[20180813]重新整理共享池與父子游標.txt

[20180813]重新整理共享池與父子游標.txt

--//測試重新整理共享池與父子游標含有那些資訊儲存在共享池.
--//自己最近遇到的問題,感覺自己以前理解有點亂,測試看看.

1.環境
SCOTT@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.測試:

--//session 1:
select * from dept where deptno=10;
--//確定sql_id=4xamnunv51w9j,可以查詢v$sql檢視確定.

--//session 2:
SYS@book> @ &r/sharepool/shp4 4xamnunv51w9j 0
TEXT           KGLHDADR         KGLHDPAR         C40                                        KGLHDLMD   KGLHDPMD KGLOBHD0         KGLOBHD6           KGLOBHS0   KGLOBHS6   KGLOBT16   N0_6_16        N20   KGLNAHSH KGLOBT03        KGLOBT09
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游標控制程式碼地址 000000007D9134A0 000000007D7110E0 select * from dept where deptno=10                1          0 000000007D6F2250 000000007BFF1138       4488      12144       3067     19699      19699  911274289 4xamnunv51w9j          0
父遊標控制程式碼地址 000000007D7110E0 000000007D7110E0 select * from dept where deptno=10                1          0 000000007D9E7608 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535
--//全部父子游標,父堆0.子堆0,6都在.KGLHDLMD=1.當前session 1,執行完該條語句,11g下游標不會釋放.

SYS@book> alter system flush shared_pool;
System altered.

SYS@book> @ &r/sharepool/shp4 4xamnunv51w9j 0
TEXT           KGLHDADR         KGLHDPAR         C40                                        KGLHDLMD   KGLHDPMD KGLOBHD0         KGLOBHD6           KGLOBHS0   KGLOBHS6   KGLOBT16   N0_6_16        N20   KGLNAHSH KGLOBT03        KGLOBT09
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游標控制程式碼地址 000000007D9134A0 000000007D7110E0 select * from dept where deptno=10                1          0 00               00                        0          0       3067      3067       3067  911274289 4xamnunv51w9j          0
父遊標控制程式碼地址 000000007D7110E0 000000007D7110E0 select * from dept where deptno=10                1          0 000000007D9E7608 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//父子游標,父遊標堆0,子游標都沒有清除.並且KGLHDLMD=1
--//子游標堆0,子游標堆6清除.
--//當前執行的語句,遊標不會關閉,重新整理共享池,並不能父子游標,父遊標堆0,子游標.
--//是否可以這麼理解KGLHDLMD=1的情況下,不會清除全部資訊.

--//session 1:
SCOTT@book> select sysdate from dual;
SYSDATE
-------------------
2018-08-14 09:00:11

--//session 2:
SYS@book> alter system flush shared_pool;
System altered.

SYS@book> @ &r/sharepool/shp4 4xamnunv51w9j 0
no rows selected

--//可以發現游標已經全部清除.因為session 1當前執行的是 select sysdate from dual;.
--//sql_id=4xamnunv51w9j的遊標已經關閉.這樣重新整理共享池,可以完全清除.
--//忘記在重新整理前看看遊標的情況,補充測試3.

3.測試:
--//session 1:
select * from dept where deptno=10;
select sysdate from dual;
--//注意當前語句不是select * from dept where deptno=10;.

--//session 2:
SYS@book> @ &r/sharepool/shp4 4xamnunv51w9j 0
TEXT           KGLHDADR         KGLHDPAR         C40                                        KGLHDLMD   KGLHDPMD KGLOBHD0         KGLOBHD6           KGLOBHS0   KGLOBHS6   KGLOBT16   N0_6_16        N20   KGLNAHSH KGLOBT03        KGLOBT09
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游標控制程式碼地址 000000007D8A5B98 000000007DB3C798 select * from dept where deptno=10                0          0 000000007D72DD88 000000007C9A8358       4520      12144       3067     19731      19731  911274289 4xamnunv51w9j          0
父遊標控制程式碼地址 000000007DB3C798 000000007DB3C798 select * from dept where deptno=10                0          0 000000007DAFF9F0 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//全部父子游標,父堆0.子堆0,6都在.KGLHDLMD=0.

