Oracle 10g enqueue waits

October 23rd, 2013
Enqueue Type Description
enq: AD – allocate AU Synchronizes accesses to a specific OSM (Oracle Software Manager) disk AU
enq: AD – deallocate AU Synchronizes accesses to a specific OSM disk AU
enq: AF – task serialization Serializes access to an advisor task
enq: AG – contention Synchronizes generation use of a particular workspace
enq: AO – contention Synchronizes access to objects and scalar variables
enq: AS – contention Synchronizes new service activation
enq: AT – contention Serializes alter tablespace operations
enq: AW – AW$ table lock Allows global access synchronization to the AW$ table (analytical workplace tables used in OLAP option)
enq: AW – AW generation lock Gives in-use generation state for a particular workspace
enq: AW – user access for AW Synchronizes user accesses to a particular workspace
enq: AW – AW state lock Row lock synchronization for the AW$ table
enq: BR – file shrink Lock held to prevent file from decreasing in physical size during RMAN backup
enq: BR – proxy-copy Lock held to allow cleanup from backup mode during an RMAN proxy-copy backup
enq: CF – contention Synchronizes accesses to the controlfile
enq: CI – contention Coordinates cross-instance function invocations
enq: CL – drop label Synchronizes accesses to label cache when dropping a label
enq: CL – compare labels Synchronizes accesses to label cache for label comparison
enq: CM – gate Serializes access to instance enqueue
enq: CM – instance Indicates OSM disk group is mounted
enq: CT – global space management Lock held during change tracking space management operations that affect the entire change tracking file
enq: CT – state Lock held while enabling or disabling change tracking to ensure that it is enabled or disabled by only one user at a time
enq: CT – state change gate 2 Lock held while enabling or disabling change tracking in RAC
enq: CT – reading Lock held to ensure that change tracking data remains in existence until a reader is done with it
enq: CT – CTWR process start/stop Lock held to ensure that only one CTWR (Change Tracking Writer, which tracks block changes and is initiated by the alter database enable block change tracking command) process is started in a single instance
enq: CT – state change gate 1 Lock held while enabling or disabling change tracking in RAC
enq: CT – change stream ownership Lock held by one instance while change tracking is enabled to guarantee access to thread-specific resources
enq: CT – local space management Lock held during change tracking space management operations that affect just the data for one thread
enq: CU – contention Recovers cursors in case of death while compiling
enq: DB – contention Synchronizes modification of database wide supplemental logging attributes
enq: DD – contention Synchronizes local accesses to ASM (Automatic Storage Management) disk groups
enq: DF – contention Enqueue held by foreground or DBWR when a datafile is brought online in RAC
enq: DG – contention Synchronizes accesses to ASM disk groups
enq: DL – contention Lock to prevent index DDL during direct load
enq: DM – contention Enqueue held by foreground or DBWR to synchronize database mount/open with other operations
enq: DN – contention Serializes group number generations
enq: DP – contention Synchronizes access to LDAP parameters
enq: DR – contention Serializes the active distributed recovery operation
enq: DS – contention Prevents a database suspend during LMON reconfiguration
enq: DT – contention Serializes changing the default temporary table space and user creation
enq: DV – contention Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
enq: DX – contention Serializes tightly coupled distributed transaction branches
enq: FA – access file Synchronizes accesses to open ASM files
enq: FB – contention Ensures that only one process can format data blocks in auto segment space managed tablespaces
enq: FC – open an ACD thread LGWR opens an ACD thread
enq: FC – recover an ACD thread SMON recovers an ACD thread
enq: FD – Marker generation Synchronization
enq: FD – Flashback coordinator Synchronization
enq: FD – Tablespace flashback on/off Synchronization
enq: FD – Flashback on/off Synchronization
