SHARE POOL利用堆（HEAP)的内存管理方式管理，在物理上由多个内存区（EXTENT)组成，内存区又由多个不同大小的CHUNK组成。而CHUNK又有可重用和空闲之分，并且它们分别有LRU LIST、FREE LIST、RESERVED LIST串联起来。
堆管理
Shared Pool是利用堆内存管理方式管理的（KGH:Kernel Generic Heap).从Oracle 9i开始，可以有多个最高级堆（TOP-LEVLE HEAP)，最高级堆可以分成多个副堆，副堆下面还拥有子堆。堆和副对结构基本相同。从物理上讲，一个堆由多个内存区已link list的形式连接组成。一个内存区物理上使用一个Granule，一个内存区由多个chunk组成，所以chunk是heap的最小内存单位。
Chunk的使用情况可由X$KSMSP内部视图查看。每个堆头上则包含了可使用的chunk列表和已使用的chunk列表。通过dump heap命令可以在trace文件中观察heap和extent的关系。
alter system set events 'immediate trace name heapdump level 2';
案例：
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SQL> select name,bytes/
1024
/
1024
from
v$sgainfo;
NAME BYTES/
1024
/
1024
-------------------------------- ---------------
Fixed SGA Size
1.27566528
Redo Buffers
5.59765625
Buffer Cache Size
180
Shared Pool Size
104
Large Pool Size
4
Java Pool Size
4
Streams Pool Size
0
Shared IO Pool Size
0
Granule Size
4
Maximum SGA Size
498.875
Startup overhead
in
Shared Pool
52
NAME BYTES/
1024
/
1024
-------------------------------- ---------------
Free SGA Memory Available
200
12
rows selected.
[oracle@node1 ~]$ more /u01/app/oracle/diag/rdbms/prod/prod/trace/prod_ora_14983.trc
Trace file /u01/app/oracle/diag/rdbms/prod/prod/trace/prod_ora_14983.trc
Oracle Database 11g Enterprise Edition Release
11.2.
0.1.
0
- Production
With the Partitioning, OLAP, Data Mining
and
Real Application Testing options
ORACLE_HOME = /u01/app/oracle/product/
11.2.
0
/db_1
System name: Linux
Node name: node1
Release:
2.6.
18
-194.
el5
Version: #
1
SMP Tue Mar
16
21
:
52
:
43
EDT
2010
Machine: i686
Instance name: prod
Redo thread mounted by
this
instance:
1
Oracle process number:
32
Unix process pid:
14983
, image: oracle@node1 (TNS V1-V3)
***
2014
-07
-02
14
:
58
:
47.532
*** SESSION ID:(
32.758
)
2014
-07
-02
14
:
58
:
47.532
*** CLIENT ID:()
2014
-07
-02
14
:
58
:
47.532
*** SERVICE NAME:(SYS$USERS)
2014
-07
-02
14
:
58
:
47.532
*** MODULE NAME:(sqlplus@node1 (TNS V1-V3))
2014
-07
-02
14
:
58
:
47.532
*** ACTION NAME:()
2014
-07
-02
14
:
58
:
47.532
KGH Latch Directory Information
ldir state:
2
last
allocated slot:
99
Slot [
1
] Latch:
0x200065ec
Index:
1
Flags:
3
State:
2
next: (nil)
Slot [
2
] Latch:
0x3e75571c
Index:
1
Flags:
3
State:
2
next: (nil)
......(省略）
Slot [
99
] Latch:
0x2002616c
Index:
1
Flags:
3
State:
2
next:
0x1
******************************************************
HEAP DUMP heap name=
"sga heap"
desc=
0x200010b4
extent sz=
0x7ad4
alt=
124
het=
32767
rec=
9
flg=
-126
opc=
0
parent=(nil) owner=(nil) nex=(nil) xsz=
0x0
heap=(nil)
fl2=
0x60
, nex=(nil)
ds
for
latch
1
:
0x2002a990
0x2002b5c8
0x2002c200
0x2002ce38
reserved granule count
0
(granule size
4194304
)
******************************************************
HEAP DUMP heap name=
"sga heap(1,0)"
desc=
0x2002a990
extent sz=
0xfc4
alt=
124
het=
32767
rec=
9
flg=
-126
opc=
0
parent=(nil) owner=(nil) nex=(nil) xsz=
0x400000
heap=(nil)
fl2=
0x20
, nex=(nil)
latch set
1
of
1
durations enabled
for
this
heap
reserved granules
for
root
0
(granule size
4194304
)
EXTENT
