仅供自己和各位同学参考：
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 | alter tablespace |
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 | alter database enable block change tracking |
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 |
Enqueue Type | Description |
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 |