enq: FG – serialize ACD relocate Only 1 process in the cluster may do ACD relocation in a disk group
enq: FG – LGWR redo generation enq race Resolves race condition to acquire Disk Group Redo Generation Enqueue
enq: FG – FG redo generation enq race Resolves race condition to acquire Disk Group Redo Generation Enqueue
enq: FL – Flashback database log Synchronizes access to Flashback database log
enq: FL – Flashback db command Synchronizes Flashback Database and deletion of flashback logs
enq: FM – contention Synchronizes access to global file mapping state
enq: FR – contention Begins recovery of disk group
enq: FS – contention Synchronizes recovery and file operations or synchronizes dictionary check
enq: FT – allow LGWR writes Allows LGWR to generate redo in this thread
enq: FT – disable LGWR writes Prevents LGWR from generating redo in this thread
enq: FU – contention Serializes the capture of the DB feature, usage, and high watermark statistics
enq: HD – contention Serializes accesses to ASM SGA data structures
enq: HP – contention Synchronizes accesses to queue pages
enq: HQ – contention Synchronizes the creation of new queue IDs
enq: HV – contention Lock used to broker the high watermark during parallel inserts
enq: HW – contention Lock used to broker the high watermark during parallel inserts
enq: IA – contention Information not available
enq: ID – contention Lock held to prevent other processes from performing controlfile transaction while NID is running
enq: IL – contention Synchronizes accesses to internal label data structures
enq: IM – contention for blr Serializes block recovery for IMU txn
enq: IR – contention Synchronizes instance recovery
enq: IR – contention2 Synchronizes parallel instance recovery and shutdown immediate
enq: IS – contention Synchronizes instance state changes
enq: IT – contention Synchronizes accesses to a temp object’s metadata
enq: JD – contention Synchronizes dates between job queue coordinator and slave processes
enq: JI – contention Lock held during materialized view operations (such as refresh, alter) to prevent concurrent operations on the same materialized view
enq: JQ – contention Lock to prevent multiple instances from running a single job
enq: JS – contention Synchronizes accesses to the job cache
enq: JS – coord post lock Lock for coordinator posting
enq: JS – global wdw lock Lock acquired when doing wdw ddl
enq: JS – job chain evaluate lock Lock when job chain evaluated for steps to create
enq: JS – q mem clnup lck Lock obtained when cleaning up q memory
enq: JS – slave enq get lock2 Gets run info locks before slv objget
enq: JS – slave enq get lock1 Slave locks exec pre to sess strt
enq: JS – running job cnt lock3 Lock to set running job count epost
enq: JS – running job cnt lock2 Lock to set running job count epre
enq: JS – running job cnt lock Lock to get running job count
enq: JS – coord rcv lock Lock when coord receives msg
enq: JS – queue lock Lock on internal scheduler queue
enq: JS – job run lock – synchronize Lock to prevent job from running elsewhere
enq: JS – job recov lock Lock to recover jobs running on crashed RAC inst
enq: KK – context Lock held by open redo thread, used by other instances to force a log switch
enq: KM – contention Synchronizes various Resource Manager operations
enq: KP – contention Synchronizes kupp process startup
enq: KT – contention Synchronizes accesses to the current Resource Manager plan
enq: MD – contention Lock held during materialized view log DDL statements
enq: MH – contention Lock used for recovery when setting Mail Host for AQ e-mail notifications
enq: ML – contention Lock used for recovery when setting Mail Port for AQ e-mail notifications
enq: MN – contention Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
enq: MR – contention Lock used to coordinate media recovery with other uses of datafiles
enq: MS – contention Lock held during materialized view refresh to set up MV log
enq: MW – contention Serializes the calibration of the manageability schedules with the Maintenance Window
enq: OC – contention Synchronizes write accesses to the outline cache
enq: OL – contention Synchronizes accesses to a particular outline name
