如何定位SQL语句在共享池里用到了哪些chunks

文章由LinuxBoy分享于2019-03-31 05:03:46热评（151）

如何定位SQL语句在共享池里用到了哪些chunks

一条SQL语句执行后，如何找到其在shared pool里占用的chunks，做了一个简单的测试：

---先清空shared pool
alter system flush shared_pool;

---执行sql语句
select * from scott.t1 where username='SYS';

USERNAME USER_ID CREATED
------------------------------ ---------- -----------------
SYS 0 20141110 21:16:12

---这时我们可以看到一个父游标和一个子游标生成了
set linesize 180 pagesize 100 word wrapped
col kglnaobj format a100 word_wrapped
select kglhdadr,kglhdpar,kglnaobj from x$kglob where kglnaobj like 'select * from scott.t1 where username=%';

KGLHDADR KGLHDPAR KGLNAOBJ
---------------- ---------------- ----------------------------------------------------------------------------------------------------
07000001B84F85E8 07000001B8670420 select * from scott.t1 where username='SYS' <---KGLHDADR!=KGLHDPAR，07000001B84F85E8是存放子游标handle的地址
07000001B8670420 07000001B8670420 select * from scott.t1 where username='SYS' <---KGLHDADR=KGLHDPAR，07000001B8670420是存放父游标handle的地址

---以上查出的结果中都是父/子游标handle所在的地址，因为handle会最终指向父/子游标，handle所在的地址也可以看成是指向handle的指针，我们通过shared pool的dump可以找到07000001B8670420这个指向handle的指针，其位于起始地址为7000001b86703f0所在的chunk内，该chunk正是父游标的handle
alter session set tracefile_identifier='level2dmp.txt';
alter system set events 'immediate trace name heapdump level 2';

***tstdb1_ora_3670294_level2dmp.txt trace文件里的信息，我们能看到07000001B8670420这一地址位于"sga heap(1,1)"的EXTENT 1段落中，每个extent的大小称为一个granule size，这里的granule size为16777216 bytes
HEAP DUMP heap name="sga heap(1,1)" desc=700000000056950
extent sz=0xfe0 alt=248 het=32767 rec=9 flg=-126 opc=0
parent=0 owner=0 nex=0 xsz=0x1000000 heap=0
fl2=0x20, nex=0, dsxvers=1, dsxflg=0x0
dsx first ext=0xb8000000
latch set 1 of 4
durations enabled for this heap
reserved granules for root 11 (granule size 16777216)
EXTENT 0 addr=70000019b000000
。。。。省略部分内容

EXTENT 1 addr=7000001b8000000
Chunk 7000001b8000058 sz= 80 perm "perm " alo=80
Chunk 7000001b80000a8 sz= 48 R-freeable "reserved stoppe"
Chunk 7000001b80000d8 sz= 839416 R-free " "
。。。。省略部分内容
Chunk 7000001b866fb90 sz= 1072 recreate "KQR PO " latch=7000001b0d5edb0
Chunk 7000001b866ffc0 sz= 1072 recreate "KQR PO " latch=7000001b0d5edb0
Chunk 7000001b86703f0 sz= 584 recreate "KGLHD " latch=0 <---父游标handle的地址(也即指向父游标handle的指针)包含在起始地址为7000001b86703f0的chunk里，这个chunk的大小为584bytes，类型为KGLHD
Chunk 7000001b8670638 sz= 160 free " "
Chunk 7000001b86706d8 sz= 528 recreate "KGLHD " latch=0
。。。。省略部分内容

---通过父游标的handle所在地址能够关联出父游标heap 0的描述符地址
col KGLNAOBJ format a80
set linesize 190 pagesize 20
select kglhdadr,kglnaobj,kglobhd0 from x$kglob where kglhdadr='07000001B8670420';
KGLHDADR KGLNAOBJ KGLOBHD0
---------------- -------------------------------------------------------------------------------- ----------------
07000001B8670420 select * from scott.t1 where username='SYS' 070000019BB137F0 <---父游标heap 0的描述符(Descriptor)所在地址

