行缓慢，影响用户访问.
1.登陆数据库主机
使用vmstat检查，发现CPU资源已经耗尽，大量任务位于运行队列:
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>
>
>
> bash-2.03$ vmstat 3
> procs memory page disk faults cpu
> r b w swap free re mf pi po fr de sr s6 s9 s1 sd in sy cs us sy id
> 0 0 0 5504232 1464112 0 0 0 0 0 0 0 0 1 1 0 4294967196 0 0 -84 -5 -145
> 131 0 0 5368072 1518360 56 691 0 2 2 0 0 0 1 0 0 3011 7918 2795 97 3 0
> 131 0 0 5377328 1522464 81 719 0 2 2 0 0 0 1 0 0 2766 8019 2577 96 4 0
> 130 0 0 5382400 1524776 67 682 0 0 0 0 0 0 0 0 0 3570 8534 3316 97 3 0
> 134 0 0 5373616 1520512 127 1078 0 2 2 0 0 0 1 0 0 3838 9584 3623 96 4 0
> 136 0 0 5369392 1518496 107 924 0 5 5 0 0 0 0 0 0 2920 8573 2639 97 3 0
> 132 0 0 5364912 1516224 63 578 0 0 0 0 0 0 0 0 0 3358 7944 3119 97 3 0
> 129 0 0 5358648 1511712 189 1236 0 0 0 0 0 0 0 0 0 3366 10365 3135 95 5 0
> 129 0 0 5354528 1511304 120 1194 0 0 0 0 0 0 0 4 0 3235 8864 2911 96 4 0
> 128 0 0 5346848 1507704 99 823 0 0 0 0 0 0 0 3 0 3189 9048 3074 96 4 0
> 125 0 0 5341248 1504704 80 843 0 2 2 0 0 0 6 1 0 3563 9514 3314 95 5 0
> 133 0 0 5332744 1501112 79 798 0 0 0 0 0 0 0 1 0 3218 8805 2902 97 3 0
> 129 0 0 5325384 1497368 107 643 0 2 2 0 0 0 1 4 0 3184 8297 2879 96 4 0
> 126 0 0 5363144 1514320 81 753 0 0 0 0 0 0 0 0 0 2533 7409 2164 97 3 0
> 136 0 0 5355624 1510512 169 566 786 0 0 0 0 0 0 1 0 3002 8600 2810 96 4 0
> 130 1 0 5351448 1502936 267 580 1821 0 0 0 0 0 0 0 0 3126 7812 2900 96 4 0
> 129 0 0 5347256 1499568 155 913 2 2 2 0 0 0 0 1 0 2225 8076 1941 98 2 0
> 116 0 0 5338192 1495400 177 1162 0 0 0 0 0 0 0 1 0 1947 7781 1639 97 3 0
>
2.使用Top命令
观察进程CPU耗用,发现没有明显过高CPU使用的进程
$ top
>
> last pid: 28313; load averages: 99.90, 117.54, 125.71 23:28:38
> 296 processes: 186 sleeping, 99 running, 2 zombie, 9 on cpu
> CPU states: 0.0% idle, 96.5% user, 3.5% kernel, 0.0% iowait, 0.0% swap
> Memory: 4096M real, 1404M free, 2185M swap in use, 5114M swap free
>
> PID USERNAME THR PRI NICE SIZE RES STATE TIME CPU COMMAND
> 27082 oracle8i 1 33 0 1328M 1309M run 0:17 1.29% oracle
> 26719 oracle8i 1 55 0 1327M 1306M sleep 0:29 1.11% oracle
> 28103 oracle8i 1 35 0 1327M 1304M run 0:06 1.10% oracle
> 28161 oracle8i 1 25 0 1327M 1305M run 0:04 1.10% oracle
> 26199 oracle8i 1 45 0 1328M 1309M run 0:42 1.10% oracle
> 26892 oracle8i 1 33 0 1328M 1310M run 0:24 1.09% oracle
> 27805 oracle8i 1 45 0 1327M 1306M cpu/1 0:10 1.04% oracle
> 23800 oracle8i 1 23 0 1327M 1306M run 1:28 1.03% oracle
> 25197 oracle8i 1 34 0 1328M 1309M run 0:57 1.03% oracle
> 21593 oracle8i 1 33 0 1327M 1306M run 2:12 1.01% oracle
> 27616 oracle8i 1 45 0 1329M 1311M run 0:14 1.01% oracle
> 27821 oracle8i 1 43 0 1327M 1306M run 0:10 1.00% oracle
> 26517 oracle8i 1 33 0 1328M 1309M run 0:33 0.97% oracle
> 25785 oracle8i 1 44 0 1328M 1309M run 0:46 0.96% oracle
> 26241 oracle8i 1 45 0 1327M 1306M run 0:42 0.96% oracle
>
>
3.检查进程数量
> > bash-2.03$ ps -ef|grep ora|wc -l > 258 > bash-2.03$ ps -ef|grep ora|wc -l > 275 > bash-2.03$ ps -ef|grep ora|wc -l > 274 > bash-2.03$ ps -ef|grep ora|wc -l > 278 > bash-2.03$ ps -ef|grep ora|wc -l > 277 > bash-2.03$ ps -ef|grep ora|wc -l > 366 >
