Oracle Database lock types

Oracle Database has a very sophisticated locking mechanism built-in. Locks are used to prevent destructive interactions within the database. Interactions are destructive when they incorrectly update data or incorrectly alter underlying data structures, between transactions accessing shared data. Locks play a crucial role in maintaining database concurrency, consistency, and integrity.

The Oracle database has over 200 different lock types which are grouped into three categories:

  1. DML Locks
    DML locks protect data. They guarantee the integrity of data accessed concurrently by multiple users. For example, table locks and row locks.
  2. DDL Locks
    DDL locks protect the definition of schema objects while ongoing DDL operations acts on or refer to the objects. For example, the dictionary definitions of tables and views.
  3. System Locks
    System locks are used to protect internal database and memory structures. These mechanisms are inaccessible to users and they have no control over their occurrence or duration. System locks are entirely automatic.

Below you can find all the different lock types, their names and description in a given database version. The column IS_USER indicates whether the lock is acquired as a direct result of a SQL statement, or produced automatically by the database itself.

Oracle 19c lock types
Oracle 18c lock types
Oracle 12c R2 lock types
Oracle 12c R1 lock types
Oracle 11g R2 lock types
Oracle 11g R1 lock types
Oracle 10g R2 lock types
Oracle 10g R1 lock types

Oracle 19c lock types

Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 – Production
Version 19.3.0.0.0