0
addr=
0x3b800000
Chunk 3b800038 sz=
24
R-freeable
"reserved stoppe"
Chunk 3b800050 sz=
212888
R-free
" "
Chunk 3b833fe8 sz=
24
R-freeable
"reserved stoppe"
Chunk 3b834000 sz=
3981312
perm
"perm "
alo=
3290272
EXTENT
1
addr=
0x3bc00000
Chunk 3bc00038 sz=
24
R-freeable
"reserved stoppe"
Chunk 3bc00050 sz=
212888
R-free
" "
Chunk 3bc33fe8 sz=
24
R-freeable
"reserved stoppe"
Chunk 3bc34000 sz=
3510272
perm
"perm "
alo=
3510272
Chunk 3bf8d000 sz=
465920
perm
"perm "
alo=
465920
Chunk 3bffec00 sz=
5120
free
" "
EXTENT
2
addr=
0x3c000000
Chunk 3c000038 sz=
24
R-freeable
"reserved stoppe"
Chunk 3c000050 sz=
212888
R-free
" "
Chunk 3c033fe8 sz=
24
R-freeable
"reserved stoppe"
Chunk 3c034000 sz=
3850176
perm
"perm "
alo=
3850176
Chunk 3c3dffc0 sz=
131088
perm
"perm "
alo=
131088
Chunk 3c3fffd0 sz=
48
free
" "
EXTENT
3
addr=
0x3c400000
Chunk 3c400038 sz=
24
R-freeable
"reserved stoppe"
Chunk 3c400050 sz=
212888
R-free
" "
Chunk 3c433fe8 sz=
24
R-freeable
"reserved stoppe"
Chunk 3c434000 sz=
3980368
perm
"perm "
alo=
3980368
Chunk 3c7ffc50 sz=
944
free
" "
EXTENT
4
addr=
0x3c800000
Chunk 3c800038 sz=
24
R-freeable
"reserved stoppe"
Chunk 3c800050 sz=
212888
R-free
" "
Chunk 3c833fe8 sz=
24
R-freeable
"reserved stoppe"
Chunk 3c834000 sz=
3672700
perm
"perm "
alo=
3672700
Chunk 3cbb4a7c sz=
308240
perm
"perm "
alo=
308240
Chunk 3cbffe8c sz=
372
free
" "
|
CHUNK
Chunk是以链条（chain）的方式存在于内存区，每个chunk包含header和body两部分，chunk的状态大体上可以分为free（可立即使用）、recreatable（可再生）、freeable（只有在session或call期间内保存必要的对象状态）、permanent（永久、不可再生）等，其中free和recreatable状态下的chunk可以重复使用。
FREE LIST
Free list主要用于管理空闲的chunk，并且是用bucket管理的。从Oracle 9i开始，一个heap总共255个bucket，bucket所包含的free chunk大小随bucket的编号增加而递增，个bucket下的free chunk已linked list的形式链接。
（1）获得shared pool latch在free list中查找合适大小的空闲chunk。如果在获取shared pool latch时发生了争用，则会出现latch：shared pool等待事件。这时Oracle会一直持有shared pool latch，直到获得所需的内存为止。所在内存碎片化比较严重的shared pool中，进程持有shared pool latch的时间也会相应变长。
（2）如果不存在合适大小的空闲chunk，则在查找到更大的空闲chunk后分割（split）使用，分割后剩下的内存区域则重新登记到free list中。分割内存意味着内存中的碎片开始增多。由于每个cursor所需内存的大小不同，所以shared pool的空闲内存不像buffer cache中的空闲内存一样具有固定大小。
（3）如果检索了free list也没有找到所有合适的空闲chunk，则检索lru list。lru list上的chunk是重建（recreatable）的，而且是当前不使用的（没有处于pin状态）。
（4）如果在lru list上也没有找到合适的chunk，且所请求的内存还没有达到隐含参数_shared_pool_reserved_min_alloc的阈值，则追加分配share pool中剩余的内存空间。
（5）如果以上请求的内存均失败，则出现ORA-4031错误
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|
FREE LISTS:
Bucket
0
size=
16
Bucket
1
size=
20
Bucket
2
size=
24
Bucket
3
size=
28
Bucket
4
size=
32
Bucket
5
size=
36
Bucket
6
size=
40
Bucket
7
size=
44
Bucket
8
size=
48
Chunk 3c3fffd0 sz=
48
free
" "
Chunk 3ebfffd0 sz=
48
free
" "
Bucket
9
size=
52
Bucket
10
size=
56
Bucket
11
size=
60
Bucket
12
size=
64
Bucket
13
size=
68
Bucket
14
size=
72
Bucket
15
size=
76
Bucket
16
size=
80
Bucket
17
size=
84
Bucket
18
size=
88
Chunk 3e7fffa8 sz=
88
free
" "
Bucket
19
size=
92
Bucket
20
size=
96
Bucket
21
size=
100
Bucket
22
size=
104
Bucket
23
size=
108
Bucket
24
size=
112
Bucket
25
size=
116
Bucket
26
size=
120
Bucket
27
size=
124
......
