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小編給大家分享一下Oracle Share Pool內(nèi)部管理機(jī)制的示例分析，希望大家閱讀完這篇文章之后都有所收獲，下面讓我們一起去探討吧！
Oracle Share Pool內(nèi)部管理機(jī)制
SHARE POOL利用堆（HEAP)的內(nèi)存管理方式管理，在物理上由多個內(nèi)存區(qū)（EXTENT)組成，內(nèi)存區(qū)又由多個不同大小的CHUNK組成。而CHUNK又有可重用和空閑之分，并且它們分別有LRU LIST、FREE LIST、RESERVED LIST串聯(lián)起來。
堆管理
Shared Pool是利用堆內(nèi)存管理方式管理的（KGH:Kernel Generic Heap).從Oracle 9i開始，可以有多個最高級堆（TOP-LEVLE HEAP)，最高級堆可以分成多個副堆，副堆下面還擁有子堆。堆和副對結(jié)構(gòu)基本相同。從物理上講，一個堆由多個內(nèi)存區(qū)已link list的形式連接組成。一個內(nèi)存區(qū)物理上使用一個Granule，一個內(nèi)存區(qū)由多個chunk組成，所以chunk是heap的最小內(nèi)存單位。
Chunk的使用情況可由X$KSMSP內(nèi)部視圖查看。每個堆頭上則包含了可使用的chunk列表和已使用的chunk列表。通過dump heap命令可以在trace文件中觀察heap和extent的關(guān)系。
alter system set events 'immediate trace name heapdump level 2';
案例：
SQL> select name,bytes/1024/1024 from v$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, p_w_picpath: 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是以鏈條（chain）的方式存在于內(nèi)存區(qū)，每個chunk包含header和body兩部分，chunk的狀態(tài)大體上可以分為free（可立即使用）、recreatable（可再生）、freeable（只有在session或call期間內(nèi)保存必要的對象狀態(tài)）、permanent（永久、不可再生）等，其中free和recreatable狀態(tài)下的chunk可以重復(fù)使用。
FREE LIST
Free list主要用于管理空閑的chunk，并且是用bucket管理的。從Oracle 9i開始，一個heap總共255個bucket，bucket所包含的free chunk大小隨bucket的編號增加而遞增，個bucket下的free chunk已linked list的形式鏈接。
（1）獲得shared pool latch在free list中查找合適大小的空閑chunk。如果在獲取shared pool latch時發(fā)生了爭用，則會出現(xiàn)latch：shared pool等待事件。這時Oracle會一直持有shared pool latch，直到獲得所需的內(nèi)存為止。所在內(nèi)存碎片化比較嚴(yán)重的shared pool中，進(jìn)程持有shared pool latch的時間也會相應(yīng)變長。
（2）如果不存在合適大小的空閑chunk，則在查找到更大的空閑chunk后分割（split）使用，分割后剩下的內(nèi)存區(qū)域則重新登記到free list中。分割內(nèi)存意味著內(nèi)存中的碎片開始增多。由于每個cursor所需內(nèi)存的大小不同，所以shared pool的空閑內(nèi)存不像buffer cache中的空閑內(nèi)存一樣具有固定大小。
（3）如果檢索了free list也沒有找到所有合適的空閑chunk，則檢索lru list。lru list上的chunk是重建（recreatable）的，而且是當(dāng)前不使用的（沒有處于pin狀態(tài)）。
（4）如果在lru list上也沒有找到合適的chunk，且所請求的內(nèi)存還沒有達(dá)到隱含參數(shù)_shared_pool_reserved_min_alloc的閾值，則追加分配share pool中剩余的內(nèi)存空間。
（5）如果以上請求的內(nèi)存均失敗，則出現(xiàn)ORA-4031錯誤
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主要保存著當(dāng)前未使用而且可以重建的chunk。當(dāng)會話在free list中找不到空閑的chunk時，在會在lru list中尋找。
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 設(shè)置了保留內(nèi)存區(qū)域，該區(qū)域用 Reserved free list管理。其大小由參數(shù)shared_pool_reserved_size決定（最小為5000字節(jié)，最大不能超過shared pool的50%）。
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對進(jìn)入reserved free list的對象大小有限制，即只有大于_shared_pool_reserved_min_alloc隱含參數(shù)閾值（默認(rèn)值4400）的cursor才能進(jìn)入到reserved free list。
SHARED POOL的SUB POOL技術(shù)
從Oracle 9i開始，shared pool可以分為多個sub pool，其數(shù)量受一下幾個因素影響：
1、系統(tǒng)的CPU數(shù)量，默認(rèn)情況下，在Oracle中每4個CPU分配一個sub pool，最多不能超過7個。
2、共享池的大小。sub pool的最小容量隨著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、隱含參數(shù)_kghdisdx_count值
每個sub pool擁有獨(dú)立的free list 、lru list和shared pool latch。從這個角度來講，當(dāng)系統(tǒng)擁有足夠的內(nèi)存和CPU時，將shared pool分為多個sub pool時能有效的減少shared pool latch的爭用。
查看sub pool的數(shù)量：
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：
SQL> col name for a40 SQL> set linesize 120 SQL> r 1 select addr,name,gets,misses,spin_gets 2 from v$latch_children 3* where name ='shared pool' ADDR NAME GETS MISSES SPIN_GETS -------- ---------------------------------------- ---------- ---------- ---------- 200A80FC shared pool 21 0 0 200A8098 shared pool 21 0 0 200A8034 shared pool 21 0 0 200A7FD0 shared pool 21 0 0 200A7F6C shared pool 21 0 0 200A7F08 shared pool 21 0 0 200A7EA4 shared pool 493378 7 0 7 rows selected.
