[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;