ENQUEUE TYPE ORACLE
EQ_NAME EQ_TYPE REQ_REASON REQ_DESCRIPTION
-------------------- -------------------- -------------------- --------------------
WLM Plan Operations WM WLM Plan activation Synchronizes new WLM
Plan activation
Cross-Instance Call CI contention Coordinates cross-in
Invocation stance function invo
cations
Process Startup PR contention Synchronizes process
startup
Planned Draining RAC DE Update Draining Test contention
enqueue
Parameter PE contention Synchronizes system
parameter updates
Global Parameter PG contention Synchronizes global
system parameter upd
ates
File Object FP global fob contentio Synchronizes various
n File Object(FOB) op
erations
Block Repair/Resilve RE block repair content Synchronize block re
ring ion pair/resilvering ope
rations
clonedb bitmap file BM clonedb bitmap file synchronizes clonedb
access write bitmap file operati
ons
Oracle File System O FO file system operatio Synchronizes various
peration n contention Oracle File system
operations
Scheduler KM contention Synchronizes various
Resource Manager op
erations
Scheduler Plan KT contention Synchronizes accesse
s to the current Res
ource Manager plan
Calibration CA contention Synchronizes various
IO calibration runs
Scheduler Master DBR KD determine DBRM maste Determine DBRM maste
M r r
KSV slave startup PV syncstart Synchronizes slave s
tart_shutdown
KSV slave startup PV syncshut Synchronizes instanc
e shutdown_slvstart
Spare Enqueue 0 SP contention 1 (1) due to one-off p
atch
Spare Enqueue 0 SP contention 2 (2) due to one-off p
atch
Spare Enqueue 0 SP contention 3 (3) due to one-off p
atch
Spare Enqueue 0 SP contention 4 (4) due to one-off p
atch
Spare Enqueue 1 SX contention 5 (5) due to one-off p
atch
Spare Enqueue 1 SX contention 6 (6) due to one-off p
atch
File Mapping FM contention Synchronizes access
to global file mappi
ng state
Internal Test XY contention Lock used for intern
al testing
Service Operations AS service activation Synchronizes new ser
vice activation
Property Lock PD contention Prevents others from
updating the same p
roperty
Rolling Migration RU contention Serializes rolling m
igration operations
Rolling Migration RU waiting Results of rolling m
igration CIC
ksz synch MX sync storage server Lock held to generat
info e a response to the
storage server infor
mation request when
an instance is start
ing up
read_write_snapshot WN rw snapshot synchron Synchronizes snapsho
ization t file creation
repopulation file ac ZX repopulation file wr synchronizes file op
cess ite erations during repo
pulation
Kernel Service ACL KA ACL control status Get ACL control stat
us lock
Reader Farm SQL Isol RI Reader Farm SQL Isol Reader Farm
ation ation
KJCI Serialization E KI contention Synchronizes Cross-I
nqueue nstance Calls
Application Continui AC acquiring partition Synchronizes partiti
ty id on id
Controlfile Transact CF contention Synchronizes accesse
ion s to the controlfile
Suspend Writes SW contention Coordinates the 'alt
er system suspend' o
peration
Database Suspend DS contention Prevents a database
suspend during LMON
reconfiguration
Tablespace Checkpoin TC contention Lock held to guarant
t ee uniqueness of a t
ablespace checkpoint
Tablespace Checkpoin TC contention2 Lock of setup of a u
t nqiue tablespace che
ckpoint in null mode
Buffer Cache PreWarm PW perwarm status in db DBWR 0 holds enqueue
w0 indicating prewarme
d buffers present in
cache
Buffer Cache PreWarm PW flush prewarm buffer Direct Load needs to
s flush prewarmed buf
fers if DBWR 0 holds
enqueue
Multiple Object Reus RO contention Coordinates flushing
e of multiple objects
Multiple Object Reus RO fast object reuse Coordinates fast obj
e ect reuse
Multiple Object Chec KO fast object checkpoi Coordinates fast obj
kpoint nt ect checkpoint
Reuse Block Range CR block range reuse ck Coordinates fast blo
pt ck range reuse ckpt
Tablespace Rekey TR serialize TS rekeys Performing online ta
blespace rekey
Tablespace Rekey TR database key open ch Database encryption
eck key open check
Tablespace Rekey TR serialize system rek Performing online ta
eys blespace rekey with
db key
Buddy Instance Conte BU recovery set constru RMS0 constructing rc
xt ct overy set
Buddy Instance Conte BU recovery set takeove instance recovery ta
xt r king-over recovery s
et
Being Written Redo L WL Test access/locking Testing redo transpo
og rt access/locking
Being Written Redo L WL RAC-wide SGA initial krsh_rsga_initialize
og ize access to RAC-wide
SGA
Being Written Redo L WL RAC-wide SGA write krsh_rsga_write acce
og ss to RAC-wide SGA
Being Written Redo L WL RAC-wide SGA dump krsh_dump_rsga acces
og s to RAC-wide SGA
Purge SRL SA standby redo logfile Coordinates access t
s o SRL by RFS and rec
overy process
Being Written Redo L WL Far Sync Fail Over Exclude multiple sim
og ultaneous failovers
Purge SRL SA MRP SRL access Coordinates access t
o SRL by RFS and rec
overy process
Being Written Redo L WL redo_db table update Serialize update to
og redo_db table
Being Written Redo L WL redo_log table updat Serialize update to
og e redo_log table
Being Written Redo L WL Switchover To Primar One and only one pro
og y cess executing switc
hover to primary
Being Written Redo L WL RFS global state con Serialize access to
og tention RFS global state
Being Written Redo L WL SNA access/locking Sync NoAffirm access
og /locking
Being Written Redo L WL Network Throttle Coordinate network t
og hrottle SGA access
LNS archiving log WR contention Coordinates access t
o logs by Async LNS
and ARCH/FG
RFS Logminer FLC RZ add element Synchronizes access
to the foreign log c
ache while a structu
re is being inserted
RFS Logminer FLC RZ remove element Synchronizes access
to the foreign log c
ache while a structu
re is being removed
Being Written Redo L WL contention Coordinates access t
og o redo log files and
archive logs
Redo Log Nab Computa RN contention Coordinates nab comp
tion utations of online l
ogs during recovery
Datafile Online in R DF contention Enqueue held by fore
AC ground or DBWR when
a datafile is brough
t online in RAC
Instance State IS contention Enqueue used to sync
hronize instance sta
te changes
PDB Instance State IP open/close PDB Enqueue used to sync
hronize instance sta
te changes for PDBs
PDB Recovery Operati PX PDB instance recover Enqueue used to sync
ons y hronize PDB shutdown
abort and PDB insta
nce recovery
File Set / Dictionar FS contention Enqueue used to sync
y Check hronize recovery and
file operations or
synchronize dictiona
ry check
File Set / Dictionar FS online log operation Enqueue used to sync
y Check hronize LGWR cached
open online logs and
online log clear/dr
op
Database Mount/Open DM contention Enqueue held by fore
ground or DBWR to sy
nchronize database m
ount/open or pluggab
le database open wit
h other operations
Database Mount/Open DM access control Enqueue held by fore
ground or GEN0 to sy
nchronizepluggable d
atabase open/close a
mong all HARIM insta
nces
Resilver / Repair RP contention Enqueue held when re
silvering is needed
or when datablock is
repaired from mirro