发现系统存在大量Oracle进程,大约在300左右，而正常情况下Oracle连接数应该在100左右.
4.检查数据库
查询v$session_wait获取各进程等待事件
>
>
> SQL> select sid,event,p1,p1text from v$session_wait;
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 124 latch free 1.6144E+10 address
> 1 pmon timer 300 duration
> 2 rdbms ipc message 300 timeout
> 3 rdbms ipc message 300 timeout
> 11 rdbms ipc message 30000 timeout
> 6 rdbms ipc message 180000 timeout
> 4 rdbms ipc message 300 timeout
> 134 rdbms ipc message 6000 timeout
> 147 rdbms ipc message 6000 timeout
> 275 rdbms ipc message 17995 timeout
> 274 rdbms ipc message 6000 timeout
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 118 rdbms ipc message 6000 timeout
> 7 buffer busy waits 17 file#
> 56 buffer busy waits 17 file#
> 161 buffer busy waits 17 file#
> 195 buffer busy waits 17 file#
> 311 buffer busy waits 17 file#
> 314 buffer busy waits 17 file#
> 205 buffer busy waits 17 file#
> 269 buffer busy waits 17 file#
> 200 buffer busy waits 17 file#
> 164 buffer busy waits 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 140 buffer busy waits 17 file#
> 66 buffer busy waits 17 file#
> 10 db file sequential read 17 file#
> 18 db file sequential read 17 file#
> 54 db file sequential read 17 file#
> 49 db file sequential read 17 file#
> 48 db file sequential read 17 file#
> 46 db file sequential read 17 file#
> 45 db file sequential read 17 file#
> 35 db file sequential read 17 file#
> 30 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 29 db file sequential read 17 file#
> 22 db file sequential read 17 file#
> 178 db file sequential read 17 file#
> 175 db file sequential read 17 file#
> 171 db file sequential read 17 file#
> 123 db file sequential read 17 file#
> 121 db file sequential read 17 file#
> 120 db file sequential read 17 file#
> 117 db file sequential read 17 file#
> 114 db file sequential read 17 file#
> 113 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 111 db file sequential read 17 file#
> 107 db file sequential read 17 file#
> 80 db file sequential read 17 file#
> 222 db file sequential read 17 file#
> 218 db file sequential read 17 file#
> 216 db file sequential read 17 file#
> 213 db file sequential read 17 file#
> 199 db file sequential read 17 file#
> 198 db file sequential read 17 file#
> 194 db file sequential read 17 file#
> 192 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 188 db file sequential read 17 file#
> 249 db file sequential read 17 file#
> 242 db file sequential read 17 file#
> 239 db file sequential read 17 file#
> 236 db file sequential read 17 file#
> 235 db file sequential read 17 file#
> 234 db file sequential read 17 file#
> 233 db file sequential read 17 file#
> 230 db file sequential read 17 file#
> 227 db file sequential read 17 file#
> 336 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 333 db file sequential read 17 file#