|
LRU LIST
Lru list主要保存着当前未使用而且可以重建的chunk。当会话在free list中找不到空闲的chunk时，在会在lru list中寻找。
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23
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26
27
28
29
30
31
32
|
UNPINNED RECREATABLE CHUNKS (lru
first
):
Chunk 3b1f4000 sz=
4096
recreate
"CCUR^3de2d7f5 "
latch=(nil)
Chunk 3a649000 sz=
4096
recreate
"CCUR^f5a8106a "
latch=(nil)
Chunk 383b3000 sz=
4096
recreate
"CCUR^2b855a04 "
latch=(nil)
Chunk 383b1000 sz=
4096
recreate
"CCUR^f65cc3ed "
latch=(nil)
Chunk 3ee4c524 sz=
332
recreate
"KGLHD "
latch=(nil)
Chunk 3af76da8 sz=
4096
recreate
"SQLA^13df1501 "
latch=(nil)
Chunk 3a72e000 sz=
4096
recreate
"CCUR^13df1501 "
latch=(nil)
Chunk 39ff96e0 sz=
332
recreate
"KGLHD "
latch=(nil)
Chunk 3a37e740 sz=
4096
recreate
"SQLA^7a9f4a60 "
latch=(nil)
Chunk
38330000
sz=
4096
recreate
"CCUR^7a9f4a60 "
latch=(nil)
Chunk 39f8732c sz=
332
recreate
"KGLHD "
latch=(nil)
Chunk 3ab0dec4 sz=
4096
recreate
"SQLA^8005cf3c "
latch=(nil)
Chunk 3a670000 sz=
4096
recreate
"CCUR^8005cf3c "
latch=(nil)
Chunk 3ed28b1c sz=
1524
recreate
"KGLHD "
latch=(nil)
Chunk 39cb0d20 sz=
332
recreate
"KGLHD "
latch=(nil)
Chunk 3aaeb214 sz=
4096
recreate
"SQLA^63c15ff "
latch=(nil)
Chunk 3a646000 sz=
4096
recreate
"CCUR^63c15ff "
latch=(nil)
Chunk 39ff9a38 sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 3ee4c88c sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 3ee4caa8 sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 39fabd2c sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 39fabf48 sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 3ee481f8 sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 3ee48414 sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 3ee48630 sz=
540
recreate
"KQR PO "
latch=
0x3ca28438
Chunk 3a1a1228 sz=
4096
recreate
"KGLS^9b4819a8 "
latch=(nil)
Chunk 39b4a504 sz=
4096
recreate
"KGLS^6ccccfe "
latch=(nil)
Chunk 3abf0fb4 sz=
4096
recreate
"KGLS^8db54da "
latch=(nil)
Chunk 3aa65508 sz=
4096
recreate
"KGLS^e2d7481e "
latch=(nil)
Chunk 3a2839d0 sz=
4096
recreate
"KGLS^8dd845ff "
latch=(nil)
Chunk 3abd4f78 sz=
4096
recreate
"KGLS^f79d229a "
latch=(nil)
|
RESERVED FREE LIST
Oracle 设置了保留内存区域，该区域用 Reserved free list管理。其大小由参数shared_pool_reserved_size决定（最小为5000字节，最大不能超过shared pool的50%）。
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35
|
RESERVED FREE LISTS:
Reserved bucket
0
size=
16
Chunk 3dfffc14 sz=
980
R-free
" "
Chunk 3dbffbe0 sz=
1032
R-free
" "
Reserved bucket
1