---根据上一步得出的heap 0 描述符，找到父游标heap 0，heap 0存放有我们熟悉的object name、dependency table等内容
SYS@tstdb1-SQL> select ksmchcom,ksmchptr,ksmchsiz,ksmchcls,ksmchpar from x$ksmsp where ksmchpar='070000019BB137F0';

KSMCHCOM KSMCHPTR KSMCHSIZ KSMCHCLS KSMCHPAR
---------------- ---------------- ---------- -------- ----------------
KGLH0^f6439b10 0700000195D40F60 4096 recr 070000019BB137F0 <---由此可见父游标heap 0存在于0700000195D40F60地址开始的chunk中，大小为4096 bytes

---为了能看清我们父游标handle与父游标heap 0在内存中的结构，我们使用更为详尽的level对sga进行dump，这个dump命令可没有那么快的完成，dump所耗的时间与你的shared pool大小成正比
alter session set tracefile_identifier='level2050dmp.txt';
alter system set events 'immediate trace name heapdump level 2050';

***从tstdb1_ora_15270042_level2050dmp.txt文件中
>>>>>>>>父游标heap 0所在的chunk信息
。。。。省略部分内容
Chunk 700000195d40f60 sz= 4096 recreate "KGLH0^f6439b10 " latch=0 <---heap 0大小为4096 bytes仅包含一个chunk，由描述符ds=70000019bb137f0指向这个chunk
ds 70000019bb137f0 sz= 4096 ct= 1
Dump of memory from 0x0700000195D40F60 to 0x0700000195D41F60
700000195D40F60 80B38F00 00001001 07000001 95D3FF60 [...............`]
700000195D40F70 00000000 00000000 00000000 00000000 [................]
700000195D40F80 00000000 00000000 00000000 0FFF0AE0 [................]
700000195D40F90 07000001 9BB137F0 00000000 00000000 [......7.........]
700000195D40FA0 40B38F00 00000051 00000000 00000000 [@......Q........]
700000195D40FB0 00000000 00000000 00000050 95D413F8 [...........P....]
700000195D40FC0 C0B38F00 00000001 00000000 00000000 [................]
700000195D40FD0 07000001 95D41BE0 07000001 9BB13868 [..............8h]
700000195D40FE0 00000001 00000000 07000001 95D40F90 [................]
700000195D40FF0 40B38F00 00000BE1 07000001 95D40FA0 [@...............]
700000195D41000 07000001 95D40FA0 00000950 00000000 [...........P....]
700000195D41010 07000001 B8670420 07000001 95D41848 [.....g. .......H]
700000195D41020 00000000 00000000 07000001 9BB137A0 [..............7.]
700000195D41030 00000000 00000000 00000000 00000000 [................]
Repeat 7 times
700000195D410B0 82030003 00000000 10008100 00000000 [................]
700000195D410C0 00000000 00000020 00000000 00000000 [....... ........]
。。。。省略部分内容
Repeat 6 times
700000195D41F40 10B38F00 00000021 07000001 95D41EA8 [.......!........]
700000195D41F50 00000001 09D3E808 00000000 00000000 [................]
Chunk 700000195d41f60 sz= 4096 recreate "KGLH0^5bcbf644 " latch=0