r
Online Datafile Move MV datafile move Held during online d
atafile move operati
on or cleanup
Redo Thread RT contention Thread locks held by
LGWR, DBW0, and RVW
R to indicate mounte
d or open status
Redo Thread RT thread internal enab Thread locks held by
le/disable CKPT to synchronize
thread enable and d
isable
Instance Recovery IR contention Synchronizes instanc
e recovery
Instance Recovery IR contention2 Synchronizes paralle
l instance recovery
and shutdown immedia
te
Instance Recovery IR global serialization serialize instance r
ecovery globally
Instance Recovery IR local serialization serialize instance r
ecovery with local d
ismount
Instance Recovery IR arbitrate instance r arbitrate parallel i
ecovery nstance recovery
Media Recovery MR contention Lock used to coordin
ate media recovery w
ith other uses of da
tafiles
Media Recovery MR standby role transit Lock used to disallo
ion w concurrent standby
role transition att
empt
Media Recovery MR multi instance redo Lock used to disallo
apply w concurrent recover
y attempt when MIRA
active
Media Recovery MR any role transition Lock used to disallo
w any concurrent rol
e transition attempt
Media Recovery MR PDB open Lock used to coordin
ate media recovery w
ith other uses of PD
B datafiles
Media Recovery MR datafile online Enqueue used to coor
dinate datafile offl
ine in RAC
Media Recovery MR adg instance recover Synchronizes multi i
y nstance recovery cle
anup with adg instan
ce recovery
Media Recovery MR preplugin recovery Lock used to disallo
w concurrent preplug
in recovery in the s
ame PDB
Media Recovery MR datafile pre-create Enqueue for datafile
pre-create task dur
ing standby recovery
Backup/Restore BR file shrink Lock held to prevent
file from decreasin
g in physical size d
uring RMAN backup
Backup/Restore BR proxy-copy Lock held to allow c
leanup from backup m
ode during an RMAN p
roxy-copy backup
Backup/Restore BR multi-section restor Lock held to seriali
e header ze file header acces
s during multi-secti
on restore
Backup/Restore BR multi-section restor Lock held to seriali
e section ze section access du
ring multi-section r
estore
Backup/Restore BR space info datafile Lock held to prevent
hdr update multiple process to
update the headers
at the same time
Backup/Restore BR request autobackup Lock held to request
controlfile autobac
kups
Backup/Restore BR perform autobackup Lock held to perform
a new controlfile a
utobackup
Backup/Restore BR perform catalog reco Lock held to seriali
very area ze catalog recovery
area search
NID ID contention Lock held to prevent
other processes fro
m performing control
file transaction whi
le NID is running
Backup/Restore spare BS Backup spare1 Backup spare1
enq
Backup/Restore spare BS Backup spare2 Backup spare2
enq
Backup/Restore spare BS Backup spare3 Backup spare3
enq
Backup/Restore spare BS Backup spare4 Backup spare4
enq
Backup/Restore spare BS Backup spare5 Backup spare5
enq
Backup/Restore spare BS Backup spare6 Backup spare6
enq
Backup/Restore spare BS Backup spare7 Backup spare7
enq
Backup/Restore spare BS Backup spare8 Backup spare8
enq
Backup/Restore spare BS Backup spare9 Backup spare9
enq
Backup/Restore spare BS Backup spare0 Backup spare0
enq
Auto BMR AB ABMR process start/s Lock held to ensure
top that only one ABMR i
s started in the clu
ster
Auto BMR AB ABMR process initial Lock held to ensure
ized that ABMR process is
initialized
ZDLRA Server ZR ZDLRA lock db Perform DB storage a
llocations on the Re
covery Appliance
ZDLRA Server ZR ZDLRA lock storage l Lock to use reserved
oc storage to perform
in line purging
ZDLRA Server ZR ZDLRA lock timer que Lock to perform time
ue r functions on the R
ecovery Appliance
ZDLRA Server ZR ZDLRA lock scheduler Lock to perform job
scheduling functions
on the Recovery App
liance
ZDLRA Server ZR ZDLRA lock API Lock to single strea
m API functions on t
he Recovery Applianc
e
ZDLRA Server ZR ZDLRA quiesce tasks Lock to prevent new
tasks from executing
ZDLRA Server ZR ZDLRA check quiesce Lock to verify that
tasks task execution is no
t being quiesced
ZDLRA Server ZR ZDLRA quiesce servle Lock to prevent new
ts servlet backups
ZDLRA Server ZR ZDLRA check servlet Lock to verify that
quiescence servlet backups are
not being quiesced
ZDLRA Server ZR ZDLRA serialize unre Lock to single strea
gister db m unregister db requ
ests
ZDLRA Server ZR ZDLRA run scheduler Hint that Recovery A
ppliance schedulers
may have new work
ZDLRA Server ZR ZDLRA purge storage Lock to restrict a s
loc ingle purging thread
per storage locatio
n
ZDLRA Server ZR ZDLRA spare enq 10 ZDLRA spare enq 10
ZDLRA Server ZR ZDLRA invalidate pla Lock to allow invali
ns dation of Recovery A
ppliance plans
ZDLRA Server ZR ZDLRA protect plans Lock to protect a Re
covery Appliance pla
n from becoming inva
lid
BA Container BC drop container group Group lock held whil
e dropping a contain
er group
BA Container BC create container Container lock held
while creating a con
tainer
BA Container BC group - create conta Group lock held whil
iner e creating a contain
er
BA Container BC drop container Container lock held
while dropping a con
tainer
BA Container BC group - create file Group lock held whil
e creating a contain
ed file
BA Contained File Id BI create file Enqueue held while a
entification contained file is c
reated
BA Contained File Id BI identify file Enqueue held while a
entification contained file is i
dentified
BA Contained File Id BI delete file Enqueue held while a
entification contained file is c
leaned up or deleted
BA Contained File Re BZ resize file Enqueue held while a
size contained file is r
esized
BA Group Rebuild/Val BV rebuild/validate gro Enqueue held while a
idate up container group is
rebuilding
LogMiner MN contention Synchronizes updates
to the LogMiner dic
tionary and prevents
multiple instances
from preparing the s
ame LogMiner session
Foreign Log Maintena ZL LogMiner foreign log Session-specific loc
nce metadata k to serialize addit
ions or removals fro
m the foreign log se
ction
Transportable Tables PL contention Coordinates plug-in
pace operation of transpo
rtable tablespaces
Pluggable Database CP Pluggable database r Synchronization
esetlogs
LogicalStandby SB logical standby meta Synchronizes Logical
data Standby metadata op
erations
LogicalStandby SB table instantiation Synchronizes table i
nstantiation and EDS
operations
Quiesce / Force Logg XR quiesce database Lock held during dat
ing abase quiesce
Quiesce / Force Logg XR database force loggi Lock held during dat
ing ng abase force logging
mode
Block Change Trackin CT global space managem Lock held during cha
g ent nge tracking space m
anagement operations
that affect the ent
ire change tracking
file
Block Change Trackin CT local space manageme Lock held during cha
g nt nge tracking space m
anagement operations
that affect just th
e data for one threa
d
Block Change Trackin CT change stream owners Lock held by one ins
g hip tance while change t
racking is enabled,
to guarantee access
to thread-specific r
esources