查看sub pool 內(nèi)存分配：
X$KSMSS([K]ernal [S]torage [M]emory Management [S]GA [S]atistics (lengths of SGA objects)
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$ksmss
6 where ksmsslen >0
7 group by rollup (ksmdsidx) order by subpool asc;
SUBPOOL BYTES MB
------------------------------------------------------ ---------- ----------
shared pool(1): 121639892 116
shared pool(Total): 121639892 116SQL>
Oracle 硬解析
1、獲得shared pool latch ，從free list的bucket 中查找合適大小的free chunk。如果free list中的bucket list過長或者shared pool碎片化嚴(yán)重，那么在多個進(jìn)程同時請求分配內(nèi)存時，則會發(fā)生shared pool latch的爭用。
2、如果不存在大小合適的free chunk，則分割較大的free chunk，分割后的free chunk重新掛載到適當(dāng)大小的bucket下。如果不存在free chunk，則檢索lru list。若在lru list中也不能獲得合適大小的bucket，則從shared pool的剩余空閑內(nèi)存中分配。如果cursor大小大于_shared_pool_reserved_min_alloc隱含參數(shù)設(shè)定的閥值，那么在reserved list中尋找free chunk。若果以上過程均失敗，則出現(xiàn)ORA-4031錯誤。
3、若找到合適大小的chunk，則對cursor相應(yīng)的handle（library cache handle）以exclusive 模式獲得library cache lock，并創(chuàng)建LCO信息。在創(chuàng)建LCO信息后，library cache lock變換為null模式，然后以exclusive模式獲得library cache pin，并創(chuàng)建執(zhí)行計劃等信息。硬解析成功后Oracle增加parse count（hard）統(tǒng)計值。
4、對sql cursor已shared模式獲得library cache lock和library cache pin，并執(zhí)行sql，這個階段稱之為執(zhí)行階段。
5、sql cursor執(zhí)行結(jié)束后進(jìn)入fetch階段。在fetch階段，sql cursor將library cache pin變?yōu)閚ull模式，并釋放library cache pin。
軟軟解析
由于在軟解析過程中需要獲得library cache latch，所以在高并發(fā)軟解析的系統(tǒng)中，依然會出現(xiàn)與latch：library cache相關(guān)的等待事件，從而導(dǎo)致性能緩慢。
軟軟解析（Tom Kety）核心原理是通過設(shè)置session_cache_cursors參數(shù)將某個會話中常用的sql放入UGA的會話緩存區(qū)中，當(dāng)會話發(fā)起相同的sql時，可以快速的從UGA取得cursor的信息，從而減少共享池的爭用。當(dāng)一個cursor被解析3次以上（包括3次）就會被放入到UG會話緩存區(qū)中。
案例：shared pool latch 爭用
案例1：
業(yè)務(wù)運(yùn)行前：
17:07:30 SYS@ prod>select name,GETS,MISSES from v$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
運(yùn)行業(yè)務(wù)：
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.
業(yè)務(wù)運(yùn)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：
業(yè)務(wù)運(yùn)行前：
17:18:35 SYS@ prod>select sid,EVENT,TOTAL_WAITS,AVERAGE_WAIT from v$session_event where sid in (42,46);
SID EVENT TOTAL_WAITS AVERAGE_WAIT
---------- ---------------------------------------------------------------- ----------- ------------
42 Disk file operations I/O 4 .03
42 log file switch (private strand flush incomplete) 1 10.03
42 log file sync 4 1.76
42 db file sequential read 385 .23
42 latch: row cache objects 5 .44
42 latch: shared pool 194 .25
42 SQL*Net message to client 24 0
42 SQL*Net message from client 23 5318.9
42 SQL*Net break/reset to client 2 .08
42 events in waitclass Other 1 0
46 Disk file operations I/O 1 .03
46 db file sequential read 33 .02
46 SQL*Net message to client 13 0
46 SQL*Net message from client 12 79.9
14 rows selected.
運(yùn)行業(yè)務(wù)：
17:16:39 SYS@ prod>select sid ,username from v$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.
業(yè)務(wù)運(yùn)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看完了這篇文章，相信你對“Oracle Share Pool內(nèi)部管理機(jī)制的示例分析”有了一定的了解，如果想了解更多相關(guān)知識，歡迎關(guān)注億速云行業(yè)資訊頻道，感謝各位的閱讀！
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