>>>>>>>>父游标heap 0描述符所在的chunk信息
。。。。省略部分内容
Chunk 70000019bb13788 sz= 240 freeable "KGLDA " <---描述符ds=70000019bb137f0地址存在于以70000019bb13788为起始地址的chunk中
Dump of memory from 0x070000019BB13788 to 0x070000019BB13878
70000019BB13780 00B38F00 000000F1 [........]
70000019BB13790 07000001 9BB13730 00000001 09B01958 [......70.......X]
70000019BB137A0 07000001 9BB137F0 07000001 95D410B0 [......7.........]
70000019BB137B0 00000000 01000300 00000000 00000000 [................]
70000019BB137C0 00000FE8 000009D8 07000001 95D41010 [................]
70000019BB137D0 07000001 95D40F90 00000000 00000000 [................]
70000019BB137E0 00000003 0C1F2D58 07000001 B54C6120 [......-X.....La ]
70000019BB137F0 07000000 00000198 00000FE8 00000000 [................]
70000019BB13800 07000001 9BB137A0 07000001 95D40F90 [......7.........]
70000019BB13810 07000001 95D40FF0 00000000 00000000 [................]
70000019BB13820 00000000 00000000 09020100 00000000 [................]
70000019BB13830 00000000 00000000 00000FD0 4B474C48 [............KGLH]
70000019BB13840 305E6636 34333962 31300026 7FFF0038 [0^f6439b10.&...8]
70000019BB13850 00307FFF 00000000 01030000 00000000 [.0..............]
70000019BB13860 00000000 00000000 07000001 95D40FD0 [................]
70000019BB13870 07000001 95D41BE0 [........]
Chunk 70000019bb13878 sz= 560 recreate "KQR PO " latch=7000001b0d5f050
Dump of memory from 0x070000019BB13878 to 0x070000019BB13AA8

---通过指向子游标handle地址的指针07000001B84F85E8能够关联出子游标heap 0的描述符地址
col KGLNAOBJ format a80
set linesize 190 pagesize 20
select kglhdadr,kglnaobj,kglobhd0 from x$kglob where kglhdadr='07000001B84F85E8';
KGLHDADR KGLNAOBJ KGLOBHD0
---------------- -------------------------------------------------------------------------------- ----------------
07000001B84F85E8 select * from scott.t1 where username='SYS' 07000001B84F8530 <---子游标heap 0的描述符(Descriptor)所在chunk起始地址

***在tstdb1_ora_15270042_level2050dmp.txt文件中可以找到包含07000001B84F8530和07000001B84F85E8地址所在的段落：
Chunk 7000001b84f84c8 sz= 240 freeable "KGLDA " <---子游标heap 0描述符的地址所在chunk起始地址
Dump of memory from 0x07000001B84F84C8 to 0x07000001B84F85B8
7000001B84F84C0 00B38F00 000000F1 [........]
7000001B84F84D0 07000001 B84F83D8 00000001 09B01958 [.....O.........X]
7000001B84F84E0 07000001 B84F8530 07000001 95D400B0 [.....O.0........]
7000001B84F84F0 00000000 01000300 07000001 A885E598 [................]
7000001B84F8500 00000FE8 00000A60 07000001 95D40010 [.......`........]
7000001B84F8510 07000001 95D3FF90 00000000 00000000 [................]
7000001B84F8520 00000003 0C1F2D58 07000001 B54C6120 [......-X.....La ]
7000001B84F8530 07000000 00000198 00000FE8 00000000 [................]
7000001B84F8540 07000001 B84F84E0 07000001 95D3FF90 [.....O..........]
7000001B84F8550 07000001 95D3FFF0 00000000 00000000 [................]
7000001B84F8560 00000000 00000000 09020100 00000000 [................]
7000001B84F8570 00000000 00000000 00000FD0 4B474C48 [............KGLH]
7000001B84F8580 305E6636 34333962 31300026 7FFF0038 [0^f6439b10.&...8]
7000001B84F8590 00307FFF 00000000 01030000 00000000 [.0..............]
7000001B84F85A0 00000000 00000000 07000001 95D3FFD0 [................]
7000001B84F85B0 07000001 95D40A10 [........]
Chunk 7000001b84f85b8 sz= 352 recreate "KGLHD " latch=0 <---指向子游标handle地址的指针，它和上面的描述符恰巧在相邻的两个chunk内
Dump of memory from 0x07000001B84F85B8 to 0x07000001B84F8718
7000001B84F85B0 80B38F00 00000161 [.......a]
7000001B84F85C0 07000001 B84F84C8 00000000 00000000 [.....O..........]
7000001B84F85D0 00000000 00000000 00000000 00000000 [................]
7000001B84F85E0 00000000 00500800 07000001 B84F85E8 [.....P.......O..]
7000001B84F85F0 07000001 B84F85E8 07000001 95D40010 [.....O..........]
7000001B84F8600 00000000 00000000 00000000 10012111 [..............!.]
7000001B84F8610 00010000 00010000 00010001 00000001 [................]
7000001B84F8620 00000000 00000001 00000100 00000000 [................]
7000001B84F8630 00000000 00000000 00000000 00000000 [................]
7000001B84F8640 00000000 00000000 07000001 B84F8648 [.............O.H]
7000001B84F8650 07000001 B84F8648 07000001 B84F8658 [.....O.H.....O.X]
7000001B84F8660 07000001 B84F8658 07000001 B84F8668 [.....O.X.....O.h]
7000001B84F8670 07000001 B84F8668 07000001 B84F8678 [.....O.h.....O.x]
7000001B84F8680 07000001 B84F8678 07000001 95D41918 [.....O.x........]
7000001B84F8690 07000001 95D41918 00000000 00000000 [................]
7000001B84F86A0 00000000 00000000 00000000 00000000 [................]
7000001B84F86B0 00000000 00000000 07000001 B8670550 [.............g.P]
7000001B84F86C0 07000001 B84F86C0 07000001 B84F86C0 [.....O.......O..]
7000001B84F86D0 07000001 B84F86D0 07000001 B84F86D0 [.....O.......O..]
7000001B84F86E0 00000000 00000000 07000001 B0EA1A60 [...............`]
7000001B84F86F0 00000000 00000000 00000000 00000000 [................]
7000001B84F8700 00000001 00000002 00000000 00000000 [................]
7000001B84F8710 00000000 00000000 [........]