Block Change Trackin CT state Lock held while enab
g ling or disabling ch
ange tracking, to en
sure that it is only
enabled or disabled
by one user at a ti
me
Block Change Trackin CT state change gate 1 Lock held while enab
g ling or disabling ch
ange tracking in RAC
Block Change Trackin CT state change gate 2 Lock held while enab
g ling or disabling ch
ange tracking in RAC
Block Change Trackin CT CTWR process start/s Lock held to ensure
g top that only one CTWR p
rocess is started in
a single instance
Block Change Trackin CT reading Lock held to ensure
g that change tracking
data remains in exi
stence until a reade
r is done with it
Reclaimable Space RS file delete Lock held to prevent
file from accessing
during space reclai
mation
Reclaimable Space RS record reuse Lock held to prevent
file from accessing
while reusing circu
lar record
Reclaimable Space RS prevent file delete Lock held to prevent
deleting file to re
claim space
Reclaimable Space RS prevent aging list u Lock held to prevent
pdate aging list update
Reclaimable Space RS persist alert level Lock held to make al
ert level persistent
Reclaimable Space RS read alert level Lock held to read al
ert level
Reclaimable Space RS write alert level Lock held to write a
lert level
Flashback database l FL Flashback database l Synchronization
og og
Flashback database l FL Flashback db command Enqueue used to sync
og hronize Flashback Da
tabase and and delet
ion of flashback log
s.
Flashback Database FD Marker generation Synchronization
Flashback Database FD Tablespace flashback Synchronization
on/off
Flashback Database FD Flashback coordinato Synchronization
r
Flashback Database FD Flashback on/off Synchronization
Flashback Database FD Restore point create Synchronization
/drop
Flashback Database FD Flashback logical op Synchronization
erations
DML TM contention Synchronizes accesse
s to an object
Space Transaction ST contention Synchronizes space m
anagement activities
in dictionary-manag
ed tablespaces
Instance Undo TA contention Serializes operation
s on undo segments a
nd undo tablespaces
Transaction TX contention Lock held by a trans
action to allow othe
r transactions to wa
it for it
Transaction TX row lock contention Lock held on a parti
cular row by a trans
action to prevent ot
her transactions fro
m modifying it
Transaction TX allocate ITL entry Allocating an ITL en
try in order to begi
n a transaction
Transaction TX index contention Lock held on an inde
x during a split to
prevent other operat
ions on it
Cross-Instance Trans TW contention Lock held by one ins
action tance to wait for tr
ansactions on all in
stances to finish
Undo Segment US contention Lock held to perform
DDL on the undo seg
ment
Kti blr lock IM contention for blr Serializes block rec
overy for IMU txn
KTF map table enqueu TD KTF dump entries KTF dumping time/scn
e mappings in SMON_SC
N_TIME table
KTF broadcast TE KTF broadcast KTF broadcasting
KTCN REG enq CN race with txn during registration
KTCN REG enq CN race with reg during transaction c
ommit to see concurr
ent registrations
KTCN REG enq CN race with init during descriptor in
itialization
KTUCLO Master Slave CO master slave det enqueue held by Mast
enq er in Cleanout Optim
KTFA Recovery FE contention Serializes flashback
archive recovery
SGA Log Operation MC Securefile log Serializes log creat
ion/destruction with
log flushes
SGA Log-Bkt Flush MF flush bkgnd periodic Serializes flushes f
or a SGA log in bkgn
d
SGA Log-Bkt Flush MF creating swap in ins Serializes multiple
tance processes in creatin
g the swap space
SGA Log-Bkt Flush MF flush space Serializes flushes f
or a single SGA log
- space lack
SGA Log-Bkt Flush MF flush client Serializes flushes f
or a single SGA log
- client
SGA Log-Bkt Flush MF flush prior error Serializes flushes f
or a single SGA log
- error earlier
SGA Log-Bkt Flush MF flush destroy Serializes flushes f
or a single SGA log
- destroy
quiesce enq ZQ register SMU create
quiesce enq ZQ quiesce quiesce loading
Temporary File TF contention Serializes dropping
of a temporary file
Default Temporary Ta DT contention Serializes changing
blespace the default temporar
y table spaceand use
r creation
Segment High Water M HW contention Lock used to broker
ark the high water mark
during parallel inse
rts
Critical Block Alloc BE Critical Block Alloc Lock used to seriali
ation ation ze allocation of cri
tical blocks
Temporary Segment TS contention Serializes accesses
to temp segments
Format Block FB contention Ensures that only on
e process can format
data blcoks in auto
segment space manag
ed tablespaces
Sort Segment SS contention Ensures that sort se
gments created durin
g parallel DML opera
tions aren't prematu
rely cleaned up
Shrink Segment SK contention Serialize shrink of
a segment
In memory Dispenser DW contention Serialize in memory
dispenser operations
SaveUndo Segment SU contention Serializes access to
SaveUndo Segment
Tablespace TT contention Serializes DDL opera
tions on tablespaces
KTSJ Slave Task Canc SJ Slave Task Cancel Serializes cancellin
el g task executed by s
lave process
Flush Stat FH contention Serializes flush of
ILM stats to disk
in-memory TZ contention Serialize in-memory
area create/drop
in-memory segment IN contention Serialize in-memory
segment create/drop
in-memory TS ZB contention Serialize in-memory
tablespace create/dr
op
Sequence Cache SQ contention Lock to ensure that
only one process can
replenish the seque
nce cache
Direct Loader High W HV contention Lock used to broker
ater Mark the high water mark
during parallel inse
rts
Direct Loader Index DL contention Lock to prevent inde
Creation x DDL during direct
load
Hash Queue HQ contention Synchronizes the cre
ation of new queue I
Ds
Queue Page HP contention Synchronizes accesse
s to queue pages
Write gather local e WG delete fso acquire lobid local
nqueue enqueue when deletin
g fso
Write gather local e WG lock fso acquire lobid local
nqueue enqueue when locking
fso
Serialize Lock reque SL get lock sending lock req to
st LCK0
Serialize Lock reque SL escalate lock sending lock escalat
st e to LCK0
Serialize Lock reque SL get lock for undo sending lock req for
st undo to LCK0
Compression Analyzer ZH compression analysis Synchronizes analysi
s and insert into co
mpression$, prevents
multiple threads an
alyzing the same tab
le during a load
IM segment populate SZ contention Lock used to seriali
ze in-memory segment
populates
IM FastStart Admin ZC FS Seg contention Serialize FS segment
creation
IM FastStart CU ZD FS CU mod Serialize FS savepoi
nt mod
IM chunk populate SY IM populate by other Serialize populate o
session f in-memory chunk
Join group dictionar JZ Join group dictionar Synchronizes modific
y y ations to im_domain$
and im_joingroup$
Diana Versioning DV contention Synchronizes access
to lower-version Dia
na (PL/SQL intermedi
ate representation)
Shared Object SO contention Synchronizes access
to Shared Object (PL
/SQL Shared Object M
anager)
Runtime Fixed Table TP contention Lock held during pur
Purge ge and dynamic recon
figuration of fixed
tables.