SYS@book> alter system flush shared_pool;
System altered.

SYS@book> @ &r/sharepool/shp4 4xamnunv51w9j 0
no rows selected

4.測試:
--//測試會話快取游標的情況.
--//session 1:
SCOTT@book> show parameter session_cached_cursors
NAME                   TYPE    VALUE
---------------------- ------- -----
session_cached_cursors integer 50

select * from dept where deptno=10;
select sysdate from dual;
select * from dept where deptno=10;
select sysdate from dual;
select * from dept where deptno=10;
select sysdate from dual;
select * from dept where deptno=10;
select sysdate from dual;
--//執行3次以上,注意最後一條語句是select sysdate from dual;

--//session 2:
SYS@book> @ &r/sharepool/shp4 4xamnunv51w9j 0
TEXT           KGLHDADR         KGLHDPAR         C40                                        KGLHDLMD   KGLHDPMD KGLOBHD0         KGLOBHD6           KGLOBHS0   KGLOBHS6   KGLOBT16   N0_6_16        N20   KGLNAHSH KGLOBT03        KGLOBT09
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游標控制程式碼地址 000000007D4BB278 000000007D4BB608 select * from dept where deptno=10                1          0 000000007D4BB1C0 000000007BA63988       4528      12144       3067     19739      19739  911274289 4xamnunv51w9j          0
父遊標控制程式碼地址 000000007D4BB608 000000007D4BB608 select * from dept where deptno=10                1          0 000000007D4BF948 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//執行3次以後,KGLHDLMD=1.
--//你可以在每次執行select sysdate from dual;檢視sql_id=4xamnunv51w9j游標情況.
--//僅僅第3次後KGLHDLMD=1.

SYS@book> alter system flush shared_pool;
System altered.

SYS@book> @ &r/sharepool/shp4 4xamnunv51w9j 0
TEXT           KGLHDADR         KGLHDPAR         C40                                        KGLHDLMD   KGLHDPMD KGLOBHD0         KGLOBHD6           KGLOBHS0   KGLOBHS6   KGLOBT16   N0_6_16        N20   KGLNAHSH KGLOBT03        KGLOBT09
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游標控制程式碼地址 000000007D4BB278 000000007D4BB608 select * from dept where deptno=10                1          0 00               00                        0          0       3067      3067       3067  911274289 4xamnunv51w9j          0
父遊標控制程式碼地址 000000007D4BB608 000000007D4BB608 select * from dept where deptno=10                1          0 000000007D4BF948 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//父子游標,父遊標堆0,子游標都沒有清除.並且KGLHDLMD=1
--//子游標堆0,子游標堆6清除.
--//當前執行的語句不是該條,但是當會話快取遊標以後,重新整理共享池,並不能清除父子游標,父遊標堆0,子游標.
--//也就是重新整理共享池無法完全清除會話快取的游標.

--//附上shp4.sql指令碼:
$ cat sharepool/shp4.sql
column N0_6_16 format 99999999
SELECT DECODE (kglhdadr,
               kglhdpar, '父遊標控制程式碼地址',
               '子游標控制程式碼地址')
          text,
       kglhdadr,
       kglhdpar,
       substr(kglnaobj,1,40) c40,
           KGLHDLMD,
           KGLHDPMD,
--         kglhdivc,
       kglobhd0,
       kglobhd6,
       kglobhs0,kglobhs6,kglobt16,
       kglobhs0+kglobhs6+kglobt16 N0_6_16,
           kglobhs0+kglobhs1+kglobhs2+kglobhs3+kglobhs4+kglobhs5+kglobhs6+kglobt16 N20,
           kglnahsh,
           kglobt03 ,
           kglobt09
  FROM x$kglob
 WHERE kglobt03 = '&1'  or kglhdpar='&1' or kglhdadr='&1' or KGLNAHSH= &2;