---根据上一步得出的heap 0 描述符，找到子游标heap 0所在chunk
SYS@tstdb1-SQL> select ksmchcom,ksmchptr,ksmchsiz,ksmchcls,ksmchpar from x$ksmsp where ksmchpar='07000001B84F8530';

KSMCHCOM KSMCHPTR KSMCHSIZ KSMCHCLS KSMCHPAR
---------------- ---------------- ---------- -------- ----------------
KGLH0^f6439b10 0700000195D3FF60 4096 recr 07000001B84F8530 <---由此可见子游标heap 0存在于0700000195D3FF60地址开始的chunk中，大小为4096 bytes

***在tstdb1_ora_15270042_level2050dmp.txt文件中可以找到包含700000195D3FF60这个地址的chunk
Chunk 700000195d3ff60 sz= 4096 recreate "KGLH0^f6439b10 " latch=0
ds 7000001b84f8530 sz= 4096 ct= 1
Dump of memory from 0x0700000195D3FF60 to 0x0700000195D40F60
700000195D3FF60 80B38F00 00001001 07000001 95D3EF60 [...............`]
700000195D3FF70 07000001 99E4EAC0 07000001 B89F3648 [..............6H]
700000195D3FF80 00000000 00000000 00000000 0FFF0200 [................]
700000195D3FF90 07000001 B84F8530 00000000 00000000 [.....O.0........]
700000195D3FFA0 40B38F00 00000051 00000000 00000000 [@......Q........]
700000195D3FFB0 00000000 00000000 00000050 00000000 [...........P....]
700000195D3FFC0 C0B38F00 00000001 00000000 00000000 [................]
700000195D3FFD0 07000001 95D40A10 07000001 B84F85A8 [.............O..]
700000195D3FFE0 00000001 00000000 07000001 95D3FF90 [................]
700000195D3FFF0 40B38F00 00000A11 07000001 95D3FFA0 [@...............]
700000195D40000 07000001 95D3FFA0 00000898 00000000 [................]
700000195D40010 07000001 B84F85E8 07000001 95D403D0 [.....O..........]
700000195D40020 00000000 00000000 07000001 B84F84E0 [.............O..]
。。。。省略部分内容