Total: 291

TYPE NAME IS_USER DESCRIPTION
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
ZH Compression Analyzer YES Synchronizes analysis and insert into compression$, prevents multiple threads analyzing the same table during a load
AB Auto BMR NO A general class of locks used by auto BMR for various purposes
AC Application Continuity NO Synchronizes new service activation
AD ASM Disk AU Lock NO Synchronizes accesses to a specific ASM disk AU
AE Edition Lock NO Prevent Dropping an edition in use
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AH ASM Relocation Lock High NO Protects locked extent pointers during ASM file relocation
AK GES Deadlock Test NO Lock used for internal testing
AM ASM Enqueue NO ASM instance general-purpose enqueue
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AP SPM Autopurge NO This enqueue is used to serialize the purging of SQL plan baselines
AQ Queue Partitioning local enqueue NO Synchronizes partition operations on queue table within instance
AR ASM Relocation Lock NO Protects locked extent pointers during ASM file relocation
AS Service Operations NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AU DBKR NO This enqueue is used to serialize ADR purge operation
AV ASM volume locks NO id1 is for persistent DG number locking. id2 is for other volume serialization
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
AY KSXA Test Affinity Dictionary NO Affinity Dictionary test affinity synchronization
AZ Emon-SRVNTFN_Q Create NO Synchronize creation of AQ_SRVNTFN_Q among emon slaves
BA non durable sub bmap alloc NO Synchronizes access to globl Bitmap Alloc
BB Global Transaction Branch NO 2PC distributed transaction branch across RAC instances
BC BA Container NO Backup Appliance Container
BE Critical Block Allocation NO Lock used to serialize allocation of critical blocks
BF BLOOM FILTER NO Synchronize access to a bloom filter in a parallel statement
BI BA Contained File Identification NO Backup Appliance Contained File Identification
BM clonedb bitmap file access NO synchronizes clonedb bitmap file operations
BO DRM Banned-Object List NO Coordinates dynamic remastering banned-object list
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
BS Backup/Restore spare enq NO KRB space usage
BU Buddy Instance Context NO synchronizes access to Recovery Set constructed by RMS0
BV BA Group Rebuild/Validate NO Backup Appliance Container Rebuild/Validate
BZ BA Contained File Resize NO Backup Appliance Contained File Resize
CA Calibration NO Lock used by IO Calibration
CB CBAC Master Lock NO Synchronizes accesses to the CBAC roles cached in KGL
CC Column Key NO Serializes Column Encryption Key Cache
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM ASM Instance Enqueue NO ASM instance and gate enqueue
CN KTCN REG enq NO Enqueue held for registrations for change notifications
CO KTUCLO Master Slave enq NO Enqueue held for determining Master Slaves
CP Pluggable Database NO Coordinate pluggable database operations
CQ Cleanup querycache registrations NO Serializes access to cleanup client query cache registrations
CR Reuse Block Range NO Coordinates checkpointing of block range reuse
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
CX TEXT: Index Specific Lock NO Index Specific Lock on CTX index
DA Instance DP Array NO Slave Process Spawn reservation and synchronization
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DE Planned Draining RAC enqueue NO Enqueue to serialize draining structure updates
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open or pluggable database open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DO ASM Disk Online Lock NO Synchronizes disk onlines and their recovery
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DW In memory Dispenser NO Serialize in memory dispenser operations
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FE KTFA Recovery NO Flashback archive Enqueue to serialize recovery
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FH Flush Stat NO Serializes flush of ILM stats to disk
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FO Oracle File System Operation NO Synchronize Oracle File System Operations
FP File Object NO Synchronizes various File Object(FOB) operations
FR Disk Group Recovery NO enqueue to control ASM recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
FW Flashback Writer NO Coordinate RVWR on multiple instances
FX ACD Xtnt Info CIC NO serialize ACD relocation CIC
FZ ASM Freezing Cache Lock NO Freezes ASM Cache for a diskgroup
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HC HSM cache NO Add or Remove from HSM cache
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HM Hang Manager Test Resource NO Resource to Generate Hangs for Hang Manager Testing
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
IC IOServer Client NO Gets a unique client ID
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IF IOServer File NO Synchronizes file operations
II IOS Instance fencing lock NO Signals fencing of a client in an instance
