ABLock held to ensure that ABMR process is initialized

ABLock held to ensure that only one ABMR is started in the cluster

ADSynchronizes accesses to a specific ASM disk AU

AEPrevent Dropping an edition in use

AFThis enqueue is used to serialize access to an advisor task

AGSynchronizes generation use of a particular workspace

AMASM group block

AMAllow one ASM password file update per cluster at a time

AMAllow only one AMDU dump when block read failure

AMBlock ASM cache freeze

AMCheck id1 of call for specific purpose

AMClient group use

AMPrevent DB instance registration during ASM instance shutdown

AMPrevent same file deletion race

AMPrevents a user from being dropped if it owns any open files

AMRegisters DB instance to ASM client state object hash

AMReserve a background COD entry

AMReserve a rollback COD entry

AMSerializes access to ASM file descriptors

AMSerializes block repairs

AMStart ASM cache freeze

AMSynchronizes disk based allocations / deallocations

AMSynchronizes disk offlines

AOSynchornizes access to objects and scalar variables

ASSynchronizes new service activation

ATSerializes 'alter tablespace' operations

AVSerialize inst reg and first DG use

AVSerialize relocating volume extents

AVSerialize taking the AVD DG enqueue

AVprevent DG number collisions

AWGlobal access synchronization to the AW $ table

AWIn-use generation state for a particular workspace

AWRow lock synchronization for the AW $ table

AWSynchronizes user accesses to a particular workspace

AYAffinity Dictionary test affinity synchronization

BB2PC distributed transaction branch across RAC instances

BFAllocate a bloom filter in a parallel statement

BFPMON bloom filter recovery

BRLock held to allow cleanup from backup mode during an RMAN proxy-copy backup

BRLock held to perform a new controlfile autobackup

BRLock held to prevent file from decreasing in physical size during RMAN backup

BRLock held to prevent multiple process to update the headers at the same time

BRLock held to request controlfile autobackups

BRLock held to serialize file header access during multi-section restore

BRLock held to serialize section access during multi-section restore

CASynchronizes various IO calibration runs

CFSynchronizes accesses to the controlfile

CICoordinates cross-instance function invocations

CLSynchronizes accesses to label cache for label comparison

CLSynchronizes accesses to label cache when dropping a label

CMindicate ASM diskgroup is mounted

CMserialize access to instance enqueue

CMserialize asm diskgroup dismount

CNduring descriptor initialization

CNduring registration

CNduring transaction commit to see concurrent registrations

COenqueue held be Master in Cleanout Optim

CQSerializes access to cleanup client query cache registrations

CRCoordinates fast block range reuse ckpt

CTLock held by one instance while change tracking is enabled, to guarantee access to thread-specific resources

CTLock held during change tracking space management operations that affect just the data for one thread

CTLock held during change tracking space management operations that affect the entire change tracking file

CTLock held to ensure that change tracking data remains in existence until a reader is done with it

CTLock held to ensure that only one CTWR process is started in a single instance

CTLock held while enabling or disabling change tracking in RAC

CTLock held while enabling or disabling change tracking, to ensure that it is only enabled or disabled by one user at a time

CURecovers cursors in case of death while compiling

CXIndex Specific Lock on CTX index

DBSynchronizes modification of database wide supplementallogging attributes

DDSynchronizes local accesses to ASM disk groups

DFEnqueue held by foreground or DBWR when a datafile is brought online in RAC

DGSynchronizes accesses to ASM disk groups

DLLock to prevent index DDL during direct load

DMEnqueue held by foreground or DBWR to syncrhonize database mount / open with other operations

DNSerializes group number generations

DORepresents an active disk online operation

DOSynchronizes Staleness Registry creation

DOSynchronizes disk onlines and their recovery

DOSynchronizes startup of MARK process

DPSynchronizes access to LDAP parameters

DRSerializes the active distributed recovery operation

DSPrevents a database suspend during LMON reconfiguration

DTSerializes changing the default temporary table spaceand user creation

DVSynchronizes access to lower-version Diana (PL / SQL intermediate representation)

DWSerialize in memory dispenser operations

DXSerializes tightly coupled distributed transaction branches

FASynchronizes accesses to open ASM files

FBEnsures that only one process can format data blcoks in auto segment space managed tablespaces

FCLGWR opens an ACD thread

FCSMON recovers an ACD thread

FDSynchronization

FESerializes flashback archive recovery

FGonly 1 process in the cluster may do ACD relocation in a disk group

FGresolve race condition to acquire Disk Group Redo Generation Enqueue

FLEnqueue used to synchronize Flashback Database and and deletion of flashback logs.

