[20180813]刷新共享池与父子游标.txt

[20180813]刷新共享池与父子游标.txt

--//测试刷新共享池与父子游标含有那些信息保存在共享池.
--//自己最近遇到的问题,感觉自己以前理解有点乱,测试看看.

1.环境
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.测试:

--//session 1:
select * from dept where deptno=10;
--//确定sql_id=4xamnunv51w9j,可以查询v$sql视图确定.

--//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
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游标句柄地址 000000007D9134A0 000000007D7110E0 select * from dept where deptno=10                1          0 000000007D6F2250 000000007BFF1138       4488      12144       3067     19699      19699  911274289 4xamnunv51w9j          0
父游标句柄地址 000000007D7110E0 000000007D7110E0 select * from dept where deptno=10                1          0 000000007D9E7608 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535
--//全部父子光标,父堆0.子堆0,6都在.KGLHDLMD=1.当前session 1,执行完该条语句,11g下游标不会释放.

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
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游标句柄地址 000000007D9134A0 000000007D7110E0 select * from dept where deptno=10                1          0 00               00                        0          0       3067      3067       3067  911274289 4xamnunv51w9j          0
父游标句柄地址 000000007D7110E0 000000007D7110E0 select * from dept where deptno=10                1          0 000000007D9E7608 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//父子游标,父游标堆0,子游标都没有清除.并且KGLHDLMD=1
--//子游标堆0,子游标堆6清除.
--//当前执行的语句,游标不会关闭,刷新共享池,并不能父子游标,父游标堆0,子游标.
--//是否可以这么理解KGLHDLMD=1的情况下,不会清除全部信息.

--//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

--//可以发现光标已经全部清除.因为session 1当前执行的是 select sysdate from dual;.
--//sql_id=4xamnunv51w9j的游标已经关闭.这样刷新共享池,可以完全清除.
--//忘记在刷新前看看游标的情况,补充测试3.

3.测试:
--//session 1:
select * from dept where deptno=10;
select sysdate from dual;
--//注意当前语句不是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
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游标句柄地址 000000007D8A5B98 000000007DB3C798 select * from dept where deptno=10                0          0 000000007D72DD88 000000007C9A8358       4520      12144       3067     19731      19731  911274289 4xamnunv51w9j          0
父游标句柄地址 000000007DB3C798 000000007DB3C798 select * from dept where deptno=10                0          0 000000007DAFF9F0 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//全部父子光标,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.测试:
--//测试会话缓存光标的情况.
--//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;
--//执行3次以上,注意最后一条语句是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
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游标句柄地址 000000007D4BB278 000000007D4BB608 select * from dept where deptno=10                1          0 000000007D4BB1C0 000000007BA63988       4528      12144       3067     19739      19739  911274289 4xamnunv51w9j          0
父游标句柄地址 000000007D4BB608 000000007D4BB608 select * from dept where deptno=10                1          0 000000007D4BF948 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//执行3次以后,KGLHDLMD=1.
--//你可以在每次执行select sysdate from dual;查看sql_id=4xamnunv51w9j光标情况.
--//仅仅第3次后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
-------------- ---------------- ---------------- ---------------------------------------- ---------- ---------- ---------------- ---------------- ---------- ---------- ---------- --------- ---------- ---------- ------------- ----------
子游标句柄地址 000000007D4BB278 000000007D4BB608 select * from dept where deptno=10                1          0 00               00                        0          0       3067      3067       3067  911274289 4xamnunv51w9j          0
父游标句柄地址 000000007D4BB608 000000007D4BB608 select * from dept where deptno=10                1          0 000000007D4BF948 00                     4720          0          0      4720       4720  911274289 4xamnunv51w9j      65535

--//父子游标,父游标堆0,子游标都没有清除.并且KGLHDLMD=1
--//子游标堆0,子游标堆6清除.
--//当前执行的语句不是该条,但是当会话缓存游标以后,刷新共享池,并不能清除父子游标,父游标堆0,子游标.
--//也就是刷新共享池无法完全清除会话缓存的光标.

--//附上shp4.sql脚本:
$ cat sharepool/shp4.sql
column N0_6_16 format 99999999
SELECT DECODE (kglhdadr,
               kglhdpar, '父游标句柄地址',
               '子游标句柄地址')
          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;