size=
4400
Reserved bucket
2
size=
8204
Reserved bucket
3
size=
8460
Reserved bucket
4
size=
8464
Reserved bucket
5
size=
8468
Reserved bucket
6
size=
8472
Reserved bucket
7
size=
9296
Reserved bucket
8
size=
9300
Reserved bucket
9
size=
12320
Reserved bucket
10
size=
12324
Reserved bucket
11
size=
16396
Reserved bucket
12
size=
32780
Reserved bucket
13
size=
65548
Chunk 3b800050 sz=
212888
R-free
" "
Chunk 3bc00050 sz=
212888
R-free
" "
Chunk 3c000050 sz=
212888
R-free
" "
Chunk 3c400050 sz=
212888
R-free
" "
Chunk 3c800050 sz=
212888
R-free
" "
Chunk 3cc00050 sz=
212888
R-free
" "
Chunk 3d3cb8b8 sz=
214832
R-free
" "
Chunk 3d400050 sz=
212888
R-free
" "
Chunk
3e000050
sz=
212888
R-free
" "
Chunk
3e400050
sz=
212888
R-free
" "
Chunk
3e800050
sz=
212888
R-free
" "
Chunk 3f000050 sz=
212888
R-free
" "
Reserved bucket
14
size=
1990630
Total reserved free space =
2558612
UNPINNED RECREATABLE CHUNKS (lru
first
):
Chunk 3b1f4000 sz=
4096
recreate
"CCUR^3de2d7f5 "
latch=(nil)
Chunk 3a649000 sz=
4096
recreate
"CCUR^f5a8106a "
latch=(nil)
......
|
Oracle对进入reserved free list的对象大小有限制，即只有大于_shared_pool_reserved_min_alloc隐含参数阈值（默认值4400）的cursor才能进入到reserved free list。
SHARED POOL的SUB POOL技术
从Oracle 9i开始，shared pool可以分为多个sub pool，其数量受一下几个因素影响：
1、系统的CPU数量，默认情况下，在Oracle中每4个CPU分配一个sub pool，最多不能超过7个。
2、共享池的大小。sub pool的最小容量随着Oracle版本不同而不同。
9i ----- 128M（Minimum subpool size）
10g<10.2.0.3 ---- 256M
10.2.0.3 and higher ---512M
3、隐含参数_kghdisdx_count值
每个sub pool拥有独立的free list 、lru list和shared pool latch。从这个角度来讲，当系统拥有足够的内存和CPU时，将shared pool分为多个sub pool时能有效的减少shared pool latch的争用。
查看sub pool的数量：
|
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|
kghlushrpool： =
1
: shared pool subpools =
0
: java pool
SQL> select count(kghluidx) num_pools
2
from
x$kghlu
3
where
kghlushrpool=
1
4
/
NUM_POOLS
----------
1
SQL> show parameter cpu
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
cpu_count integer
1
|
查看sub pool latch信息：
|
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|
SQL> col name
for
a40
SQL> set linesize
120
SQL> r
1
select addr,name,gets,misses,spin_gets
2
from
v$latch_children
3
*
where
name =
'shared pool'
ADDR NAME GETS MISSES SPIN_GETS
-------- ---------------------------------------- ---------- ---------- ----------
200A80FC shared pool
21
0
0
200A8098 shared pool
21
0
0
200A8034 shared pool
21
0
0
200A7FD0 shared pool
21
0
0
200A7F6C shared pool
21
0
0
200A7F08 shared pool
21
0
0
200A7EA4 shared pool
493378
7
0
7
rows selected.