Materialized View Fl RW MV metadata contenti Lock held by CREATE/
ags on ALTER/DROP materiali
zed viewwhile updati
ng materialized view
flags in detail tab
les
Outline Cache OC contention Synchronizes write a
ccesses to the outli
ne cache
Outline Name OL contention Synchronizes accesse
s to a particular ou
tline name
Cursor CU contention Recovers cursors in
case of death while
compiling
Edition Lock AE lock Prevent Dropping an
edition in use
Password File PF contention Synchronizes accesse
s to the password fi
le
Password File Metada PZ flush passwordfile m Synchronizes changes
ta Cache etadata to the password fil
e metadata cache
Password File Metada PZ load passwordfile me Synchronizes read an
ta Cache tadata d writes to the pass
word file metadata c
ache
Label Security IL contention Synchronizes accesse
s to internal label
data structures
Label Security cache CL drop label Synchronizes accesse
s to label cache whe
n dropping a label
Label Security cache CL compare labels Synchronizes accesse
s to label cache for
label comparison
OLS groups SG OLS Add Group Synchronize access t
o ols$groups when zl
llabGroupTreeAddGrou
p does a read
OLS groups SG OLS Create Group Synchronize access t
o ols$groups when cr
eating a group
OLS groups SG OLS Drop Group Synchronizing access
to ols$groups when
dropping a group
OLS groups SG OLS Alter Group Pare Synchronizing access
nt to ols$groups when
alter group parent
Label Security Profi OP OLS Store user entri Synchronizing access
le es to ols$user when in
serting user entries
Label Security Profi OP OLS Cleanup unused p Synchronizing access
le rofiles to ols$profile when
deleting unused pro
files
Column Key CC decryption decrypting and cachi
ng column key
Master Key MK contention changing values in e
nc$
Encryption Wallet OW initialization initializing the wal
let context
Encryption Wallet OW termination terminate the wallet
context
EQ_NAME EQ_TYPE REQ_REASON REQ_DESCRIPTION
-------------------- -------------------- -------------------- --------------------
wallet_set_mkey RK set key wallet master key re
key
wallet_set_mkey RK queue wallet and TS coordinate with tabl
keys espace key rekey
HSM cache HC HSM cache write add or delete from t
he HSM cache
HSM cache HC HSM cache read read from the HSM ca
che
RAC Encryption Walle RL RAC wallet lock RAC wallet lock
t Lock
DV Policy Admin API PJ modify DV policy lock held for modify
ing Database Vault p
olicy
DV Policy Admin API PJ read DV policy lock held for readin
g Database Vault pol
icy
Global Context Actio ZZ update hash tables lock held for updati
n ng global context ha
sh tables
Audit Partition ZA add std audit table lock held to add par
partition tition to std audit
table
FGA Partition ZF add fga audit table lock held to add par
partition tition to fga audit
table
Spillover Audit file ZS excl access to spill lock held while writ
s audit file ing to/renaming/dele
ting spillover audit
file
Transfer Unified Aud UT transfer audit recor lock held while exec
it Records ds uting transfer proce
dure
CBAC Master Lock CB role operation Synchronizes accesse
s to the CBAC roles
cached in KGL
Privilege Capture AP PA modify a privilege c lock held for during
I apture modify a privilege
capture
Privilege Capture AP PA read a privilege cap lock held for during
I ture reading privilege c
aptur status
Enqueue for kzppctxs PC update privilege cap lock held while modi
ture info fying kzppctxs in SG
A
Enqueue for kzppctxs PC read privilege captu lock held while read
re info ing kzppctxs in SGA
Distributed Transact DX contention Serializes tightly c
ion oupled distributed t
ransaction branches
Distributed Recovery DR contention Serializes the activ
e distributed recove
ry operation
Global Transaction B BB 2PC across RAC insta 2PC distributed tran
ranch nces saction branch acros
s RAC instances
Job Queue Date JD contention Synchronizes dates b
etween job queue coo
rdinator and slave p
rocesses
Job Queue JQ contention Lock to prevent mult
iple instances from
running a single job
Online DDLs OD Serializing DDLs Lock to prevent conc
urrent online DDLs
DbsDriver DB contention Synchronizes modific
ation of database wi
de supplementalloggi
ng attributes
Materialized View Lo MD contention Lock held during mat
g DDL erialized view log D
DL statements
Materialized View Re MS contention Lock held during mat
fresh Log erialized view refre
sh to setup MV log
SPM Autopurge AP contention This enqueue is used
to serialize the pu
rging of SQL plan ba
selines
SQLQ Autopurge RH quarantine This enqueue is used
to serialize the pu
rging of SQL quarant
ine configurations
Remote PX Process Sp PI contention Communicates remote
awn Status Parallel Execution S
erver Process creati
on status
PX Process Reservati PS contention Parallel Execution S
on erver Process reserv
ation and synchroniz
ation
Instance DP Array DA Slave Process Array Slave Process Spawn
reservation and sync
hronization
KSXA Test Affinity D AY contention Affinity Dictionary
ictionary test affinity synchr
onization
Temp Object TO contention Synchronizes DDL and
DML operations on a
temp object
In Memory Temp Objec TG IMCDT global resourc Allocate on imcdt gl
t e obal resource
In Memory Temp Objec TI IMCDT object HT Allocate on imcdt ob
t HT ject HT
Private Temp Table s ZP Private Temporary Ta Synchronizes add/dro
ynchronize ble p of Private Temp Ta
ble with DBA_PRIVATE
_TEMP_TABLES
In-Mem Temp Table Me IT contention Synchronizes accesse
ta Creation s to a temp object's
metadata
BLOOM FILTER BF allocation contentio Allocate a bloom fil
n ter in a parallel st
atement
BLOOM FILTER BF PMON Join Filter cle PMON bloom filter re
anup covery
Result Cache: Enqueu RC Result Cache: Conten Coordinates access t
e tion o a result-set
SQL STATEMENT QUEUE JX SQL statement queue statement