FLSynchronization

FMSynchronizes access to global file mapping state

FPSynchronizes various File Object (FOB) operations

FRbegin recovery of disk group

FRindicate this ACD thread is alive

FRwait for lock domain detach

FSEnqueue used to synchronize recovery and file operations or synchronize dictionary check

FTallow LGWR to generate redo in this thread

FTprevent LGWR from generating redo in this thread

FUThis enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics

FXARB relocates ACD extent

HDSerializes accesses to ASM SGA data structures

HPSynchronizes accesses to queue pages

HQSynchronizes the creation of new queue IDs

HVLock used to broker the high water mark during parallel inserts

HWLock used to broker the high water mark during parallel inserts

IA

IDLock held to prevent other processes from performing controlfile transaction while NID is running

ILSynchronizes accesses to internal label data structures

IMSerializes block recovery for IMU txn

IRSynchronizes instance recovery

IRSynchronizes parallel instance recovery and shutdown immediate

ISEnqueue used to synchronize instance state changes

ITSynchronizes accesses to a temp object's metadata

JDSynchronizes dates between job queue coordinator and slave processes

JILock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view

JQLock to prevent multiple instances from running a single job

JSLock got during event notification

JSLock got when adding subscriber to event q

JSLock got when doing window open / close

JSLock got when dropping subscriber to event q

JSLock obtained when cleaning up q memory

JSLock on internal scheduler queue

JSLock to prevent job from running elsewhere

JSLock to recover jobs running on crashed RAC inst

JSScheduler evt code and AQ sync

JSScheduler non-global enqueues

JSSynchronizes accesses to the job cache

JXstatement

JXrelease SQL statement resources

KDDetermine DBRM master

KMSynchronizes various Resource Manager operations

KOCoordinates fast object checkpoint

KPSynchronizes kupp process startup

KQSynchronization of ASM cached attributes

KTSynchronizes accesses to the current Resource Manager plan

MDLock held during materialized view log DDL statements

MHLock used for recovery when setting Mail Host for AQ e-mail notifications

MKchanging values in enc $

MLLock used for recovery when setting Mail Port for AQ e-mail notifications

MNSynchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session

MOSerialize MMON operations for restricted sessions

MRLock used to coordinate media recovery with other uses of datafiles

MRLock used to disallow concurrent standby role transition attempt

MSLock held during materialized view refresh to setup MV log

MVHeld during online datafile move operation or cleanup

MWThis enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window

MXLock held to generate a response to the storage server information request when an instance is starting up

OCSynchronizes write accesses to the outline cache

ODLock to prevent concurrent online DDLs

OLSynchronizes accesses to a particular outline name

OQSynchronizes access to olapi history allocation

OQSynchronizes access to olapi history closing

OQSynchronizes access to olapi history flushing

OQSynchronizes access to olapi history globals

OQSynchronizes access to olapi history parameter CB

OTCTX Generic Locks

OWinitializing the wallet context

OWterminate the wallet context

PDPrevents others from updating the same property

PESynchronizes system parameter updates

PFSynchronizes accesses to the password file

PGSynchronizes global system parameter updates

PHLock used for recovery when setting Proxy for AQ HTTP notifications

PICommunicates remote Parallel Execution Server Process creation status

PLCoordinates plug-in operation of transportable tablespaces

PRSynchronizes process startup

PSParallel Execution Server Process reservation and synchronization

PTSynchronizes access to ASM PST metadata

PVSynchronizes instance shutdown_slvstart

PVSynchronizes slave start_shutdown

PWDBWR 0 holds enqueue indicating prewarmed buffers present in cache

PWDirect Load needs to flush prewarmed buffers if DBWR 0 holds enqueue

RBSerializes ASM rollback recovery operations

RCCoordinates access to a result-set

RDupdate RAC load info

RESynchronize block repair / resilvering operations

RFCaptures recent Fast-Start Failover Observer heartbeat information

RFEnsures atomicity of log transport setup

RFEnsures r / w atomicity of DG configuration metadata

RFIdentifies which configuration metadata file is current

RFMeans for detecting when database is being automatically disabled

RFRecords when FSFO Primary Shutdown is suspended

RFSynchronizes apply instance failure detection and failover operation

RFSynchronizes critical apply instance among primary instances

RFSynchronizes selection of the new apply instance

RKwallet master key rekey

RLRAC wallet lock

RNCoordinates nab computations of online logs during recovery

ROCoordinates fast object reuse

ROCoordinates flushing of multiple objects

RPEnqueue held when resilvering is needed or when datablock is repaired from mirror