IK IOS instance node fencing NO Signals cluster/node fencing status
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IN in-memory segment NO Serialize in-memory segment create/drop
IP PDB Instance State NO Enqueue used to synchronize instance state changes for PDBs
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JG Job Scheduler1 NO Synchronizes accesses to the job cache1
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
JX SQL STATEMENT QUEUE NO synchronize SQL statement queue operations
JZ Join group dictionary NO Synchronizes modifications to im_domain$ and im_joingroup$
KA Kernel Service ACL NO Global ACL State (Disabled=0/Enabled=1
KD Scheduler Master DBRM NO Determine DBRM master
KE ASM Cached Attributes NO Synchronization of ASM cached attributes
KI KJCI Serialization Enqueue NO Enqueue to Serialize KJCI Cross-Instance Calls
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KL LOB KSI LOCK NO KSI lock for buffer cache and wgc concurrency
KM Scheduler NO Synchronizes various Resource Manager operations
KO Multiple Object Checkpoint NO Coordinates checkpointing of multiple objects
KP Kupp Process Startup NO Synchronizes kupp process startup
KQ ASM Attributes Enque NO Single Inst Sync of ASM attributes
KR Enqueue-Delete Rule NO Synchronize delete rule and add rule to ruleset
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
KV KEY VECTOR NO Synchronizes access to a key vector in an IMA query
KZ ASM:Purge Audit NO Coordinate GEN0 on multiple instances
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MC SGA Log Operation NO Lock held during dml/ddl for a securefile log
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MF SGA Log-Bkt Flush NO Lock held during flushing a log bucket
MG MGA service NO synchronize MGA service
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
MK Master Key NO Serializes enc$ access
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MM MMON Management NO MMON AutoTask Management
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MO MMON restricted session NO Serialize MMON operations for restricted sessions
MP SGA Log Partition NO Lock held during partitioning an instance log
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MV Online Datafile Move NO Synchronizes online datafile move operation or cleanup
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
MX ksz synch NO Used to synchronize storage server info across all nodes
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OD Online DDLs NO Lock to prevent concurrent online DDLs
OE DLM Enqueue Owner Serialization NO Enqueue to serialize access to an Omni Enqueue Owner
OL Outline Name NO Synchronizes accesses to a particular outline name
OP Label Security Profile NO Synchronizes access to the ols$profile table
OQ OLAPI Histories NO Synchronizes access to olapi history resources
OT TEXT: Generic Lock NO Generic Lock on CTX index
OW Encryption Wallet NO Serializes wallet initialization and access
PA Privilege Capture API NO Lock held for modifying or reading a privilege capture
PB PDB DDL Operations NO Enqueue used to synchronize PDB DDL operations
PC Enqueue for kzppctxs NO Lock used for accesing kzppctx in SGA
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PJ DV Policy Admin API NO Lock held for Database Vault policy administration API
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PP GES Plug and Play Enqueue NO Coordinates Adding Plug and Play Instances
PQ Queue Ptning global enq NO Synchronizes partitioning operations on queue table accross instances
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
PW Buffer Cache PreWarm NO Coordinates Direct Loads with Prewarmed cache buffers
PX PDB Recovery Operations NO Enqueue used to synchronize recovery-related PDB operations
PZ Password File Metadata Cache NO Synchronizes changes to the password file metadata cache
Q Row Cache NO Coordinates updates and accesses to row cache objects
RA Real-Time ADDM Flood Control NO Coordinate Flood Control in RAC
RB ASM Rollback Recovery NO Serializes ASM rollback recovery operations
RC Result Cache: Enqueue NO Accessing a result in the result-set cache
RD RAC Load NO synchronize update of RAC load info
RE Block Repair/Resilvering NO Synchronizes block repair/mirror resilvering operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RG Replication Global NO Coordinates instance-wide replication / streams operations
RH SQLQ Autopurge NO This enqueue is used to serialize the purging of SQL quarantine configurations
RI Reader Farm SQL Isolation NO Reader Farm SQL Isolation
RK wallet_set_mkey NO Serializes wallet master key rekey
RL RAC Encryption Wallet Lock NO RAC encryption wallet lock
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RQ Enqueue-Cross SCN NO Synchronize enqueue-dequeue-cross on SCN generation
RR Workload Capture and Replay NO Prevents concurrent invokers of DBMS_WORKLOAD_*
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
RU Rolling Migration NO Serilized rolling migration operations