SQL STATEMENT QUEUE JX cleanup of queue release SQL statemen
t resources
RAC Load RD RAC load update RAC load inf
o
KEY VECTOR KV IMA key vector acces Access a key vector
s in an IMA query
MGA service MG MGA allocation synchronize MGA serv
ice MGA allocation
MGA service MG client shared contex synchronize MGA serv
t allocation ice client shared co
ntext allocation
Kupp Process Startup KP contention Synchronizes kupp pr
ocess startup
Synchronized Replica SR contention Coordinates replicat
tion ion / streams operat
ions
Replication Global RG Apply coord start/st Coordinates instance
op -wide replication /
streams operations
Streams Table Instan SI contention Prevents multiple st
tiation reams tabel instanti
ations
File Group ZG contention Coordinates file gro
up operations
Internal IA contention
Materialized View JI contention Lock held during mat
erialized view opera
tions (like refresh,
alter) to prevent c
oncurrent operations
on the same materia
lized view
Alter Tablespace AT contention Serializes 'alter ta
blespace' operations
Cleanup querycache r CQ contention Serializes access to
egistrations cleanup client quer
y cache registration
s
Emon-SRVNTFN_Q Creat AZ AQ_SRVNTFN_Q Creatio Create AQ_SRVNTFN_Q
e n by single Emon slave
only
Session Migration SE contention Synchronizes transpa
rent session migrati
on operations
User-defined UL contention Lock used by user ap
plications
Queue table enqueue TQ TM contention TM access to the que
ue table
Queue table enqueue TQ DDL contention TM access to the que
ue table
Queue table enqueue TQ INI contention TM access to the que
ue table
Queue table enqueue TQ DDL-INI contention Streams DDL on queue
table
Queue table enqueue TQ INI sq contention INIT access to the q
ueue tables
Queue table enqueue TQ MC free sync at cros Shift dequeue affini
s job start ty to destination in
stance
Queue table enqueue TQ MC free sync at cros Shift dequeue affini
s job stop ty to source instanc
e
Queue table enqueue TQ MC free sync at cros Stop a cross job str
s job end eam
Queue table enqueue TQ MC free sync at expo Export a subshard in
rt subshard cross stream
Queue table enqueue TQ create eviction tabl post upgrade creatio
e n of eviction table
Queue table enqueue TQ TM Job cache initial TM Job cache Initial
ization ization
Queue table enqueue TQ TM Job cache use TM Job cache usage
Queue table enqueue TQ sq TM contention SQ TM access to the
queue table
Queue table enqueue TQ LB drop volatile sha LB drop volatile sha
rd rd
Enqueue-Cross SCN RQ Enqueue commit uncac Enqueue commit uncac
hed hed
Enqueue-Cross SCN RQ Enqueue commit cache Enqueue commit rac c
d ached
Enqueue-Cross SCN RQ Dequeue update scn Dequeue updating scn
Enqueue-Cross SCN RQ Parallel cross updat Parallel cross(updat
e scn e scn) - truncate su
bshard
Enqueue-Cross SCN RQ Cross update scn Cross process updati
ng disk
Enqueue-Cross SCN RQ Trucate subshard Truncate - Cross(exp
ort) subshard
Enqueue-Cross SCN RQ Cross export subshar Cross(export) - trun
d cate subshard
Enqueue-Cross SCN RQ Cross import subshar Cross(import) - free
d shadow shard
Enqueue-Cross SCN RQ Free shadow shard Free shadow - Cross(
import) shard
Enqueue-Cross SCN RQ AQ indexed cached co AQ indexed cached co
mmit mmit
Enqueue-Cross SCN RQ AQ uncached commit W AQ uncached commit W
M update M update
Enqueue-Cross SCN RQ AQ uncached dequeue AQ uncached dequeue
Enqueue-Cross SCN RQ AQ Eq Ptn Mapping AQ Eq Ptn Mapping
Enqueue-Cross SCN RQ AQ Dq Ptn Mapping AQ Dq Ptn Mapping
Enqueue-Cross SCN RQ AQ Trnc mem free AQ Trnc mem free
Enqueue-Cross SCN RQ AQ Trnc mem free rem AQ Trnc mem free rem
ote ote
Enqueue-Cross SCN RQ AQ Trnc mem free by AQ Trnc mem free kws
LB lb
Enqueue-Cross SCN RQ AQ Trnc mem free by AQ Trnc mem free kws
CP mcx
Enqueue-Cross SCN RQ AQ Enq commit incarn AQ incarnation numbe
ation wrap r wrap
Enqueue-Cross SCN RQ AQ Rule evaluation s AQ segment load kwse
egment load
Enqueue-Cross SCN RQ AQ Evict: block trun AQ message cache man
cate agement
Enqueue-Cross SCN RQ AQ Unevict PGA: setu AQ message cache man
p subscriber agement
Enqueue-Cross SCN RQ AQ Unevict PGA: Queu AQ message cache man
e View agement
Enqueue-Cross SCN RQ AQ Shid Gen AQ Shid Gen
Enqueue-Cross SCN RQ AQ Enq commit block AQ RAC enqueue commi
truncate t
Enqueue-Cross SCN RQ AQ Cross update scn AQ Cross uncached co
for delay nversion
Enqueue-Cross SCN RQ AQ Cross Shard mem f AQ RAC message forwa
ree rding end
Enqueue-Cross SCN RQ AQ rollback retry co AQ retry count
unt update
Enqueue-Cross SCN RQ AQ cached commit WM AQ cached commit WM
update update
Enqueue-Cross SCN RQ AQ cached dequeue by AQ cached dequeue by
condition condition
Enqueue-Delete Rule KR Drop rule force Drop rule force
Enqueue-Delete Rule KR Add rule to ruleset Synchronize with dro
p rule
Enqueue-Delete Rule KR Remove rule from rul Syncronize remove ru
eset le from ruleset
LDAP Parameter DP contention Synchronizes access
to LDAP parameters
AQ Notification Mail MH contention Lock used for recove
Host ry when setting Mail
Host for AQ e-mail
notifications
AQ Notification Mail ML contention Lock used for recove
Port ry when setting Mail
Port for AQ e-mail
notifications
AQ Notification Prox PH contention Lock used for recove
y ry when setting Prox
y for AQ HTTP notifi
cations
AQ Notification Send SF contention Lock used for recove
er ry when setting Send
er for AQ e-mail not
ifications
AQ Notification No-P XH contention Lock used for recove
roxy ry when setting No P
roxy Domains for AQ
HTTP notifications
AQ Notification Wate WA contention Lock used for recove
rmark ry when setting Wate
rmark for memory usa
ge in AQ notificatio
ns
Queue Partitioning l AQ QPT fg map dqpt kwsptGetOrMapDqPtn
ocal enqueue
Queue Partitioning l AQ QPT fg map qpt kwsptGetOrMapQPtn
ocal enqueue
Queue Ptning global PQ QPT add qpt kwsptLoadQCache: Add
enq Q Partitions.