RRConcurrent invocation of DBMS_WORKLOAD_ * package API

RSLock held to make alert level persistent

RSLock held to prevent aging list update

RSLock held to prevent deleting file to reclaim space

RSLock held to prevent file from accessing during space reclaimation

RSLock held to prevent file from accessing while reusing circular record

RSLock held to read alert level

RSLock held to write alert level

RTThread locks held by CKPT to synchronize thread enable and disable

RTThread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status

RUResults of rolling migration CIC

RUSerializes rolling migration operations

RWLock held by CREATE / ALTER / DROP materialized viewwhile updating materialized view flags in detail tables

RXSynchronizes relocating ASM extents

SBSynchronizes Logical Standby metadata operations

SBSynchronizes table instantiation and EDS operations

SESynchronizes transparent session migration operations

SFLock used for recovery when setting Sender for AQ e-mail notifications

SHShould seldom see this contention as this Enqueue is always acquired in no-wait mode

SIPrevents multiple streams tabel instantiations

SJSerializes cancelling task executed by slave process

SKSerialize shrink of a segment

SLsending lock escalate to LCK0

SLsending lock req for undo to LCK0

SLsending lock req to LCK0

SOSynchronizes access to Shared Object (PL / SQL Shared Object Manager)

SP(1) due to one-off patch

SP(2) due to one-off patch

SP(3) due to one-off patch

SP(4) due to one-off patch

SQLock to ensure that only one process can replenish the sequence cache

SRCoordinates replication / streams operations

SSEnsures that sort segments created during parallel DML operations are not prematurely cleaned up

STSynchronizes space management activities in dictionary-managed tablespaces

SUSerializes access to SaveUndo Segment

SWCoordinates the 'alter system suspend' operation

TASerializes operations on undo segments and undo tablespaces

TBSynchronizes writes to the SQL Tuning Base Existence Cache

TCLock held to guarantee uniqueness of a tablespace checkpoint

TCLock of setup of a unqiue tablespace checkpoint in null mode

TDKTF dumping time / scn mappings in SMON_SCN_TIME table

TEKTF broadcasting

TFSerializes dropping of a temporary file

THSerializes threshold in-memory chain access

TKLock held by MMON to prevent other MMON spawning of Autotask Slave

TKSerializes spawned Autotask Slaves

TLSerializes threshold log table read and update

TMSynchronizes accesses to an object

TOSynchronizes DDL and DML operations on a temp object

TPLock held during purge and dynamic reconfiguration of fixed tables.

TQStreams DDL on queue table

TQTM access to the queue table

TSSerializes accesses to temp segments

TTSerializes DDL operations on tablespaces

TWLock held by one instance to wait for transactions on all instances to finish

TXAllocating an ITL entry in order to begin a transaction

TXLock held by a transaction to allow other transactions to wait for it

TXLock held on a particular row by a transaction to prevent other transactions from modifying it

TXLock held on an index during a split to prevent other operations on it

ULLock used by user applications

USLock held to perform DDL on the undo segment

WALock used for recovery when setting Watermark for memory usage in AQ notifications

WFThis enqueue is used to serialize the flushing of snapshots

WGacquire lobid local enqueue when deleting fso

WGacquire lobid local enqueue when locking fso

WLCoordinates access to redo log files and archive logs

WLSerialize access to RAC-wide SGA

WLSerialize access to RFS global state

WLTesting redo transport access / locking

WMSynchronizes new WLM Plan activation

WPThis enqueue handles concurrency between purging and baselines

WRCoordinates access to logs by Async LNS and ARCH / FG

XCLock obtained when incrementing XDB configuration version number

XDSerialize Auto Drop / Add Exadata disk operations

XDSerialize OFFLINE Exadata disk operations

XDSerialize ONLINE Exadata disk operations

XHLock used for recovery when setting No Proxy Domains for AQ HTTP notifications

XLKeep multiple processes from faulting in the same extent chunk

XQprevent relocation during _recovery_asserts checking

XQwait for recovery before doing relocation

XQwait for relocation before doing block purification

XRLock held during database force logging mode

XRLock held during database quiesce

XYLock used for internal testing

ZAlock held to add partition to std audit table

ZFlock held to add partition to fga audit table

ZGCoordinates file group operations

ZHSynchronizes analysis and insert into compression $, prevents multiple threads analyzing the same table during a load