enq: OQ – xsoqhiAlloc Synchronizes access to olapi history allocation
enq: OQ – xsoqhiClose Synchronizes access to olapi history closing
enq: OQ – xsoqhistrecb Synchronizes access to olapi history globals
enq: OQ – xsoqhiFlush Synchronizes access to olapi history flushing
enq: OQ – xsoq*histrecb Synchronizes access to olapi history parameter CB
enq: PD – contention Prevents others from updating the same property
enq: PE – contention Synchronizes system parameter updates
enq: PF – contention Synchronizes accesses to the password file
enq: PG – contention Synchronizes global system parameter updates
enq: PH – contention Lock used for recovery when setting proxy for AQ HTTP notifications
enq: PI – contention Communicates remote Parallel Execution Server Process creation status
enq: PL – contention Coordinates plug-in operation of transportable tablespaces
enq: PR – contention Synchronizes process startup
enq: PS – contention Parallel Execution Server Process reservation and synchronization
enq: PT – contention Synchronizes access to ASM PST metadata
enq: PV – syncstart Synchronizes slave start_shutdown
enq: PV – syncshut Synchronizes instance shutdown_slvstart
enq: PW – prewarm status in dbw0 DBWR0 holds this enqueue indicating pre-warmed buffers present in cache
enq: PW – flush prewarm buffers Direct Load needs to flush prewarmed buffers if DBWR0 holds this enqueue
enq: RB – contention Serializes OSM rollback recovery operations
enq: RF – synch: per-SGA Broker metadata Ensures r/w atomicity of DG configuration metadata per unique SGA
enq: RF – synchronization: critical ai Synchronizes critical apply instance among primary instances
enq: RF – new AI Synchronizes selection of the new apply instance
enq: RF – synchronization: chief Anoints 1 instance’s DMON (Data Guard Broker Monitor) as chief to other instance’s DMONs
enq: RF – synchronization: HC master Anoints 1 instance’s DMON as health check master
enq: RF – synchronization: aifo master Synchronizes critical apply instance failure detection and failover operation
enq: RF – atomicity Ensures atomicity of log transport setup
enq: RN – contention Coordinates nab computations of online logs during recovery
enq: RO – contention Coordinates flushing of multiple objects
enq: RO – fast object reuse Coordinates fast object reuse
enq: RP – contention Enqueue held when resilvering is needed or when data block is repaired from mirror
enq: RS – file delete Lock held to prevent file from accessing during space reclamation
enq: RS – persist alert level Lock held to make alert level persistent
enq: RS – write alert level Lock held to write alert level
enq: RS – read alert level Lock held to read alert level
enq: RS – prevent aging list update Lock held to prevent aging list update
enq: RS – record reuse Lock held to prevent file from accessing while reusing circular record
enq: RS – prevent file delete Lock held to prevent deleting file to reclaim space
enq: RT – contention Thread locks held by LGWR, DBW0, and RVWR (Recovery Writer, used in Flashback Database operations) to indicate mounted or open status
enq: SB – contention Synchronizes logical standby metadata operations
enq: SF – contention Lock held for recovery when setting sender for AQ e-mail notifications
enq: SH – contention Enqueue always acquired in no-wait mode – should seldom see this contention
enq: SI – contention Prevents multiple streams table instantiations
enq: SK – contention Serialize shrink of a segment
enq: SQ – contention Lock to ensure that only one process can replenish the sequence cache
enq: SR – contention Coordinates replication / streams operations
enq: SS – contention Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
enq: ST – contention Synchronizes space management activities in dictionary-managed tablespaces
enq: SU – contention Serializes access to SaveUndo Segment
enq: SW – contention Coordinates the ‘alter system suspend’ operation
enq: TA – contention Serializes operations on undo segments and undo tablespaces
enq: TB – SQL Tuning Base Cache Update Synchronizes writes to the SQL Tuning Base Existence Cache
enq: TB – SQL Tuning Base Cache Load Synchronizes writes to the SQL Tuning Base Existence Cache
