[20210220]gdb跟踪逻辑读2.txt

来源：这里教程网时间：2026-03-03 16:28:16 作者：

[20210220]gdb跟踪逻辑读2.txt --//有了昨天的测试,链接如下: --//http://blog.itpub.net/267265/viewspace-2757857/ =>[20210219]全表扫描逻辑读问题.txt --//http://blog.itpub.net/267265/viewspace-2757859/ => [20210220]全索引扫描快速索引扫描的逻辑读.txt --//知道这些函数,就可以写出gdb脚本,跟踪那些逻辑读.查看register,以及某些寄存器的地址就可以知道带入的参数,我主要想知道读那 --//些数据块. 过程略.我仅仅贴出gdb脚本,肯定存在许多错误. 1.环境: SYS@book> @ ver1 PORT_STRING VERSION BANNER ------------------------------ -------------- -------------------------------------------------------------------------------- x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production 2.gdb脚本: $ cat gdb/fetch.gdb break sntpread set pagination off commands silent set var a=0x0 set var b=0x0 continue end break kteinpscan set pagination off commands silent shell echo -n $( date +"%Y/%m/%d %T.%N : ") printf "kteinpscan 0x%x\n", *($rdi+4) continue end break kdst_fetch if *($rsi+28) != 0 set pagination off commands silent shell echo -n $( date +"%Y/%m/%d %T.%N : ") printf "kdst_fetch 0x%x\n", *($rsi+28) continue end break kteinmap set pagination off commands silent shell echo -n $( date +"%Y/%m/%d %T.%N : ") printf "kteinmap 0x%x\n", *($rdi+4) continue end #set var a=0x0 break kdifxs if *($rdi+28) != a set pagination off commands silent shell echo -n $( date +"%Y/%m/%d %T.%N : ") printf "kdifxs 0x%x\n", *($rdi+28) set var a= *($rdi+28) continue end #set var b=0x0 break kdsgrp if *($rdi+28) != b set pagination off commands silent shell echo -n $( date +"%Y/%m/%d %T.%N : ") printf "kdsgrp 0x%x\n", *($rdi+28) set var b= *($rdi+28) continue end #break kdircys #set pagination off # commands # silent # shell echo -n $( date +"%Y/%m/%d %T.%N : ") # printf "kdircys 0x%x\n", *($rdi+4) # continue # end #break qeilbk #set pagination off # commands # silent # shell echo -n $( date +"%Y/%m/%d %T.%N : ") # printf "qeilbk 0x%x\n", *($rsi+28) # continue # end --//说明:qeilbk,kdircys函数无法跟踪,我不知道为什么? kdifxs 视乎每取1行调用1次,改写成上面的样子.逻辑读统计肯定有问题的.特 --//别是设置array很小的情况.另外kdsgrp类似,估计临近的块算1个逻辑读. --//另外我还遇到kdst_fetch *($rsi+28) = 0的情况.我不跟踪这样的情况. --//我多设置断点break sntpread,主要目的是为了初始话a,b变量值为0,不然下次执行的sql记录的是新的值,这样可能会漏掉一些信息. 3.测试前准备与说明: --//注意测试前sql语句最好多次避免一些递归,还有一些大表可能采用直接路径读,绕过了oracle的数据缓存,自然看不到. --//还有唯一索引,索引root节点,分支节点跟踪不到,或者使用的函数我不知道暂时放弃. --//另外测试没有考虑读undo的情况,先暂时放弃. --//sesion 1: SCOTT@book> @ spid SID SERIAL# PROCESS SERVER SPID PID P_SERIAL# C50 ---------- ---------- ------------------------ --------- ------ ------- ---------- -------------------------------------------------- 295 5 46722 DEDICATED 46723 21 3 alter system kill session '295,5' immediate; --//sesion 2: $ gdb -p 46723 -x ~/gdb/fetch.gdb ... Breakpoint 1 at 0x994df72 Breakpoint 2 at 0xfcafda Breakpoint 3 at 0x947da78 Breakpoint 4 at 0xfc97f0 Breakpoint 5 at 0x95ed0ca Breakpoint 6 at 0x94471a4 (gdb) 4.