ZZlock held for updating global context hash tables

Enqueue TypeDescription

enq: AD - allocate AUSynchronizes accesses to a specific OSM disk AU

enq: AD - deallocate AUSynchronizes accesses to a specific OSM disk AU

enq: AF - task serializationThis enqueue is used to serialize access to an advisor task

enq: AG - contentionSynchronizes generation use of a particular workspace

enq: AO - contentionSynchronizes access to objects and scalar variables

enq: AS - contentionSynchronizes new service activation

enq: AT - contentionSerializes 'alter tablespace' operations

enq: AW - AW $ table lockGlobal access synchronization to the AW $ table

enq: AW - AW generation lockIn-use generation state for a particular workspace

enq: AW - user access for AWSynchronizes user accesses to a particular workspace

enq: AW - AW state lockRow lock synchronization for the AW $ table

enq: BR - file shrinkLock held to prevent file from decreasing in physical size during RMAN backup

enq: BR - proxy-copyLock held to allow cleanup from backup mode during an RMAN proxy-copy backup

enq: CF - contentionSynchronizes accesses to the controlfile

enq: CI - contentionCoordinates cross-instance function invocations

enq: CL - drop labelSynchronizes accesses to label cache when dropping a label

enq: CL - compare labelsSynchronizes accesses to label cache for label comparison

enq: CM - gateSerialize access to instance enqueue

enq: CM - instanceIndicate OSM disk group is mounted

enq: CT - global space managementLock held during change tracking space management operations that affect the entire change tracking file

enq: CT - stateLock held while enabling or disabling change tracking, to ensure that it is only enabled or disabled by one user at a time

enq: CT - state change gate 2Lock held while enabling or disabling change tracking in RAC

enq: CT - readingLock held to ensure that change tracking data remains in existence until a reader is done with it

enq: CT - CTWR process start / stopLock held to ensure that only one CTWR process is started in a single instance

enq: CT - state change gate 1Lock held while enabling or disabling change tracking in RAC

enq: CT - change stream ownershipLock held by one instance while change tracking is enabled, to guarantee access to thread-specific resources

enq: CT - local space managementLock held during change tracking space management operations that affect just the data for one thread

enq: CU - contentionRecovers cursors in case of death while compiling

enq: DB - contentionSynchronizes modification of database wide supplemental logging attributes

enq: DD - contentionSynchronizes local accesses to ASM disk groups

enq: DF - contentionEnqueue held by foreground or DBWR when a datafile is brought online in RAC

enq: DG - contentionSynchronizes accesses to ASM disk groups

enq: DL - contentionLock to prevent index DDL during direct load

enq: DM - contentionEnqueue held by foreground or DBWR to synchronize database mount / open with other operations

enq: DN - contentionSerializes group number generations

enq: DP - contentionSynchronizes access to LDAP parameters

enq: DR - contentionSerializes the active distributed recovery operation

enq: DS - contentionPrevents a database suspend during LMON reconfiguration

enq: DT - contentionSerializes changing the default temporary table space and user creation

enq: DV - contentionSynchronizes access to lower-version Diana (PL / SQL intermediate representation)

enq: DX - contentionSerializes tightly coupled distributed transaction branches

enq: FA - access fileSynchronizes accesses to open ASM files

enq: FB - contentionEnsures that only one process can format data blocks in auto segment space managed tablespaces

enq: FC - open an ACD threadLGWR opens an ACD thread

enq: FC - recover an ACD threadSMON recovers an ACD thread

enq: FD - Marker generationSynchronization

enq: FD - Flashback coordinatorSynchronization

enq: FD - Tablespace flashback on / offSynchronization

enq: FD - Flashback on / offSynchronization

enq: FG - serialize ACD relocateOnly 1 process in the cluster may do ACD relocation in a disk group

enq: FG - LGWR redo generation enq raceResolve race condition to acquire Disk Group Redo Generation Enqueue

enq: FG - FG redo generation enq raceResolve race condition to acquire Disk Group Redo Generation Enqueue

enq: FL - Flashback database logSynchronization

enq: FL - Flashback db commandEnqueue used to synchronize Flashback Database and deletion of flashback logs.