RW Materialized View Flags NO Lock used when creating or readingmaterialized view flags in detail tables
RX ASM Extent Relocation Lock NO Synchronizes relocating ASM extents
RZ RFS Logminer FLC NO Synchronizes updates to logminer foreign log cache
SA Purge SRL NO Coordinates access to SRL by RFS and recovery process
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SE Session Migration NO Lock used by transparent session migration
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SG OLS groups NO Synchronizes access to ols$groups table
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SJ KTSJ Slave Task Cancel NO Serializes cancelling task executed by slave process
SK Shrink Segment NO Serialize shrink of a segment
SL Serialize Lock request NO Request serialization to LCK0
SM SMON Serialization NO Lock to check SMON global work in RAC
SN PDB SGA ALLOCATION NO Synchronize PDB SGA Allocation
SO Shared Object NO Synchronizes access to Shared Object(PL/SQL Shared Object Manager)
SP Spare Enqueue 0 NO Spare enqueue 0 for one-off backports
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
SX Spare Enqueue 1 NO Spare enqueue 1 for one-off backports
SY IM chunk populate NO Lock used to serialize in-memory chunk populates
SZ IM segment populate NO Lock used to serialize in-memory segment populates
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TG In Memory Temp Object NO access to imcdt global resource
TH Threshold Chain NO Serializes threshold in-memory chain access
TI In Memory Temp Object HT NO access to an imcdt object HT
TK Auto Task Serialization NO Prevents more than one AutoTask Background Slave from being spawned
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TP Runtime Fixed Table Purge NO Lock used for fixed runtime table purge and definition
TQ Queue table enqueue NO Synchronizes access to queue table
TR Tablespace Rekey NO Coordinates tablespace rekey
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TU TOP UPD NO Enqueue to serialize updates to topology data
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
TZ in-memory NO Serialize in-memory area create/drop
UF AWR undostat stat flush for PDB NO This enqueue is used to serialize undo stat flush per PDB
US Undo Segment NO Lock held to perform DDL on the undo segment
UT Transfer Unified Audit Records NO Lock held for transfer of unified audit records
V Library Cache Lock 3 NO Synchronizes accesses to library cache objects
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WD AWR mail package retrieval NO Serialize retrieving AWR mail package
WE AWR auto-export NO Serialize auto-export of AWR data
WF AWR Flush NO This enqueue is used to serialize the flushing of snapshots
WG Write gather local enqueue NO Long term lock on wgc file state
WI AWR import NO Serialize the import of AWR dump files
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WM WLM Plan Operations NO Synchronizes new WLM Plan activation
WN read_write_snapshot NO Synchronizes read write snapshot creation
WP AWR Purge NO This enqueue handles concurrency between purging and baselines
WR LNS archiving log NO Coordinates access to logs by Async LNS and ARCH/FG
WS Logwriter member NO Used by Logwriter to coordinate communication to databases
WT AWR CDB-Wide Table Lock NO This enqueue serializes CDB-Wide Operation on AWR Table
XB ASM Group Block lock NO Prevents client diskgroup use during storage reconfiguration
XC XDB Configuration NO Synchronization access to XDB configuration
XD Auto Online Exadata disks NO Serialize Auto Management of Exadata disks
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XK GES Test-Lock for KSIRESTXDV NO Lock used for internal testing
XL ASM Extent Fault Lock NO Keep multiple processes from faulting in the same extent chunk
XM RM Master Lock NO RMON which process this lock is the Master
XQ ASM Extent Relocation Enqueue NO ASM extent relocation
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing
Y Library Cache Pin 3 NO Synchronizes accesses to the contents of library cache objects
ZA Audit Partition NO Lock held for adding partition to Aud table
ZB in-memory TS NO Serialize in-memory tablespace create/drop
ZC IM FastStart Admin NO Lock used to serialize in-memory FS tasks
ZD IM FastStart CU NO Lock used to serialize in-memory FS CU
ZF FGA Partition NO Lock held for adding partition to Fga table
ZG File Group NO Coordinates file group operations
ZL Foreign Log Maintenance NO Synchronizes updates to foreign log metadata by LogMiner reader and RFS processes
ZP Private Temp Table synchronize NO Synchronizes add/remove/read of PTT-GTT mapping
ZQ quiesce enq NO Serialize SMU create and load quiesce
ZR ZDLRA Server NO Lock held by a recovery server operation to allow other operations to wait for it
ZS Spillover Audit files NO Lock held for exclusive access on a Spillover audit file
ZX repopulation file access NO synchronizes file operations during repopulation
ZZ Global Context Action NO Lock held for updating Global context hash tables