Queue Ptning global PQ QPT drop qpt kwsptLoadQCache:Drop
enq Q Partitions.
Queue Ptning global PQ QPT add dqpt kwsptLoadDqCache: Ad
enq d DQ Partitions.
Queue Ptning global PQ QPT drop dqpt kwsptLoadDqCache:Dro
enq p DQ Partitions.
Queue Ptning global PQ QPT add qpt fg kwsptMapQPtn: Add Q
enq Partitions in foregr
ound
Queue Ptning global PQ QPT add dqpt fg kwsptMapDqPtn:Drop D
enq Q Partitions in fore
ground
Queue Ptning global PQ QPT Trunc kwsptChkTrncLst:Trun
enq cate
Queue Ptning global PQ QPT LB Trunc sync kwslbFreShadowShrd:L
enq B syncronization wit
h Truncate
Queue Ptning global PQ QPT XSTART Trunc syn kwsmcxMoreToExport:X
enq c START syncronization
with Truncate
non durable sub bmap BA SUBBMAP contention subscriber access to
alloc bitmap
TEXT: Index Specific CX TEXT: Index Specific Index Specific Lock
Lock Lock on CTX index
TEXT: Generic Lock OT TEXT: Generic Lock CTX Generic Locks
XDB Configuration XC XDB Configuration Lock obtained when i
ncrementing XDB conf
iguration version nu
mber
Data Guard Broker RF synch: DG Broker met Ensures r/w atomicit
adata y of DG configuratio
n metadata
Data Guard Broker RF atomicity Ensures atomicity of
log transport setup
Data Guard Broker RF Broker Chief Lock Used to synchronize
broker activity
Data Guard Broker RF synchronization: aif Synchronizes apply i
o master nstance failure dete
ction and failover o
peration
Data Guard Broker RF new AI Synchronizes selecti
on of the new apply
instance
Data Guard Broker RF synchronization: cri Synchronizes critica
tical ai l apply instance amo
ng primary instances
Data Guard Broker RF RF - Database Automa Means for detecting
tic Disable when database is bei
ng automatically dis
abled
Data Guard Broker RF FSFO Observer Heartb Captures recent Fast
eat -Start Failover Obse
rver heartbeat infor
mation
Data Guard Broker RF DG Broker Current Fi Identifies which con
le ID figuration metadata
file is current
Data Guard Broker RF FSFO Primary Shutdow Records when FSFO Pr
n suspended imary Shutdown is su
spended
Data Guard Broker RF Broker State Lock Captures database-wi
de broker state
Data Guard Broker RF FSFO string buffer Makes a FSFO-related
string available ac
ross RAC instances
Data Guard Broker RF Broker NSV Lock Used to synchronize
NSV creation/termina
tion
Data Guard Broker RF Broker LSBY FO Lock Used to force lsby f
ailover teardown on
one instance
Analytic Workspace AW AW$ table lock Global access synchr
onization to the AW$
table
Analytic Workspace AW AW state lock Row lock synchroniza
tion for the AW$ tab
le
Analytic Workspace AW user access for AW Synchronizes user ac
cesses to a particul
ar workspace
Analytic Workspace AW AW generation lock In-use generation st
ate for a particular
workspace
Analytic Workspace G AG contention Synchronizes generat
eneration ion use of a particu
lar workspace
MultiWriter Object A AO contention Synchornizes access
ccess to objects and scala
r variables
OLAPI Histories OQ xsoqhiAlloc Synchronizes access
to olapi history all
ocation
OLAPI Histories OQ xsoqhiFlush Synchronizes access
to olapi history flu
shing
OLAPI Histories OQ xsoq*histrecb Synchronizes access
to olapi history par
ameter CB
OLAPI Histories OQ xsoqhiClose Synchronizes access
to olapi history clo
sing
OLAPI Histories OQ xsoqhistrecb Synchronizes access
to olapi history glo
bals
ASM Enqueue AM client registration Registers DB instanc
e to ASM client stat
e object hash
ASM Enqueue AM shutdown Prevent DB instance
registration during
ASM instance shutdow
n
ASM Enqueue AM rollback COD reserva Reserve a rollback C
tion OD entry
ASM Enqueue AM background COD reser Reserve a background
vation COD entry
ASM Enqueue AM ASM cache freeze Start ASM cache free
ze
ASM Enqueue AM ASM ACD Relocation Block ASM cache free
ze
ASM Enqueue AM group use Client group use
ASM Enqueue AM group block ASM group block
ASM Enqueue AM ASM File Destroy Prevent same file de
letion race
ASM Enqueue AM ASM User Prevents a user from
being dropped if it
owns any open files
ASM Enqueue AM ASM Password File Up Allow one ASM passwo
date rd file update per c
luster at a time
ASM Enqueue AM ASM Amdu Dump Allow only one AMDU
dump when block read
failure
ASM Enqueue AM disk offline Synchronizes disk of
flines
ASM Enqueue AM ASM reserved Check id1 of call fo
r specific purpose
ASM Enqueue AM block repair Serializes block rep
airs
ASM Enqueue AM ASM disk based alloc Synchronizes disk ba
/dealloc sed allocations/deal
locations
ASM Enqueue AM ASM file descriptor Serializes access to
ASM file descriptor
s
ASM Enqueue AM ASM file relocation Serializes file relo
cation shrink and dr
op
ASM Enqueue AM ASM SR relocation Serializes file relo
cation and SR open
ASM Enqueue AM ASM Grow ACD Serializes growing A
SM ACD
ASM Enqueue AM ASM DD update SrRloc Serializes DD update
for SrRloc
ASM Enqueue AM ASM file chown Prevents new owners
of open files from b
eing dropped
ASM Enqueue AM Register with IOServ Serializes the regis
er tration of the datab
ase with IOServer
ASM Enqueue AM ASM metadata replica Serializes metadata
tion replication
ASM Enqueue AM SR slice Clear/Mark Serialize clear/assi
gnment for SR slices
ASM Enqueue AM Enable Remote ASM Lock held while enab
ling remote asm
ASM Enqueue AM Disable Remote ASM Lock held while disa
bling remote asm