|
查看sub pool 内存分配：
X$KSMSS([K]ernal [S]torage [M]emory Management [S]GA [S]atistics (lengths of SGA objects)
|
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|
SQL> select
2
'shared pool('
|| nvl(decode(to_char(ksmdsidx),
'0'
,
'0-unused'
,ksmdsidx),
'Total'
)
3
||
'):'
subpool,
4
sum(ksmsslen) bytes,round(sum (ksmsslen)/
1048576
,
2
) mb
5
from
x$ksmss
6
where
ksmsslen >
0
7
group by rollup (ksmdsidx) order by subpool asc;
SUBPOOL BYTES MB
------------------------------------------------------ ---------- ----------
shared pool(
1
):
121639892
116
shared pool(Total):
121639892
116
|
SQL>
Oracle 硬解析
1、获得shared pool latch ，从free list的bucket 中查找合适大小的free chunk。如果free list中的bucket list过长或者shared pool碎片化严重，那么在多个进程同时请求分配内存时，则会发生shared pool latch的争用。
2、如果不存在大小合适的free chunk，则分割较大的free chunk，分割后的free chunk重新挂载到适当大小的bucket下。如果不存在free chunk，则检索lru list。若在lru list中也不能获得合适大小的bucket，则从shared pool的剩余空闲内存中分配。如果cursor大小大于_shared_pool_reserved_min_alloc隐含参数设定的阀值，那么在reserved list中寻找free chunk。若果以上过程均失败，则出现ORA-4031错误。
3、若找到合适大小的chunk，则对cursor相应的handle（library cache handle）以exclusive 模式获得library cache lock，并创建LCO信息。在创建LCO信息后，library cache lock变换为null模式，然后以exclusive模式获得library cache pin，并创建执行计划等信息。硬解析成功后Oracle增加parse count（hard）统计值。
4、对sql cursor已shared模式获得library cache lock和library cache pin，并执行sql，这个阶段称之为执行阶段。
5、sql cursor执行结束后进入fetch阶段。在fetch阶段，sql cursor将library cache pin变为null模式，并释放library cache pin。
软软解析
由于在软解析过程中需要获得library cache latch，所以在高并发软解析的系统中，依然会出现与latch：library cache相关的等待事件，从而导致性能缓慢。
软软解析（Tom Kety）核心原理是通过设置session_cache_cursors参数将某个会话中常用的sql放入UGA的会话缓存区中，当会话发起相同的sql时，可以快速的从UGA取得cursor的信息，从而减少共享池的争用。当一个cursor被解析3次以上（包括3次）就会被放入到UG会话缓存区中。
案例：shared pool latch 争用
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127
|
案例
1
：
业务运行前：
17
:
07
:
30
SYS@ prod>select name,GETS,MISSES
from
v$latch
where
upper(name) like
'%LIBRARY%'
OR upper(name) like
'%SHARE%'
;
NAME GETS MISSES
---------------------------------------------------------------- ---------- ----------
test shared non-parent l0
0
0
ksxp shared latch
0
0
kcfis stats shared latch
0
0
shared pool
126676
61
library cache load lock
0
0
shared pool simulator
6576
0
shared pool sim alloc
45
0
Shared B-Tree
302
0
shared server configuration
6
0
shared server info
1
0
运行业务：
17
:
08
:
34
SCOTT@ prod>begin
17
:
08
:
38
2
for
i
in
1.
.100000
loop
17
:
08
:
52
3
execute immediate
'insert into t1 values ('
||i||
')'
;
17
:
09
:
18
4
end loop;
17
:
09
:
26
5
end;
17
:
09
:
27
6
/
PL/SQL procedure successfully completed.
业务运行后：
17
:
11
:
05
SYS@ prod>select name,GETS,MISSES
from
v$latch
where
upper(name) like
'%LIBRARY%'
OR upper(name) like
'%SHARE%'
NAME GETS MISSES
---------------------------------------------------------------- ---------- ----------
test shared non-parent l0
0
0
ksxp shared latch
0
0
kcfis stats shared latch
0
0
shared pool
4526672
214
library cache load lock
0
0
shared pool simulator
1086437
0
shared pool sim alloc
2048
0
Shared B-Tree
316
0
shared server configuration
6
0
shared server info
1
0
10
rows selected.