Top

Oracle 18c lock types

Oracle Database 18c Enterprise Edition Release 18.0.0.0.0 – Production
Version 18.3.0.0.0

Total: 285

TYPE NAME IS_USER DESCRIPTION
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
ZH Compression Analyzer YES Synchronizes analysis and insert into compression$, prevents multiple threads analyzing the same table during a load
AB Auto BMR NO A general class of locks used by auto BMR for various purposes
AC Application Continuity NO Synchronizes new service activation
AD ASM Disk AU Lock NO Synchronizes accesses to a specific ASM disk AU
AE Edition Lock NO Prevent Dropping an edition in use
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AH ASM Relocation Lock High NO Protects locked extent pointers during ASM file relocation
AK GES Deadlock Test NO Lock used for internal testing
AM ASM Enqueue NO ASM instance general-purpose enqueue
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AP SPM Autopurge NO This enqueue is used to serialize the purging of SQL plan baselines
AQ Queue Partitioning local enqueue NO Synchronizes partition operations on queue table within instance
AR ASM Relocation Lock NO Protects locked extent pointers during ASM file relocation
AS Service Operations NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AU DBKR NO This enqueue is used to serialize ADR purge operation
AV ASM volume locks NO id1 is for persistent DG number locking. id2 is for other volume serialization
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
AY KSXA Test Affinity Dictionary NO Affinity Dictionary test affinity synchronization
AZ Emon-SRVNTFN_Q Create NO Synchronize creation of AQ_SRVNTFN_Q among emon slaves
BA non durable sub bmap alloc NO Synchronizes access to globl Bitmap Alloc
BB Global Transaction Branch NO 2PC distributed transaction branch across RAC instances
BC BA Container NO Backup Appliance Container
BE Critical Block Allocation NO Lock used to serialize allocation of critical blocks
BF BLOOM FILTER NO Synchronize access to a bloom filter in a parallel statement
BI BA Contained File Identification NO Backup Appliance Contained File Identification
BM clonedb bitmap file access NO synchronizes clonedb bitmap file operations
BO DRM Banned-Object List NO Coordinates dynamic remastering banned-object list
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
BS Backup/Restore spare enq NO KRB space usage
BU Buddy Instance Context NO synchronizes access to Recovery Set constructed by RMS0
BV BA Group Rebuild/Validate NO Backup Appliance Container Rebuild/Validate
BZ BA Contained File Resize NO Backup Appliance Contained File Resize
CA Calibration NO Lock used by IO Calibration
CB CBAC Master Lock NO Synchronizes accesses to the CBAC roles cached in KGL
CC Column Key NO Serializes Column Encryption Key Cache
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM ASM Instance Enqueue NO ASM instance and gate enqueue
CN KTCN REG enq NO Enqueue held for registrations for change notifications
CO KTUCLO Master Slave enq NO Enqueue held for determining Master Slaves
CP Pluggable Database NO Coordinate pluggable database operations
CQ Cleanup querycache registrations NO Serializes access to cleanup client query cache registrations
CR Reuse Block Range NO Coordinates checkpointing of block range reuse
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
CX TEXT: Index Specific Lock NO Index Specific Lock on CTX index
DA Instance DP Array NO Slave Process Spawn reservation and synchronization
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DE Planned Draining RAC enqueue NO Enqueue to serialize draining structure updates
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open or pluggable database open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DO ASM Disk Online Lock NO Synchronizes disk onlines and their recovery
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DW In memory Dispenser NO Serialize in memory dispenser operations
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FE KTFA Recovery NO Flashback archive Enqueue to serialize recovery
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FH Flush Stat NO Serializes flush of ILM stats to disk
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FO Oracle File System Operation NO Synchronize Oracle File System Operations
FP File Object NO Synchronizes various File Object(FOB) operations
FR Disk Group Recovery NO enqueue to control ASM recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
FW Flashback Writer NO Coordinate RVWR on multiple instances
FX ACD Xtnt Info CIC NO serialize ACD relocation CIC
FZ ASM Freezing Cache Lock NO Freezes ASM Cache for a diskgroup
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HC HSM cache NO Add or Remove from HSM cache
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HM Hang Manager Test Resource NO Resource to Generate Hangs for Hang Manager Testing
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
IC IOServer Client NO Gets a unique client ID
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IF IOServer File NO Synchronizes file operations
II IOS Instance fencing lock NO Signals fencing of a client in an instance
IK IOS instance node fencing NO Signals cluster/node fencing status
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IN in-memory segment NO Serialize in-memory segment create/drop
IP PDB Instance State NO Enqueue used to synchronize instance state changes for PDBs
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JG Job Scheduler1 NO Synchronizes accesses to the job cache1
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