> 331 db file sequential read 17 file#
> 329 db file sequential read 17 file#
> 327 db file sequential read 17 file#
> 325 db file sequential read 17 file#
> 324 db file sequential read 17 file#
> 320 db file sequential read 17 file#
> 318 db file sequential read 17 file#
> 317 db file sequential read 17 file#
> 316 db file sequential read 17 file#
> 313 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 305 db file sequential read 17 file#
> 303 db file sequential read 17 file#
> 301 db file sequential read 17 file#
> 293 db file sequential read 17 file#
> 290 db file sequential read 17 file#
> 288 db file sequential read 17 file#
> 287 db file sequential read 17 file#
> 273 db file sequential read 17 file#
> 271 db file sequential read 17 file#
> 257 db file sequential read 17 file#
> 256 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 254 db file sequential read 17 file#
> 252 db file sequential read 17 file#
> 159 db file sequential read 17 file#
> 153 db file sequential read 17 file#
> 146 db file sequential read 17 file#
> 142 db file sequential read 17 file#
> 135 db file sequential read 17 file#
> 133 db file sequential read 17 file#
> 132 db file sequential read 17 file#
> 126 db file sequential read 17 file#
> 79 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 77 db file sequential read 17 file#
> 72 db file sequential read 17 file#
> 70 db file sequential read 17 file#
> 69 db file sequential read 17 file#
> 67 db file sequential read 17 file#
> 63 db file sequential read 17 file#
> 55 db file sequential read 17 file#
> 102 db file sequential read 17 file#
> 96 db file sequential read 17 file#
> 95 db file sequential read 17 file#
> 91 db file sequential read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 81 db file sequential read 17 file#
> 15 db file sequential read 17 file#
> 19 db file scattered read 17 file#
> 50 db file scattered read 17 file#
> 285 db file scattered read 17 file#
> 279 db file scattered read 17 file#
> 255 db file scattered read 17 file#
> 243 db file scattered read 17 file#
> 196 db file scattered read 17 file#
> 187 db file scattered read 17 file#
> 170 db file scattered read 17 file#
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 162 db file scattered read 17 file#
> 138 db file scattered read 17 file#
> 110 db file scattered read 17 file#
> 108 db file scattered read 17 file#
> 92 db file scattered read 17 file#
> 330 db file scattered read 17 file#
> 310 db file scattered read 17 file#
> 302 db file scattered read 17 file#
> 299 db file scattered read 17 file#
> 89 db file scattered read 17 file#
> 5 smon timer 300 sleep time
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 20 SQLNet message to client 1952673792 driver id
> 103 SQLNet message to client 1650815232 driver id
> ....
> 148 SQLNet more data from client 1952673792 driver id
> 291 SQLNet more data from client 1952673792 driver id
>
> 244 rows selected.
发现存在大量db file scattered read及db file sequential read等待.
