wait for a undo record

今天在做AWR分析时，碰到了个新的等待事件：wait for a undo recordITPUB个人空间&J B2q-Ya^1v*_

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T)T-B2hN0Top 5 Timed Events Avg %TotalITPUB个人空间 A I _E"bZO
~~~~~~~~~~~~~~~~~~ wait Call
'f&j3]I)y0Event Waits Time (s) (ms) Time Wait ClassITPUB个人空间%~{,T-_*GtG
------------------------------ ------------ ----------- ------ ------ ----------

UF,M9a]9S0wait for a undo record 54,998 3,557 65 43.0 Other
0G:[ E%kp n-Ly0CPU time 1,687 20.4ITPUB个人空间4az ?*Z
_
db file sequential read 187,848 1,632 9 19.7 User I/OITPUB个人空间w"[;l4xg[1f
wait for stopper event to be i 4,027 278 69 3.4 Other
l dIw&tYm#x/o.e0read by other session 47,621 276 6 3.3 User I/OITPUB个人空间 s/C7g;r4}7]d
-------------------------------------------------------------
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]{c'GQz0查看了下当前数据库的等待事件，有大量的的Txn Recovery Start，ITPUB个人空间7s9nOT(LO-N!^EV!o
看样子是kill的大事务，数据库正在恢复ITPUB个人空间TTx6P9PL
ITPUB个人空间;XH'EO K:h
SQL> select sid, event, wait_class from v$session_wait s where s.EVENT not in ('SQL*Net message from client', 'rdbms ipc message');ITPUB个人空间O+s? B+Cc

&v6Sz(\v6q#R#~ K0SID EVENT WAIT_CLASS
o1G:y$h _:i0x-R.H2e j0---- ---------------------------------------------------------------- ----------------------------------------------------------------ITPUB个人空间BB!_~2NP
2070 PX Deq: Txn Recovery Start IdleITPUB个人空间Qd J0UGXS W L
2114 PX Deq: Txn Recovery Start Idle
!nP/D{PmV/n02168 PX Deq: Txn Recovery Start Idle
Ln
bs;q ?1HB02239 SQL*Net message to client NetworkITPUB个人空间xWI%R(C Po'r
2249 PX Deq: Txn Recovery Start Idle
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s'cSH3AH02264 jobq slave wait Idle
X xYGh u-Dx02283 wait for a undo record Other
s wIk)h at7e02306 PX Deq: Txn Recovery Start IdleITPUB个人空间7PsvT*CAn
2383 jobq slave wait IdleITPUB个人空间s i ge6mr3h7w
2414 PX Deq: Txn Recovery Start IdleITPUB个人空间1?:w2`]mTp
2455 PX Deq: Txn Recovery Start IdleITPUB个人空间j4A/Kh;h @"W*v(d7E$y2z
2474 jobq slave wait IdleITPUB个人空间r&k @L3Yq m_a
2475 db file sequential read User I/O
}p.Nv6j*l-\9WA02492 jobq slave wait IdleITPUB个人空间%RA`$b3ek,Z)w
2499 PX Deq: Txn Recovery Start Idle
7c7O:e,Nvt02512 PX Deq: Txn Recovery Start Idle
/X }/e5k4f02550 PX Deq: Txn Recovery Start Idle
e{$R9H Y J)D02556 PX Deq: Txn Recovery Start IdleITPUB个人空间nsqL,mV0k9Z
2591 PX Deq: Txn Recovery Start IdleITPUB个人空间
T~nK!iV9s
2629 PX Deq: Txn Recovery Start IdleITPUB个人空间 r7Y }4r:m7Asi
2664 PX Deq: Txn Recovery Start IdleITPUB个人空间#Y#f kv~;Y*g1mb