enq: TC – contention Lock held to guarantee uniqueness of a tablespace checkpoint
enq: TC – contention2 Lock during setup of a unique tablespace checkpoint in null mode
enq: TD – KTF dump entries KTF dumping time/scn mappings in SMON_SCN_TIME table
enq: TE – KTF broadcast KTF broadcasting
enq: TF – contention Serializes dropping of a temporary file
enq: TL – contention Serializes threshold log table read and update
enq: TM – contention Synchronizes accesses to an object
enq: TO – contention Synchronizes DDL and DML operations on a temp object
enq: TQ – TM contention TM access to the queue table
enq: TQ – DDL contention DDL access to the queue table
enq: TQ – INI contention TM access to the queue table
enq: TS – contention Serializes accesses to temp segments
enq: TT – contention Serializes DDL operations on tablespaces
enq: TW – contention Lock held by one instance to wait for transactions on all instances to finish
enq: TX – contention Lock held by a transaction to allow other transactions to wait for it
enq: TX – row lock contention Lock held on a particular row by a transaction to prevent other transactions from modifying it
enq: TX – allocate ITL entry Allocating an ITL entry in order to begin a transaction
enq: TX – index contention Lock held on an index during a split to prevent other operations on it
enq: UL – contention Lock held used by user applications
enq: US – contention Lock held to perform DDL on the undo segment
enq: WA – contention Lock used for recovery when setting watermark for memory usage in AQ notifications
enq: WF – contention Enqueue used to serialize the flushing of snapshots
enq: WL – contention Coordinates access to redo log files and archive logs
enq: WP – contention Enqueue to handle concurrency between purging and baselines
enq: XH – contention Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
enq: XR – quiesce database Lock held during database quiesce
enq: XR – database force logging Lock held during database force logging mode
enq: XY – contention Lock used by Oracle Corporation for internal testing
  Events parameters
NAME PARAMETER1 PARAMETER2 PARAMETER3
enq: AD – allocate AU name|mode group and disk number AU number
enq: AD – deallocate AU name|mode group and disk number AU number
enq: AF – task serialization name|mode task id 0
enq: AG – contention name|mode workspace # generation
enq: AM – client registration name|mode id1 id2
enq: AM – rollback COD reservation name|mode id1 id2
enq: AM – shutdown name|mode id1 id2
enq: AO – contention name|mode workspace # object #
enq: AS – modify service name|mode 0 0
enq: AS – service activation name|mode 0 0
enq: AT – contention name|mode 0 0
enq: AU – audit index file name|mode XML audit index file 0
enq: AW – AW generation lock name|mode operation workspace #
enq: AW – AW state lock name|mode operation workspace #
enq: AW – AW$ table lock name|mode operation workspace #
enq: AW – user access for AW name|mode operation workspace #
enq: BF – PMON Join Filter cleanup name|mode node#/parallelizer# bloom#
enq: BF – allocation contention name|mode node#/parallelizer# bloom#
enq: BR – file shrink name|mode operation file #
enq: BR – proxy-copy name|mode operation file #
enq: CF – contention name|mode 0 operation
enq: CI – contention name|mode opcode type
enq: CL – compare labels name|mode object # 0
enq: CL – drop label name|mode object # 0
enq: CM – gate name|mode disk group # type
enq: CM – instance name|mode disk group # type
enq: CN – race with init name|mode reg id 0
enq: CN – race with reg name|mode reg id 0
enq: CN – race with txn name|mode reg id 0
enq: CT – CTWR process start/stop name|mode operation operation parm
enq: CT – change stream ownership name|mode operation operation parm
enq: CT – global space management name|mode operation operation parm
enq: CT – local space management name|mode operation operation parm
enq: CT – reading name|mode operation operation parm
enq: CT – state name|mode operation operation parm
enq: CT – state change gate 1 name|mode operation operation parm
enq: CT – state change gate 2 name|mode operation operation parm
enq: CU – contention name|mode handle handle
enq: DB – contention name|mode EnqMode 0