---以同样的方法得到子游标heap 6所在chunk
select kglhdadr,kglnaobj,kglobhd6 from x$kglob where kglhdadr='07000001B84F85E8';
KGLHDADR KGLNAOBJ KGLOBHD6
---------------- -------------------------------------------------------------------------------- ----------------
07000001B84F85E8 select * from scott.t1 where username='SYS' 0700000195D416E8 <---子游标heap 6的描述符(Descriptor)所在地址

select ksmchcom,ksmchptr,ksmchsiz,ksmchcls,ksmchpar from x$ksmsp where ksmchpar='0700000195D416E8';

KSMCHCOM KSMCHPTR KSMCHSIZ KSMCHCLS KSMCHPAR
---------------- ---------------- ---------- -------- ----------------
SQLA^f6439b10 0700000199EA5AB0 4096 recr 0700000195D416E8 <---heap 6含有2个大小都是4096 bytes的chunk
SQLA^f6439b10 0700000199E9FAB0 4096 freeabl 0700000195D416E8

***在tstdb1_ora_15270042_level2050dmp.txt文件中可以找到包含0700000195D416E8 chunk的段落
Chunk 700000199ea5ab0 sz= 4096 recreate "SQLA^f6439b10 " latch=0
ds 700000195d416e8 sz= 8192 ct= 2
700000199e9fab0 sz= 4096
Dump of memory from 0x0700000199EA5AB0 to 0x0700000199EA6AB0
700000199EA5AB0 80B38F00 00001001 07000001 99EA4AB0 [..............J.]
700000199EA5AC0 07000001 95D3DF70 07000001 B8796E90 [.......p.....yn.]
700000199EA5AD0 00000000 00000000 00000000 0FFF0279 [...............y]
700000199EA5AE0 07000001 95D416E8 00000000 00000000 [................]
700000199EA5AF0 40B38F00 00000051 00000000 00000000 [@......Q........]
700000199EA5B00 00000000 00000000 00000050 000000D8 [...........P....]
700000199EA5B10 C0B38F00 00000001 00000000 00000000 [................]
700000199EA5B20 07000001 95D41760 07000001 95D41760 [.......`.......`]
700000199EA5B30 00000001 00000000 07000001 99EA5AE0 [..............Z.]
700000199EA5B40 00B38F00 00000069 07000001 99EA5AF0 [.......i......Z.]
700000199EA5B50 00000001 0B018734 01000000 00000000 [.......4........]

简单总结一下：
定位到父游标heap 0：
指向父游标handle的指针：07000001B8670420(类型为KGLHD，x$kglob)->父游标heap 0的描述符070000019BB137F0(类型为KGLDA，x$kglob)->父游标heap 0所在chunk地址：0700000195D40F60(类型为KGLH0，x$ksmsp)

找到父游标下的子游标，可以使用：
select kglhdadr,kglnaobj from x$kglob where kglnaobj like 'select * from scott.t1 where username=%' and kglhdadr!=kglhdpar;

定位到子游标heap 0、heap 6:
子游标handle的指针：07000001B84F85E8(类型为KGLHD，x$kglob)->子游标heap 0的描述符07000001B84F8530(类型为KGLDA，x$kglob)->heap 0所在chunk地址：0700000195D3FF60(类型为KGLH0，x$ksmsp)
子游标handle的指针：07000001B84F85E8(类型为KGLHD，x$kglob)->子游标heap 6的描述符0700000195D416E8(包含在父游标的heap 0所在的chunk里，x$kglob)->heap 6所在chunk地址：0700000199EA5AB0、0700000199E9FAB0(类型为SQLA，x$ksmsp)

本文永久更新链接地址：

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如何定位SQL语句在共享池里用到了哪些chunks