2700 db file sequential read User I/OITPUB个人空间
}Y hH
Z;D~q
2712 PX Deq: Txn Recovery Start Idle
x}(].kp02726 jobq slave wait Idle
_~%Ki)~$\&d02727 Streams AQ: waiting for time management or cleanup tasks IdleITPUB个人空间*US/D&V*G&K,v(R)_ | c
2735 Streams AQ: qmn coordinator idle wait IdleITPUB个人空间s }3Dz p+`2ZOJ
2736 Streams AQ: qmn slave idle wait Idle
9W)hh F,O n6IXb02738 jobq slave wait IdleITPUB个人空间G$wbgs1w.K;gF
2748 wait for stopper event to be increased OtherITPUB个人空间 WP+W"f6Q f5U
ITPUB个人空间 ~:W!E:b B
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29 rows selectedITPUB个人空间
C&hZ9eq$}w

)BDi,O Cy)pAu0查看v$fast_start_servers：
en:aV^h0ITPUB个人空间0Fb` ?'[ N |,jX%f({
SQL> select pid, state, undoblocksdone from v$fast_start_servers;ITPUB个人空间A,t(q#mp5F!w0Qs

.?TQ)u f0}k4u0 PID STATE UNDOBLOCKSDONEITPUB个人空间8^;HVM7q\
---------- ----------- --------------
p/\wXJ1o$J+W0 157 RECOVERING 3123ITPUB个人空间rw/W3`+T ^#o
322 RECOVERING 0
:O1I f5CSg0 335 RECOVERING 0
&^%Y'U`p-H O|0 455 RECOVERING 0ITPUB个人空间9u0p/gDQ0rv\m
458 RECOVERING 0ITPUB个人空间8s9Cr,TT^ W@HL[
460 RECOVERING 0ITPUB个人空间!t:hu.HI+~5ak!H
461 RECOVERING 0
^i
[ur
q C$OA QA0 463 RECOVERING 0
&Q'o/DJ4o.CTN7G0 467 RECOVERING 0
sH9a$C:O0 468 RECOVERING 0
K'hW/P!VCf'q+Jm0 471 RECOVERING 0
yz.bUU_0 472 RECOVERING 0ITPUB个人空间Ln%C2`!d/z%f jrb
477 RECOVERING 0
jkyl'N?)E2U0 480 RECOVERING 0ITPUB个人空间:n g0F1Z T'w9`(jJ2`
481 RECOVERING 0ITPUB个人空间'Q'zE3{#R7?
484 RECOVERING 0
1TD/lU,ee CG l0ITPUB个人空间*B4JdH)g CY
16 rows selectedITPUB个人空间:I&hn(Q,Y b;p2I

;gs&ojtb"R$@0SQL> select pid, state, undoblocksdone from v$fast_start_servers;ITPUB个人空间$us u}2M Kb8k

y6A r-g$`,gA0 PID STATE UNDOBLOCKSDONE
)hn2J.V@6qGib]ip0---------- ----------- --------------
v"T,i Nd#z I0 157 RECOVERING 3458
]'RR-~G0 322 RECOVERING 0ITPUB个人空间
Oz$P3Ec
335 RECOVERING 0
y M1|+CUx8Cmj
kkU0 455 RECOVERING 0ITPUB个人空间 M;TC
VkG5h
458 RECOVERING 0ITPUB个人空间i(DVw y/uwu
460 RECOVERING 0
4oT
\X(b r S4U0 461 RECOVERING 0
_+}Or
_\0 463 RECOVERING 0ITPUB个人空间"\/V-k-{'C#^]4o5}
467 RECOVERING 0
@$G%\d MR0 468 RECOVERING 0ITPUB个人空间k^CT
J2y7Fm
471 RECOVERING 0
3KB4} Fh c_0 472 RECOVERING 0ITPUB个人空间U1c)iLcA#A!A]6O5r
477 RECOVERING 0ITPUB个人空间h J }
oRL;r[
480 RECOVERING 0ITPUB个人空间d2} [P \{
481 RECOVERING 0ITPUB个人空间,\ Kd2k&c)z
484 RECOVERING 0
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'k:S}
O6MdE_MZ016 rows selectedITPUB个人空间w:ON4G\F
ITPUB个人空间 H]$V?EK;II D

6|W-EB X6{{:ef*O0当数据库恢复结束，wait for a undo record等待事件消失