ASM Enqueue AM Credential creation Lock held while crea
ting credentials
ASM Enqueue AM Credential deletion Lock held while dele
ting credentials
ASM Enqueue AM ASM file access req Synchronizes file ac
cess per client
ASM Enqueue AM ASM client operation Synchronizes client
operations and shutd
own
ASM Enqueue AM ASM client check Synchronizes client
check, kill and regi
ster
ASM Enqueue AM ASM ATB COD creation ASM ATB COD creation
ASM Enqueue AM Create default DG ke ASM audit create def
y in OCR ault DG key in OCR
ASM Enqueue AM ASM Audit file Delet ASM Audit file Delet
e e
ASM Enqueue AM ASM Audit file Clean ASM Audit file Clean
up up
ASM Enqueue AM ASM VAT migration ASM VAT migration
ASM Enqueue AM Update SR nomark fla Synchronize updating
g of Staleness Regist
ry nomark flag
ASM Enqueue AM ASM VAL cache ASM VAL cache
ASM Enqueue AM ASM SR Segment Reuse Synchronizes SR Segm
ent Reuse enqueue ac
quisition
ASM Enqueue AM ASM SR Segment Reuse Synchronizes Segment
Lookup Reuse client lookup
ASM Enqueue AM ASM SR Batch Allocat Serialize SR batch a
ion llocation
ASM Enqueue AM ASM Sparse Disk IOCT Serialize sparse dis
L k IOCTLs
ASM Enqueue AM ASM VAM Active Serialize access to
_vam_active attribut
e
ASM Enqueue AM ASM Split Mirror Fil Serialize file creat
e Create e with split mirror
operations
ASM Enqueue AM ASM Split Mirror Fil Serializes file dele
e Delete te with split mirror
operations
ASM Enqueue AM ASM Mirror Prepare Serialize PREPARE wi
th other operations
ASM Enqueue AM ASM Mirror Split Serialize SPLIT with
other operations
ASM Enqueue AM ASM Drop Mirror Serialize DROP MIRRO
R with other operati
ons
ASM Enqueue AM ASM PDB Mirror Split Serialize PDB SPLIT
with other operation
s
ASM Enqueue AM DB Mirror Prepare Serialize PREPARE wi
th other split mirro
r operations
ASM Enqueue AM DB Drop Mirror Copy Serialize DROP MIRRO
R with other split m
irror operations
ASM Enqueue AM DB Mirror Split Serialize SPLIT with
split mirror operat
ions
ASM Enqueue AM PDB Mirror Split Serialize PDB SPLIT
with split mirror op
erations
ASM Enqueue AM Create Prepare Child Serialize split mirr
file group or PREPARE with Chan
ge Redundancy
ASM Enqueue AM Change file group re Serialize Change Red
dundancy undancy with split m
irror PREPARE
ASM Enqueue AM ASM Split Mirror ODM Serialize ODM file c
File Crt reate with split mir
ror operations
ASM Enqueue AM ASM Split Mirror ODM Serializes ODM file
File Del delete with split mi
rror operations
ASM Enqueue AM ASMB Startup Serialize startup of
multiple ASMB backg
rounds
ASM Enqueue AM ASMB Renew Serialize renew of d
iskgroups among mult
iple ASMB background
s
ASM Enqueue AM ASM: group unblock Serialize group unbl
ock
ASM Enqueue AM ASM file create Serializes ASM file
create
ASM Enqueue AM ASM ATE conversion ASM ATE conversion
ASM Enqueue AM ASM resync from ATE Serializes work to e
nable resync from AT
Es
ASM Enqueue AM ASM Split Status Wri Serialize SPLIT STAT
te US Write
ASM Enqueue AM ASM Split Status Rea Serialize SPLIT STAT
d US Read
ASM Enqueue AM ASM Client Assisted ASM client assisted
Offline offline
ASM Enqueue AM ASM Client Assisted Check pending client
Offline Chk assisted offline
ASM Instance Enqueue CM gate serialize access to
instance enqueue
ASM Instance Enqueue CM instance indicate ASM diskgro
up is mounted
ASM Instance Enqueue CM diskgroup dismount serialize asm diskgr
oup dismount
ASM Extent Relocatio XQ recovery prevent relocation d
n Enqueue uring _recovery_asse
rts checking
ASM Extent Relocatio XQ relocation wait for recovery be
n Enqueue fore doing relocatio
n
ASM Extent Relocatio XQ purification wait for relocation
n Enqueue before doing block p
urification
ASM Disk AU Lock AD allocate AU Synchronizes accesse
s to a specific ASM
disk AU
ASM Disk AU Lock AD deallocate AU Synchronizes accesse
s to a specific ASM
disk AU
ASM Disk AU Lock AD relocate AU Synchronizes accesse
s to a specific ASM
disk AU
ASM Disk AU Lock AD flush writes to AU Waits for pending wr
ites to an AU to be
flushed
ASM Disk Online Lock DO disk online Synchronizes disk on
lines and their reco
very
ASM Disk Online Lock DO disk online recovery Synchronizes disk on
lines and their reco
very
ASM Disk Online Lock DO Staleness Registry c Synchronizes Stalene
reate ss Registry creation
ASM Disk Online Lock DO startup of MARK proc Synchronizes startup
ess of MARK process
ASM Extent Fault Loc XL fault extent map Keep multiple proces
k ses from faulting in
the same extent chu
nk
ASM Disk Group Modif DG contention Synchronizes accesse
ication s to ASM disk groups
ASM Local Disk Group DD contention Synchronizes local a
ccesses to ASM disk
groups
ASM Disk Header HD contention Serializes accesses
to ASM SGA data stru
ctures
Diskgroup number gen DN contention Serializes group num
erator ber generations
ASM File Access Lock FA access file Synchronizes accesse
s to open ASM files
ASM Extent Relocatio RX relocate extent Synchronizes relocat
n Lock ing ASM extents
ASM Extent Relocatio RX unlock extent Synchronizes unlocki
n Lock ng ASM extents
Disk Group Recovery FR contention begin recovery of di
sk group
Disk Group Recovery FR use the thread indicate this ACD th
read is alive
Disk Group Recovery FR recover the thread wait for lock domain
detach
ACD Relocation Gate FG serialize ACD reloca only 1 process in th
Enqueue te e cluster may do ACD