enq: FM - contentionSynchronizes access to global file mapping state

enq: FR - contentionBegin recovery of disk group

enq: FS - contentionEnqueue used to synchronize recovery and file operations or synchronize dictionary check

enq: FT - allow LGWR writesAllow LGWR to generate redo in this thread

enq: FT - disable LGWR writesPrevent LGWR from generating redo in this thread

enq: FU - contentionThis enqueue is used to serialize the capture of the DB Feature, Usage and High Water Mark Statistics

enq: HD - contentionSerializes accesses to ASM SGA data structures

enq: HP - contentionSynchronizes accesses to queue pages

enq: HQ - contentionSynchronizes the creation of new queue IDs

enq: HV - contentionLock used to broker the high water mark during parallel inserts

enq: HW - contentionLock used to broker the high water mark during parallel inserts

enq: IA - contention

enq: ID - contentionLock held to prevent other processes from performing controlfile transaction while NID is running

enq: IL - contentionSynchronizes accesses to internal label data structures

enq: IM - contention for blrSerializes block recovery for IMU txn

enq: IR - contentionSynchronizes instance recovery

enq: IR - contention2Synchronizes parallel instance recovery and shutdown immediate

enq: IS - contentionEnqueue used to synchronize instance state changes

enq: IT - contentionSynchronizes accesses to a temp object's metadata

enq: JD - contentionSynchronizes dates between job queue coordinator and slave processes

enq: JI - contentionLock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view

enq: JQ - contentionLock to prevent multiple instances from running a single job

enq: JS - contentionSynchronizes accesses to the job cache

enq: JS - coord post lockLock for coordinator posting

enq: JS - global wdw lockLock acquired when doing wdw ddl

enq: JS - job chain evaluate lockLock when job chain evaluated for steps to create

enq: JS - q mem clnup lckLock obtained when cleaning up q memory

enq: JS - slave enq get lock2Get run info locks before slv objget

enq: JS - slave enq get lock1Slave locks exec pre to sess strt

enq: JS - running job cnt lock3Lock to set running job count epost

enq: JS - running job cnt lock2Lock to set running job count epre

enq: JS - running job cnt lockLock to get running job count

enq: JS - coord rcv lockLock when coord receives msg

enq: JS - queue lockLock on internal scheduler queue

enq: JS - job run lock - synchronizeLock to prevent job from running elsewhere

enq: JS - job recov lockLock to recover jobs running on crashed RAC inst

enq: KK - contextLock held by open redo thread, used by other instances to force a log switch

enq: KM - contentionSynchronizes various Resource Manager operations

enq: KP - contentionSynchronizes kupp process startup

enq: KT - contentionSynchronizes accesses to the current Resource Manager plan

enq: MD - contentionLock held during materialized view log DDL statements

enq: MH - contentionLock used for recovery when setting Mail Host for AQ e-mail notifications

enq: ML - contentionLock used for recovery when setting Mail Port for AQ e-mail notifications

enq: MN - contentionSynchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session

enq: MR - contentionLock used to coordinate media recovery with other uses of datafiles

enq: MS - contentionLock held during materialized view refresh to setup MV log

enq: MW - contentionThis enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window

enq: OC - contentionSynchronizes write accesses to the outline cache

enq: OL - contentionSynchronizes accesses to a particular outline name

enq: OQ - xsoqhiAllocSynchronizes access to olapi history allocation

enq: OQ - xsoqhiCloseSynchronizes access to olapi history closing

enq: OQ - xsoqhistrecbSynchronizes access to olapi history globals

enq: OQ - xsoqhiFlushSynchronizes access to olapi history flushing

enq: OQ - xsoq * histrecbSynchronizes access to olapi history parameter CB

enq: PD - contentionPrevents others from updating the same property

enq: PE - contentionSynchronizes system parameter updates

enq: PF - contentionSynchronizes accesses to the password file

enq: PG - contentionSynchronizes global system parameter updates

enq: PH - contentionLock used for recovery when setting Proxy for AQ HTTP notifications

enq: PI - contentionCommunicates remote Parallel Execution Server Process creation status

enq: PL - contentionCoordinates plug-in operation of transportable tablespaces

enq: PR - contentionSynchronizes process startup

enq: PS - contentionParallel Execution Server Process reservation and synchronization

enq: PT - contentionSynchronizes access to ASM PST metadata

enq: PV - syncstartSynchronizes slave start shutdown

enq: PV - syncshutSynchronizes instance shutdown_slvstart

enq: PW - perwarm status in dbw0DBWR 0 holds enqueue indicating prewarmed buffers present in cache

enq: PW - flush prewarm buffersDirect Load needs to flush pre-warmed buffers if DBWR 0 holds enqueue