enq: DD – contention name|mode disk group type
enq: DF – contention name|mode 0 file #
enq: DG – contention name|mode disk group type
enq: DL – contention name|mode object # 0
enq: DM – contention name|mode type type
enq: DN – contention name|mode 0 0
enq: DP – contention name|mode 0 0
enq: DR – contention name|mode 0 0
enq: DS – contention name|mode 0 0
enq: DT – contention name|mode 0 0
enq: DV – contention name|mode object # 0
enq: DX – contention name|mode transaction entry # 0
enq: FA – access file name|mode disk group number file number
enq: FB – contention name|mode tablespace # dba
enq: FC – open an ACD thread name|mode disk group thread
enq: FC – recover an ACD thread name|mode disk group thread
enq: FD – Flashback coordinator name|mode Internal Internal
enq: FD – Flashback on/off name|mode Internal Internal
enq: FD – Marker generation name|mode Internal Internal
enq: FD – Restore point create/drop name|mode Internal Internal
enq: FD – Tablespace flashback on/off name|mode Internal Internal
enq: FG – FG redo generation enq race name|mode disk group type
enq: FG – LGWR redo generation enq race name|mode disk group type
enq: FG – serialize ACD relocate name|mode disk group type
enq: FL – Flashback database log name|mode Log # zero
enq: FL – Flashback db command name|mode Log # zero
enq: FM – contention name|mode 0 0
enq: FP – global fob contention name|mode low file obj add high file obj add
enq: FR – contention name|mode disk group unused
enq: FS – contention name|mode 0 type
enq: FT – allow LGWR writes name|mode disk group thread
enq: FT – disable LGWR writes name|mode disk group thread
enq: FU – contention name|mode 0 0
enq: HD – contention name|mode disk group 0
enq: HP – contention name|mode tablespace # dba
enq: HQ – contention name|mode object # hash value
enq: HV – contention name|mode object # 0
enq: HW – contention name|mode table space # block
enq: IA – contention name|mode 0 0
enq: ID – contention name|mode 0 0
enq: IL – contention name|mode object # 0
enq: IM – contention for blr name|mode pool # 0
enq: IR – contention name|mode 0 0/1
enq: IR – contention2 name|mode 0 0/1
enq: IS – contention name|mode 0 type
enq: IT – contention name|mode object # 0
enq: JD – contention name|mode 0 0
enq: JI – contention name|mode view object # 0
enq: JQ – contention name|mode 0 0
enq: JS – contention name|mode service ID queue type
enq: JS – evt notify name|mode service ID queue type
enq: JS – evtsub add name|mode service ID queue type
enq: JS – evtsub drop name|mode service ID queue type
enq: JS – job recov lock name|mode service ID queue type
enq: JS – job run lock – synchronize name|mode service ID queue type
enq: JS – q mem clnup lck name|mode service ID queue type
enq: JS – queue lock name|mode service ID queue type
enq: JS – sch locl enqs name|mode service ID queue type
enq: JS – wdw op name|mode service ID queue type
enq: KK – context name|mode 0 redo thread
enq: KM – contention name|mode type type
enq: KO – fast object checkpoint name|mode 2 0
enq: KP – contention name|mode 0 0
enq: KT – contention name|mode plan # 0
enq: MD – contention name|mode master object # 0
enq: MH – contention name|mode 0 0
enq: MK – contention name|mode 0 0
enq: ML – contention name|mode 0 0
enq: MN – contention name|mode session ID 0
enq: MO – contention name|mode 0 0
enq: MR – contention name|mode 0 or file # type
enq: MS – contention name|mode master object # 0
enq: MW – contention name|mode Schedule Id 0
enq: OC – contention name|mode 1 2
enq: OL – contention name|mode hash value 0
enq: OQ – xsoq*histrecb name|mode resource id 0
enq: OQ – xsoqhiAlloc name|mode resource id 0
enq: OQ – xsoqhiClose name|mode resource id 0
enq: OQ – xsoqhiFlush name|mode resource id 0
enq: OQ – xsoqhistrecb name|mode resource id 0
enq: OW – initialization name|mode 0 0
enq: OW – termination name|mode 0 0
enq: PD – contention name|mode property name key hash
enq: PE – contention name|mode parno 0
enq: PF – contention name|mode 0 0
enq: PG – contention name|mode 0 0
enq: PH – contention name|mode 0 0
enq: PI – contention name|mode operation serial #
enq: PL – contention name|mode 0 0
enq: PR – contention name|mode 0 0
enq: PS – contention name|mode instance slave ID