5.捕获相关SQL
这里用到了我的以下脚本getsqlbysid.sql:
> > SELECT sql_text > FROM v$sqltext a > WHERE a.hash_value = (SELECT sql_hash_value > FROM v$session b > WHERE b.SID = '&sid') > ORDER BY piece ASC > /
>
>
> SQL> @getsql
> Enter value for sid: 18
> old 5: where b.sid='&sid'
> new 5: where b.sid='18'
>
> SQL_TEXT
> ----------------------------------------------------------------
> select i.vc2title,i.numinfoguid from hs_info i where i.intenab
> ledflag = 1 and i.intpublishstate = 1 and i.datpublishdate <=
> sysdate and i.numcatalogguid = 2047 order by i.datpublishdate d
> esc, i.numorder desc
>
> SQL> /
> Enter value for sid: 54
> old 5: where b.sid='&sid'
> new 5: where b.sid='54'
>
> SQL_TEXT
> ----------------------------------------------------------------
> select i.vc2title,i.numinfoguid from hs_info i where i.intenab
> ledflag = 1 and i.intpublishstate = 1 and i.datpublishdate <=
> sysdate and i.numcatalogguid = 33 order by i.datpublishdate des
> c, i.numorder desc
>
> SQL> /
> Enter value for sid: 49
> old 5: where b.sid='&sid'
> new 5: where b.sid='49'
>
> SQL_TEXT
> ----------------------------------------------------------------
> select i.vc2title,i.numinfoguid from hs_info i where i.intenab
> ledflag = 1 and i.intpublishstate = 1 and i.datpublishdate <=
> sysdate and i.numcatalogguid = 26 order by i.datpublishdate des
> c, i.numorder desc
>
对几个全表扫描进程跟踪以后，得到以上SQL语句.
以上语句如果良好编码应该使用绑定变量.但是现在这个不是我们关心的.
使用该应用用户连接，检查其执行计划:
>
> SQL> set autotrace trace explain
> SQL> select i.vc2title,i.numinfoguid
> 2 from hs_info i where i.intenabledflag = 1
> 3 and i.intpublishstate = 1 and i.datpublishdate <=sysdate
> 4 and i.numcatalogguid = 3475
> 5 order by i.datpublishdate desc, i.numorder desc ;
>
> Execution Plan
> ----------------------------------------------------------
> 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=228 Card=1 Bytes=106)
> 1 0 SORT (ORDER BY) (Cost=228 Card=1 Bytes=106)
> 2 1 TABLE ACCESS (FULL) OF 'HS_INFO' (Cost=218 Card=1 Bytes=106)
>
> SQL> select count() from hs_info;
>
> COUNT()
> ----------
> 227404
>
该表这里有22万记录，全表扫描已经不再适合.
检查该表，存在以下索引:
>
> SQL> select index_name,index_type from user_indexes where table_name='HS_INFO';
>
> INDEX_NAME INDEX_TYPE
> ------------------------------ ---------------------------
> HSIDX_INFO1 FUNCTION-BASED NORMAL
> HSIDX_INFO_SEARCHKEY DOMAIN
> PK_HS_INFO NORMAL
>
> 检查索引键值:
>
> SQL> select index_name,column_name from user_ind_columns where table_name ='HS_INFO';
>
> INDEX_NAME COLUMN_NAME
> ------------------------------ --------------------
> HSIDX_INFO1 NUMORDER
> HSIDX_INFO1 SYS_NC00024$
> HSIDX_INFO_SEARCHKEY VC2INDEXWORDS
> PK_HS_INFO NUMINFOGUID
>
> SQL> desc hs_info
> Name Null? Type
> ----------------------------------------------------------------- -------- ---------------------------
> NUMINFOGUID NOT NULL NUMBER(15)
> NUMCATALOGGUID NOT NULL NUMBER(15)
> INTTEXTTYPE NOT NULL NUMBER(38)
> VC2TITLE NOT NULL VARCHAR2(60)
> VC2AUTHOR VARCHAR2(100)
> NUMPREVINFOGUID NUMBER(15)
> NUMNEXTINFOGUID NUMBER(15)
> NUMORDER NOT NULL NUMBER(15)
> DATPUBLISHDATE NOT NULL DATE
> INTPUBLISHSTATE NOT NULL NUMBER(38)
> VC2PUBLISHERID VARCHAR2(30)
> VC2INDEXWORDS VARCHAR2(200)
> VC2WAPPREVPATH VARCHAR2(200)
> VC2WEBPREVPATH VARCHAR2(200)
> VC2WAP2PREVPATH VARCHAR2(200)
> NUMVISITED NOT NULL NUMBER(15)
> INTENABLEDFLAG NOT NULL NUMBER(38)
> DATCREATETIME NOT NULL DATE
> DATMODIFYTIME NOT NULL DATE
> VC2NOTES VARCHAR2(1000)
> INTINFOTYPE NOT NULL NUMBER(38)
> VC2PRIZEFLAG VARCHAR2(1)
> VC2DESC VARCHAR2(1000)
6.决定创建新的索引以消除全表扫描
>
>
> SQL> create index hs_info_NUMCATALOGGUID on hs_info(NUMCATALOGGUID);
>
> Index created.