enq: RB - contentionSerializes OSM rollback recovery operations

enq: RF - synch: per-SGA Broker metadataEnsures r / w atomicity of DG configuration metadata per unique SGA

enq: RF - synchronization: critical aiSynchronizes critical apply instance among primary instances

enq: RF - new AISynchronizes selection of the new apply instance

enq: RF - synchronization: chiefAnoints 1 instance's DMON as chief to other instances' DMONs

enq: RF - synchronization: HC masterAnoints 1 instance's DMON as health check master

enq: RF - synchronization: aifo masterSynchronizes apply instance failure detection and fail over operation

enq: RF - atomicityEnsures atomicity of log transport setup

enq: RN - contentionCoordinates nab computations of online logs during recovery

enq: RO - contentionCoordinates flushing of multiple objects

enq: RO - fast object reuseCoordinates fast object reuse

enq: RP - contentionEnqueue held when resilvering is needed or when data block is repaired from mirror

enq: RS - file deleteLock held to prevent file from accessing during space reclamation

enq: RS - persist alert levelLock held to make alert level persistent

enq: RS - write alert levelLock held to write alert level

enq: RS - read alert levelLock held to read alert level

enq: RS - prevent aging list updateLock held to prevent aging list update

enq: RS - record reuseLock held to prevent file from accessing while reusing circular record

enq: RS - prevent file deleteLock held to prevent deleting file to reclaim space

enq: RT - contentionThread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status

enq: SB - contentionSynchronizes Logical Standby metadata operations

enq: SF - contentionLock used for recovery when setting Sender for AQ e-mail notifications

enq: SH - contentionShould seldom see this contention as this Enqueue is always acquired in no-wait mode

enq: SI - contentionPrevents multiple streams table instantiations

enq: SK - contentionSerialize shrink of a segment

enq: SQ - contentionLock to ensure that only one process can replenish the sequence cache

enq: SR - contentionCoordinates replication / streams operations

enq: SS - contentionEnsures that sort segments created during parallel DML operations are not prematurely cleaned up

enq: ST - contentionSynchronizes space management activities in dictionary-managed tablespaces

enq: SU - contentionSerializes access to SaveUndo Segment

enq: SW - contentionCoordinates the 'alter system suspend' operation

enq: TA - contentionSerializes operations on undo segments and undo tablespaces

enq: TB - SQL Tuning Base Cache UpdateSynchronizes writes to the SQL Tuning Base Existence Cache

enq: TB - SQL Tuning Base Cache LoadSynchronizes writes to the SQL Tuning Base Existence Cache

enq: TC - contentionLock held to guarantee uniqueness of a tablespace checkpoint

enq: TC - contention2Lock of setup of a unique tablespace checkpoint in null mode

enq: TD - KTF dump entriesKTF dumping time / scn mappings in SMON_SCN_TIME table

enq: TE - KTF broadcastKTF broadcasting

enq: TF - contentionSerializes dropping of a temporary file

enq: TL - contentionSerializes threshold log table read and update

enq: TM - contentionSynchronizes accesses to an object

enq: TO - contentionSynchronizes DDL and DML operations on a temp object

enq: TQ - TM contentionTM access to the queue table

enq: TQ - DDL contentionTM access to the queue table

enq: TQ - INI contentionTM access to the queue table

enq: TS - contentionSerializes accesses to temp segments

enq: TT - contentionSerializes DDL operations on tablespaces

enq: TW - contentionLock held by one instance to wait for transactions on all instances to finish

enq: TX - contentionLock held by a transaction to allow other transactions to wait for it

enq: TX - row lock contentionLock held on a particular row by a transaction to prevent other transactions from modifying it

enq: TX - allocate ITL entryAllocating an ITL entry in order to begin a transaction

enq: TX - index contentionLock held on an index during a split to prevent other operations on it

enq: UL - contentionLock used by user applications

enq: US - contentionLock held to perform DDL on the undo segment

enq: WA - contentionLock used for recovery when setting Watermark for memory usage in AQ notifications

enq: WF - contentionThis enqueue is used to serialize the flushing of snapshots

enq: WL - contentionCoordinates access to redo log files and archive logs

enq: WP - contentionThis enqueue handles concurrency between purging and baselines

enq: XH - contentionLock used for recovery when setting No Proxy Domains for AQ HTTP notifications

enq: XR - quiesce databaseLock held during database quiesce

enq: XR - database force loggingLock held during database force logging mode

enq: XY - contentionLock used for internal testing