relocation in a dis
k group
ACD Relocation Gate FG FG redo generation e resolve race conditi
Enqueue nq race on to acquire Disk G
roup Redo Generation
Enqueue
ACD Relocation Gate FG LGWR redo generation resolve race conditi
Enqueue enq race on to acquire Disk G
roup Redo Generation
Enqueue
Disk Group Redo Gene FT allow LGWR writes allow LGWR to genera
ration te redo in this thre
ad
Disk Group Redo Gene FT disable LGWR writes prevent LGWR from ge
ration nerating redo in thi
s thread
Disk Group Chunk Mou FC open an ACD thread LGWR opens an ACD th
nt read
Disk Group Chunk Mou FC recover an ACD threa SMON recovers an ACD
nt d thread
ACD Xtnt Info CIC FX issue ACD Xtnt Reloc ARB relocates ACD ex
ation CIC tent
ASM Rollback Recover RB contention Serializes ASM rollb
y ack recovery operati
ons
IOServer Client IC IOServer clientID Gets a unique client
ID
IOServer File IF file open File Open
IOServer File IF file close File Close
ASM Partnership and PT contention Synchronizes access
Status Table to ASM PST metadata
ASM Partnership and PT ASM Storage May Spli Synchronize storage
Status Table t split check
ASM Attributes Enque KQ access ASM attribute Synchronization of A
SM cached attributes
ASM volume locks AV persistent DG number prevent DG number co
llisions
ASM volume locks AV volume relocate Serialize relocating
volume extents
ASM volume locks AV AVD client registrat Serialize inst reg a
ion nd first DG use
ASM volume locks AV add/enable first vol Serialize taking the
ume in DG AVD DG enqueue
AWR Flush WF contention This enqueue is used
to serialize the fl
ushing of snapshots
AWR CDB-Wide Table L WT contention This enqueue seriali
ock zes CDB-Wide Operati
on on AWR Table
AWR Purge WP contention This enqueue handles
concurrency between
purging and baselin
es
DBFUS FU contention This enqueue is used
to serialize the ca
pture of the DB Feat
ure Usage
and High Water Mark
Statistics
AWR undostat stat fl UF undo stat flush per This enqueue is used
ush for PDB PDB to serialize undo s
tat flush per PDB
AWR import WI AWR import Serialize the import
of AWR dump files
AWR auto-export WE AWR auto-export Serialize auto-expor
t of AWR data
AWR mail package ret WD AWR mail package ret Serialize retrieving
rieval rieval AWR mail package
SQL Tuning Base Exis TB SQL Tuning Base Cach Synchronizes writes
tence Cache e Update to the SQL Tuning Ba
se Existence Cache
SQL Tuning Base Exis TB SQL Tuning Base Cach Synchronizes writes
tence Cache e Load to the SQL Tuning Ba
se Existence Cache
Active Session Histo SH contention Should seldom see th
ry Flushing is contention as thi
s Enqueue is always
acquired in no-wait
mode
Advisor Framework AF task serialization This enqueue is used
to serialize access
to an advisor task
MMON restricted sess MO contention Serialize MMON opera
ion tions for restricted
sessions
MMON Management MM MMON Autotask schedu Serialize MMON Autot
ling ask scheduling
Log Lock TL contention Serializes threshold
log table read and
update
Threshold Chain TH metric threshold eva Serializes threshold
luation in-memory chain acc
ess
Auto Task Serializat TK Auto Task Serializat Lock held by MMON to
ion ion prevent other MMON
spawning of Autotask
Slave
Auto Task Serializat TK Auto Task Slave Lock Serializes spawned A
ion out utotask Slaves
Workload Capture and RR contention Concurrent invocatio
Replay n of DBMS_WORKLOAD_*
package API
Real-Time ADDM Flood RA RT ADDM flood contro Flood control in RAC
Control l . Acquired in no-wai
t.
MWIN Schedule MW contention This enqueue is used
to serialize the ca
libration of the
manageability
schedules with the
Maintenance Window
TOP UPD TU UMF topology Enqueue used to seri
alize updates to top
ology data
EQ_NAME EQ_TYPE REQ_REASON REQ_DESCRIPTION
-------------------- -------------------- -------------------- --------------------
Job Scheduler JS job run lock - synch Lock to prevent job
ronize from running elsewhe
re
Job Scheduler JS job recov lock Lock to recover jobs
running on crashed
RAC inst
Job Scheduler JS wdw op Lock got when doing
window open/close
Job Scheduler JS evt notify Lock got during even
t notification
Job Scheduler JS aq sync Scheduler evt code a
nd AQ sync
Job Scheduler1 JG queue lock Lock on internal sch
eduler queue
Job Scheduler1 JG q mem clnup lck Lock obtained when c
leaning up q memory
Job Scheduler1 JG contention Synchronizes accesse
s to the job cache
Job Scheduler1 JG sch locl enqs Scheduler non-global
enqueues
Job Scheduler1 JG evt notify Lock got during even
t notification
Job Scheduler1 JG evtsub add Lock got when adding
subscriber to event
q
Job Scheduler1 JG evtsub drop Lock got when droppi
ng subscriber to eve
nt q
DBKR AU ADR Purge Operation This enqueue is used
to serialize ADR pu
rge operation
Auto Online Exadata XD ASM disk drop/add Serialize Auto Drop/
disks Add Exadata disk ope
rations
Auto Online Exadata XD ASM disk ONLINE Serialize ONLINE Exa
disks data disk operations
Auto Online Exadata XD ASM disk OFFLINE Serialize OFFLINE Ex
disks adata disk operation
s
PDB SGA ALLOCATION SN PDB SGA allocation Synchronize PDB SGA
allocation
PDB SGA ALLOCATION SN PDB SGA free Synchronize PDB SGA
Free
PDB SGA ALLOCATION SN PDB SGA protection Synchronize PDB SGA
Protection
PDB DDL Operations PB PDB Lock Enqueue used to sync
hronize PDB DDL oper
ations