>
> SQL> set autotrace trace explain
> SQL> select i.vc2title,i.numinfoguid
> 2 from hs_info i where i.intenabledflag = 1
> 3 and i.intpublishstate = 1 and i.datpublishdate <=sysdate
> 4 and i.numcatalogguid = 3475
> 5 order by i.datpublishdate desc, i.numorder desc ;
>
> Execution Plan
> ----------------------------------------------------------
> 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=12 Card=1 Bytes=106)
> 1 0 SORT (ORDER BY) (Cost=12 Card=1 Bytes=106)
> 2 1 TABLE ACCESS (BY INDEX ROWID) OF 'HS_INFO' (Cost=2 Card=1 Bytes=106)
> 3 2 INDEX (RANGE SCAN) OF 'HS_INFO_NUMCATALOGGUID' (NON-UNIQUE) (Cost=1 Card=1)
>
>
7.观察系统状况
原大量等待消失
>
>
> SQL> select sid,event,p1,p1text from v$session_wait where event not like 'SQL%';
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 1 pmon timer 300 duration
> 2 rdbms ipc message 300 timeout
> 3 rdbms ipc message 300 timeout
> 6 rdbms ipc message 180000 timeout
> 59 rdbms ipc message 6000 timeout
> 118 rdbms ipc message 6000 timeout
> 275 rdbms ipc message 30000 timeout
> 147 rdbms ipc message 6000 timeout
> 62 rdbms ipc message 6000 timeout
> 11 rdbms ipc message 30000 timeout
> 4 rdbms ipc message 300 timeout
>
> SID EVENT P1 P1TEXT
> ---------- ------------------------------ ---------- ----------------------------------------------------------------
> 305 db file sequential read 17 file#
> 356 db file sequential read 17 file#
> 19 db file scattered read 17 file#
> 5 smon timer 300 sleep time
>
> 15 rows selected.
>
持续观察的CPU使用情况
> > > bash-2.03$ vmstat 3 > procs memory page disk faults cpu > r b w swap free re mf pi po fr de sr s6 s9 s1 sd in sy cs us sy id > 20 0 0 5421792 1503488 38 434 136 0 0 0 0 0 0 2 0 2931 7795 2622 91 9 0 > 23 1 0 5416080 1500632 95 734 56 0 0 0 0 0 0 0 0 2949 8057 2598 89 11 0 > 26 0 0 5412016 1498480 210 1170 21 5 5 0 0 0 2 1 0 3301 9647 3116 90 10 0 > 25 0 0 5394912 1490160 242 1606 56 0 0 0 0 0 0 1 0 3133 9318 2850 89 11 0 > 40 0 0 5390200 1488112 162 1393 66 0 0 0 0 0 0 0 0 2848 9080 2502 90 10 0 > 40 0 0 5377120 1481792 136 1180 120 2 2 0 0 0 1 1 0 2846 9099 2593 92 8 0 > 36 0 0 5363216 1475168 134 1169 53 0 0 0 0 0 3 2 0 2871 7989 2621 88 12 0 > 39 0 0 5348936 1469160 157 1448 210 0 0 0 0 0 0 0 0 3660 10062 3480 88 12 0 > 35 0 0 