enq: PT – contention name|mode disk group # type
enq: PV – syncshut name|mode 0 0
enq: PV – syncstart name|mode 0 0
enq: PW – flush prewarm buffers name|mode 0 0
enq: PW – perwarm status in dbw0 name|mode 0 0
enq: RB – contention name|mode disk group 0
enq: RF – RF – Database Automatic Disable name|mode lock operation lock value
enq: RF – RF – FSFO Observed name|mode lock operation lock value
enq: RF – RF – FSFO connectivity name|mode lock operation lock value
enq: RF – RF – FSFO state name|mode lock operation lock value
enq: RF – RF – FSFO synchronization name|mode lock operation lock value
enq: RF – RF – FSFO wait name|mode lock operation lock value
enq: RF – atomicity name|mode lock operation lock value
enq: RF – new AI name|mode lock operation lock value
enq: RF – synch: DG Broker metadata name|mode lock operation lock value
enq: RF – synchronization: HC master name|mode lock operation lock value
enq: RF – synchronization: aifo master name|mode lock operation lock value
enq: RF – synchronization: chief name|mode lock operation lock value
enq: RF – synchronization: critical ai name|mode lock operation lock value
enq: RN – contention name|mode thread number log number
enq: RO – contention name|mode 2 0
enq: RO – fast object reuse name|mode 2 0
enq: RP – contention name|mode file # 1 or block
enq: RR – contention name|mode lock# not used
enq: RS – file delete name|mode record type record id
enq: RS – persist alert level name|mode record type record id
enq: RS – prevent aging list update name|mode record type record id
enq: RS – prevent file delete name|mode record type record id
enq: RS – read alert level name|mode record type record id
enq: RS – record reuse name|mode record type record id
enq: RS – write alert level name|mode record type record id
enq: RT – contention name|mode redo thread type
enq: RU – contention name|mode 0 0
enq: RU – waiting name|mode 0 0
enq: RW – MV metadata contention name|mode table obj# 0
enq: SB – contention name|mode 0 0
enq: SE – contention name|mode Session-id Serial#
enq: SF – contention name|mode 0 0
enq: SH – contention name|mode 0 0
enq: SI – contention name|mode object # 0
enq: SK – contention name|mode tablespace # dba
enq: SQ – contention name|mode object # 0
enq: SR – contention name|mode operation sequence # / apply #
enq: SS – contention name|mode tablespace # dba
enq: ST – contention name|mode 0 0
enq: SU – contention name|mode table space # 0
enq: SW – contention name|mode 0 0
enq: TA – contention name|mode operation undo segment # / other
enq: TB – SQL Tuning Base Cache Load name|mode 1 2
enq: TB – SQL Tuning Base Cache Update name|mode 1 2
enq: TC – contention name|mode checkpoint ID 0
enq: TC – contention2 name|mode checkpoint ID 0
enq: TD – KTF dump entries name|mode 0 0
enq: TE – KTF broadcast name|mode 0 0
enq: TF – contention name|mode tablespace # relative file #
enq: TL – contention name|mode 0 0
enq: TM – contention name|mode object # table/partition
enq: TO – contention name|mode object # 1
enq: TQ – DDL contention name|mode QT_OBJ# 0
enq: TQ – INI contention name|mode QT_OBJ# 0
enq: TQ – TM contention name|mode QT_OBJ# 0
enq: TS – contention name|mode tablespace ID dba
enq: TT – contention name|mode tablespace ID operation
enq: TW – contention name|mode 0 operation
enq: TX – allocate ITL entry name|mode usn<<16 | slot sequence
enq: TX – contention name|mode usn<<16 | slot sequence
enq: TX – index contention name|mode usn<<16 | slot sequence
enq: TX – row lock contention name|mode usn<<16 | slot sequence
enq: UL – contention name|mode id 0
enq: US – contention name|mode undo segment # 0
enq: WA – contention name|mode 0 0
enq: WF – contention name|mode 0 0
enq: WL – contention name|mode log # / thread id # sequence #
enq: WP – contention name|mode 0 0
enq: WR – contention name|mode thread id # sequence #
enq: XH – contention name|mode 0 0
enq: XQ – recovery name|mode disk group # unused
enq: XQ – relocation name|mode disk group # unused
enq: XR – database force logging name|mode operation 0
enq: XR – quiesce database name|mode operation 0
enq: XY – contention name|mode id1 id2
enq: ZG – contention name|mode file group id version id
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