17
:
15
:
42
SYS@ prod>select sid,event,WAIT_TIME,state
from
v$session_wait
where
sid=
42
SID EVENT WAIT_TIME STATE
---------- ---------------------------------------------------------------- ---------- -------------------
42
latch: shared pool
-1
WAITED SHORT TIME
Elapsed:
00
:
00
:
00.08
案例
2
：
业务运行前：
17
:
18
:
35
SYS@ prod>select sid,EVENT,TOTAL_WAITS,AVERAGE_WAIT
from
v$session_event
where
sid
in
(
42
,
46
);
SID EVENT TOTAL_WAITS AVERAGE_WAIT
---------- ---------------------------------------------------------------- ----------- ------------
42
Disk file operations I/O
4
.03
42
log file switch (
private
strand flush incomplete)
1
10.03
42
log file sync
4
1.76
42
db file sequential read
385
.23
42
latch: row cache objects
5
.44
42
latch: shared pool
194
.25
42
SQL*Net message to client
24
0
42
SQL*Net message
from
client
23
5318.9
42
SQL*Net
break
/reset to client
2
.08
42
events
in
waitclass Other
1
0
46
Disk file operations I/O
1
.03
46
db file sequential read
33
.02
46
SQL*Net message to client
13
0
46
SQL*Net message
from
client
12
79.9
14
rows selected.
运行业务：
17
:
16
:
39
SYS@ prod>select sid ,username
from
v$session
where
username is
not
null
;
SID USERNAME
---------- ------------------------------
1
SYS
42
SCOTT
46
HR
17
:
17
:
22
SCOTT@ prod>begin
17
:
20
:
46
2
for
i
in
1.
.100000
loop
17
:
20
:
52
3
execute immediate
'insert into t1 values ('
||i||
')'
;
17
:
20
:
58
4
end loop;
17
:
21
:
02
5
end;
17
:
21
:
05
6
/
PL/SQL procedure successfully completed.
17
:
17
:
42
HR@ prod>begin
17
:
21
:
16
2
for
i
in
1.
.100000
loop
17
:
21
:
24
3
execute immediate
'insert into scott.t1 values ('
||i||
')'
;
17
:
21
:
49
4
end loop;
17
:
21
:
51
5
end;
17
:
21
:
52
6
/
PL/SQL procedure successfully completed.
业务运行后：
17
:
22
:
32
SYS@ prod>select sid,EVENT,TOTAL_WAITS,AVERAGE_WAIT
from
v$session_event
where
sid
in
(
42
,
46
);
SID EVENT TOTAL_WAITS AVERAGE_WAIT
---------- ---------------------------------------------------------------- ----------- ------------
42
Disk file operations I/O
4
.03
42
latch: cache buffers chains
16
.18
42
buffer busy waits
2
.15
42
log file switch (
private
strand flush incomplete)
1
10.03
42
log file sync
4
1.76
42
db file sequential read
413
.21
42
latch: row cache objects
58
.13
42
latch: shared pool
1008
.19
42
library cache: mutex X
123
.33
42
SQL*Net message to client
24
0
42
SQL*Net message
from
client
24
6044.43
42
SQL*Net
break
/reset to client
2
.08
42
events
in
waitclass Other
87
.09
46
Disk file operations I/O
3
.03
46
latch: cache buffers chains
13
.21
46
buffer busy waits
1
.35
46
latch: redo copy
1
1.26
SID EVENT TOTAL_WAITS AVERAGE_WAIT
---------- ---------------------------------------------------------------- ----------- ------------
46
db file sequential read
38
.02
46
enq: HW - contention
1
.01
46
latch: row cache objects
58
.14
46
row cache lock
1
.08
46
latch: shared pool
666
.17
46
library cache: mutex X
99
.29
46
SQL*Net message to client
13
0
46
SQL*Net message
from
client
13
2010.63
46
events
in
waitclass Other
68
.14
26
rows selected.
Elapsed:
00
:
00
:
00.37
17
:
22
:
42
SYS@ prod>
17
:
22
:
02
SYS@ prod>select sid,event,WAIT_TIME,state
from
v$session_wait
where
sid=
42
17
:
22
:
25
2
or
sid=
46
;
SID EVENT WAIT_TIME STATE
---------- ---------------------------------------------------------------- ---------- -------------------
42
latch: shared pool
-1
WAITED SHORT TIME
46
latch: shared pool
-1
WAITED SHORT TIME
|
本文转自 客居天涯 51CTO博客，原文链接：http://blog.51cto.com/tiany/1433452，如需转载请自行联系原作者