5344552 1466472 7 15 56 0 0 0 0 0 0 0 0 2885 7663 2635 92 8 0 > 34 0 0 5343016 1465416 44 386 77 0 0 0 0 0 0 0 0 3197 8486 2902 92 8 0 > 31 0 0 5331568 1459696 178 1491 122 0 0 0 0 0 0 3 0 3237 9461 3005 89 11 0 > 31 0 0 5317792 1453008 76 719 80 0 0 0 0 0 0 0 0 3292 8736 3025 93 7 0 > 31 2 0 5311144 1449552 235 1263 69 2 2 0 0 0 1 0 0 3473 9535 3357 88 12 0 > 25 0 0 5300240 1443920 108 757 18 2 2 0 0 0 1 1 0 2377 7876 2274 95 5 0 > 19 0 0 5295904 1441840 50 377 0 0 0 0 0 0 0 1 0 1915 6598 1599 98 1 0 > ----以上为创建索引之前部分 > ----以下为创建索引之后部分，CPU使用率恢复正常 > procs memory page disk faults cpu > r b w swap free re mf pi po fr de sr s6 s9 s1 sd in sy cs us sy id > 40 1 0 5290040 1439208 315 3894 8 2 2 0 0 0 1 6 0 3631 13414 5206 61 9 30 > 0 1 0 5237192 1414744 731 6749 45 0 0 0 0 0 2 7 0 3264 13558 4941 52 14 34 > 0 0 0 5163632 1380608 747 6585 10 0 0 0 0 0 0 1 0 2617 12291 3901 46 12 41 > 1 0 0 5090224 1348152 712 6079 29 0 0 0 0 0 0 6 0 2825 12416 4178 50 12 39 > 1 0 0 5023672 1317296 714 6183 24 0 0 0 0 0 0 5 0 3166 12424 4745 47 13 40 > 0 0 0 4955872 1287136 737 6258 16 0 0 0 0 0 0 3 0 2890 11777 4432 44 12 44 > 1 0 0 4887888 1256464 809 6234 8 2 2 0 0 0 0 2 0 2809 12066 4247 45 12 43 > 0 0 0 4828912 1228200 312 2364 13 5 5 0 0 0 2 1 0 2410 6816 3492 38 6 57 > 0 0 0 4856816 1240168 8 138 0 0 0 0 0 0 1 0 0 2314 4026 3232 34 4 62 > 0 0 0 4874176 1247712 0 86 0 0 0 0 0 0 0 0 0 2298 3930 3324 35 2 63 > 2 0 0 4926088 1270824 34 560 0 0 0 0 0 0 0 0 0 2192 4694 2612 29 16 55 > 0 0 0 5427320 1512952 53 694 0 0 0 0 0 0 3 2 0 2443 5085 3340 33 12 55 > 0 0 0 5509120 1553136 0 37 0 0 0 0 0 0 0 0 0 2309 3908 3321 35 1 64 > 0 0 0 5562048 1577000 16 234 0 0 0 0 0 0 0 0 0 2507 5187 3433 35 8 57 > 0 0 0 5665672 1623848 252 1896 8 2 2 0 0 0 1 0 0 2091 6548 2939 34 5 61 > 0 0 0 5654752 1618208 5 173 16 0 0 0 0 0 0 0 0 2226 4218 3051 35 4 60 > 0 0 0 5727024 1651120 28 254 0 0 0 0 0 0 0 0 0 2126 4224 2982 38 2 60 > 0 0 0 5723184 1648880 93 562 8 2 2 0 0 0 1 1 0 2371 5140 3432 38 3 59 > 0 0 0 5730744 1652512 7 177 26 2 2 0 0 0 1 0 0 2465 4442 3575 36 3 61
至此，此问题得以解决.
本文作者:
eygle,Oracle技术关注者,来自中国最大的Oracle技术论坛 itpub .
www.eygle.com 是作者的个人站点.你可通过 [email protected] 来联系作者.欢迎技术探讨交流以及链接交换.
原文出处:
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