测试: --//测试结果以后面的gdb脚本为准. --//全表扫描: select * from emp; --//跟踪文件: *** 2021-02-20 15:34:21.723 pin ktewh26: kteinpscan dba 0x1000092:4 time 2565022127 pin kdswh11: kdst_fetch dba 0x1000093:1 time 2565028245 pin kdswh11: kdst_fetch dba 0x1000094:1 time 2565033596 pin kdswh11: kdst_fetch dba 0x1000095:1 time 2565038986 pin kdswh11: kdst_fetch dba 0x1000096:1 time 2565044408 pin kdswh11: kdst_fetch dba 0x1000097:1 time 2565049667 pin kdswh11: kdst_fetch dba 0x1000097:1 time 2565070280 --//gdb: 2021/02/20 15:34:57.544337510 :kteinpscan 0x1000092 2021/02/20 15:34:57.549826022 :kteinmap 0x1000092 2021/02/20 15:34:57.555883105 :kdst_fetch 0x1000093 2021/02/20 15:34:57.561262392 :kdst_fetch 0x1000094 2021/02/20 15:34:57.566930570 :kdst_fetch 0x1000095 2021/02/20 15:34:57.572255586 :kdst_fetch 0x1000096 2021/02/20 15:34:57.591945115 :kdst_fetch 0x1000097 2021/02/20 15:34:57.597271327 :kdst_fetch 0x1000097 --//注extent仅仅1个的情况下,"_trace_pin_time"=1跟踪看不到kteinmap,实际逻辑读是7. --//INDEX FULL SCAN: select count(*) from emp; --//跟踪文件: *** 2021-02-20 15:35:35.428 pin qeilwhrp: qeilbk dba 0x100009b:1 time 2638727352 --//gdb: 2021/02/20 15:36:05.752024571 :kdifxs 0x100009b --//INDEX FAST FULL SCAN select /*+ index_ffs(emp) */ count(*) from emp; --//跟踪文件: *** 2021-02-20 15:36:45.413 pin ktewh26: kteinpscan dba 0x100009a:4 time 2708712237 pin kdiwh100: kdircys dba 0x100009b:1 time 2708717602 --//gdb显示: 2021/02/20 15:36:45.400717820 :kteinpscan 0x100009a 2021/02/20 15:36:45.406515456 :kteinmap 0x100009a 2021/02/20 15:36:45.411622200 :kteinpscan 0x100009a 2021/02/20 15:36:45.416993772 :kteinmap 0x100009a --// TABLE ACCESS BY USER ROWID select * from emp where rowid='AAAVREAAEAAAACXAAA'; --//跟踪文件: *** 2021-02-20 15:38:29.342 pin kdswh05: kdsgrp dba 0x1000097:1 time 2812641841 --//gdb显示: 2021/02/20 15:38:29.334660926 :kdsgrp 0x1000097 --//这个结果使用上面的gdb脚本: --//INDEX RANGE SCAN SCOTT@book> select * from emp where empno between 7788 and 7900; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- ------------------- ---------- ---------- ---------- 7788 SCOTT ANALYST 7566 1987-04-19 00:00:00 3000 20 7839 KING PRESIDENT 1981-11-17 00:00:00 5000 10 7844 TURNER SALESMAN 7698 1981-09-08 00:00:00 1500 0 30 7876 ADAMS CLERK 7788 1987-05-23 00:00:00 1100 20 7900 JAMES CLERK 7698 1981-12-03 00:00:00 950 30 --//跟踪文件: *** 2021-02-20 15:46:16.744 pin qeilwhrp: qeilbk dba 0x100009b:1 time 3280043412 pin kdswh05: kdsgrp dba 0x1000097:1 time 3280070000 pin kdiwh16: kdifxs dba 0x100009b:1 time 3280096298 pin kdswh05: kdsgrp dba 0x1000097:1 time 3280108554 --//gdb显示: 2021/02/20 15:46:16.749466318 :kdifxs 0x100009b 2021/02/20 15:46:16.762301302 :kdsgrp 0x1000097 2021/02/20 15:46:16.788847316 :kdifxs 0x100009b 2021/02/20 15:46:16.801327592 :kdsgrp 0x1000097 Plan hash value: 169057108 -------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows |E-Bytes| Cost (%CPU)| E-Time | A-Rows | A-Time | Buffers | -------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | | 2 (100)| | 5 |00:00:00.03 | 4 | | 1 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 5 | 190 | 2 (0)| 00:00:01 | 5 |00:00:00.03 | 4 | |* 2 | INDEX RANGE SCAN | PK_EMP | 1 | 5 | | 1 (0)| 00:00:01 | 5 |00:00:00.01 | 2 | -------------------------------------------------------------------------------------------------------------------------------- --//再找一条sql语句测试看看. SCOTT@book> select /*+ index(t) */ CREATED from t where owner='SCOTT'; Plan hash value: 3696261165 -------------------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows |E-Bytes| Cost (%CPU)| E-Time | A-Rows | A-Time | Buffers | -------------------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | | 2237 (100)| | 22 |00:00:00.20 | 18 | | 1 | TABLE ACCESS BY INDEX ROWID| T | 1 | 2923 | 40922 | 2237 (0)| 00:00:27 | 22 |00:00:00.20 | 18 | |* 2 | INDEX RANGE SCAN | I_T_OWNER_OBJ_NAME | 1 | 2923 | | 19 (0)| 00:00:01 | 22 |00:00:00.02 | 4 | -------------------------------------------------------------------------------------------------------------------------------------------- --//跟踪文件: *** 2021-02-20 15:51:01.925 pin qeilwhnp: qeilbk dba 0x1000e8f:1 time 3565224759 pin kdswh05: kdsgrp dba 0x100074c:1 time 3565254780 pin kdiwh16: kdifxs dba 0x1000e8f:1 time 3565290060 pin kdswh05: kdsgrp dba 0x1000755:1 time 3565302136 pin kdswh05: kdsgrp dba 0x100074c:1 time 3565314752 pin kdswh05: kdsgrp dba 0x1000755:1 time 3565327400 pin kdswh05: kdsgrp dba 0x100074c:1 time 3565340047 pin kdswh05: kdsgrp dba 0x1000755:1 time 3565354194 pin kdswh05: kdsgrp dba 0x100074d:1 time 3565367977 pin kdswh05: kdsgrp dba 0x1000755:1 time 3565380604 pin kdswh05: kdsgrp dba 0x100074c:1 time 3565394572 pin kdswh05: kdsgrp dba 0x1000755:1 time 3565409295 pin kdswh05: kdsgrp dba 0x100074c:1 time 3565423088 pin kdswh05: kdsgrp dba 0x100074d:1 time 3565436764 pin kdswh05: kdsgrp dba 0x100074c:1 time 3565450436 pin kdswh05: kdsgrp dba 0x1000755:1 time 3565463067 --//gdb显示: 2021/02/20 15:51:26.825408913 :kdifxs 0x1000e8f 2021/02/20 15:51:26.837967584 :kdsgrp 0x100074c 2021/02/20 15:51:26.864101083 :kdifxs 0x1000e8f 2021/02/20 15:51:26.876209013 :kdsgrp 0x1000755 2021/02/20 15:51:26.888767163 :kdsgrp 0x100074c 2021/02/20 15:51:26.901400712 :kdsgrp 0x1000755 2021/02/20 15:51:26.913979815 :kdsgrp 0x100074c 2021/02/20 15:51:26.928021294 :kdsgrp 0x1000755 2021/02/20 15:51:26.941792597 :kdsgrp 0x100074d 2021/02/20 15:51:26.954469410 :kdsgrp 0x1000755 2021/02/20 15:51:26.968166227 :kdsgrp 0x100074c 2021/02/20 15:51:26.982954562 :kdsgrp 0x1000755 2021/02/20 15:51:26.996717134 :kdsgrp 0x100074c 2021/02/20 15:51:27.015716039 :kdsgrp 0x100074d 2021/02/20 15:51:27.029494844 :kdsgrp 0x100074c 2021/02/20 15:51:27.042042161 :kdsgrp 0x1000755 --//这样看到的逻辑读就很接近了. --//0x1000e8f = set dba 4,3727 = alter system dump datefile 4 block 3727 = 16780943 SYS@book> @ which_obj 4 3727 SYS@book> @ prxx ============================== OWNER : SCOTT SEGMENT_NAME : I_T_OWNER_OBJ_NAME PARTITION_NAME : SEGMENT_TYPE : INDEX TABLESPACE_NAME : USERS EXTENT_ID : 17 FILE_ID : 4 BLOCK_ID : 3712 BYTES : 1048576 BLOCKS : 128 RELATIVE_FNO : 4 PL/SQL procedure successfully completed. 总结: --//纯粹无聊,自己也不熟悉gdb,不要在生产系统做这样的测试与操作!! --//写这么长,主要记录自己学习和分析的过程,实际上的测试过程远比上面写的要曲折复杂的多,经过多次反复.

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