JX SQL STATEMENT QUEUE NO synchronize SQL statement queue operations
JZ Join group dictionary NO Synchronizes modifications to im_domain$ and im_joingroup$
KA Kernel Service ACL NO Global ACL State (Disabled=0/Enabled=1
KD Scheduler Master DBRM NO Determine DBRM master
KE ASM Cached Attributes NO Synchronization of ASM cached attributes
KI KJCI Serialization Enqueue NO Enqueue to Serialize KJCI Cross-Instance Calls
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KL LOB KSI LOCK NO KSI lock for buffer cache and wgc concurrency
KM Scheduler NO Synchronizes various Resource Manager operations
KO Multiple Object Checkpoint NO Coordinates checkpointing of multiple objects
KP Kupp Process Startup NO Synchronizes kupp process startup
KQ ASM Attributes Enque NO Single Inst Sync of ASM attributes
KR Enqueue-Delete Rule NO Synchronize delete rule and add rule to ruleset
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
KV KEY VECTOR NO Synchronizes access to a key vector in an IMA query
KZ ASM:Purge Audit NO Coordinate GEN0 on multiple instances
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MC SGA Log Operation NO Lock held during dml/ddl for a securefile log
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MF SGA Log-Bkt Flush NO Lock held during flushing a log bucket
MG MGA service NO synchronize MGA service
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
MK Master Key NO Serializes enc$ access
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MM MMON Messages NO Process MMON cross-instance messages
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MO MMON restricted session NO Serialize MMON operations for restricted sessions
MP SGA Log Partition NO Lock held during partitioning an instance log
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MV Online Datafile Move NO Synchronizes online datafile move operation or cleanup
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
MX ksz synch NO Used to synchronize storage server info across all nodes
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OD Online DDLs NO Lock to prevent concurrent online DDLs
OE DLM Enqueue Owner Serialization NO Enqueue to serialize access to an Omni Enqueue Owner
OL Outline Name NO Synchronizes accesses to a particular outline name
OP Label Security Profile NO Synchronizes access to the ols$profile table
OQ OLAPI Histories NO Synchronizes access to olapi history resources
OT TEXT: Generic Lock NO Generic Lock on CTX index
OW Encryption Wallet NO Serializes wallet initialization and access
PA Privilege Capture API NO Lock held for modifying or reading a privilege capture
PB PDB DDL Operations NO Enqueue used to synchronize PDB DDL operations
PC Enqueue for kzppctxs NO Lock used for accesing kzppctx in SGA
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PJ DV Policy Admin API NO Lock held for Database Vault policy administration API
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PP GES Plug and Play Enqueue NO Coordinates Adding Plug and Play Instances
PQ Queue Ptning global enq NO Synchronizes partitioning operations on queue table accross instances
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
PW Buffer Cache PreWarm NO Coordinates Direct Loads with Prewarmed cache buffers
PX PDB Recovery Operations NO Enqueue used to synchronize recovery-related PDB operations
Q Row Cache NO Coordinates updates and accesses to row cache objects
RA Real-Time ADDM Flood Control NO Coordinate Flood Control in RAC
RB ASM Rollback Recovery NO Serializes ASM rollback recovery operations
RC Result Cache: Enqueue NO Accessing a result in the result-set cache
RD RAC Load NO synchronize update of RAC load info
RE Block Repair/Resilvering NO Synchronizes block repair/mirror resilvering operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RG Replication Global NO Coordinates instance-wide replication / streams operations
RI Reader Farm SQL Isolation NO Reader Farm SQL Isolation
RK wallet_set_mkey NO Serializes wallet master key rekey
RL RAC Encryption Wallet Lock NO RAC encryption wallet lock
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RQ Enqueue-Cross SCN NO Synchronize enqueue-dequeue-cross on SCN generation
RR Workload Capture and Replay NO Prevents concurrent invokers of DBMS_WORKLOAD_*
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
RU Rolling Migration NO Serilized rolling migration operations
RW Materialized View Flags NO Lock used when creating or readingmaterialized view flags in detail tables
RX ASM Extent Relocation Lock NO Synchronizes relocating ASM extents
RZ RFS Logminer FLC NO Synchronizes updates to logminer foreign log cache
SA Purge SRL NO Coordinates access to SRL by RFS and recovery process
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SE Session Migration NO Lock used by transparent session migration
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SG OLS groups NO Synchronizes access to ols$groups table
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SJ KTSJ Slave Task Cancel NO Serializes cancelling task executed by slave process
SK Shrink Segment NO Serialize shrink of a segment
SL Serialize Lock request NO Request serialization to LCK0
SM SMON Serialization NO Lock to check SMON global work in RAC
SN PDB SGA ALLOCATION NO Synchronize PDB SGA Allocation
SO Shared Object NO Synchronizes access to Shared Object(PL/SQL Shared Object Manager)
SP Spare Enqueue 0 NO Spare enqueue 0 for one-off backports
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
SX Spare Enqueue 1 NO Spare enqueue 1 for one-off backports
SY IM chunk populate NO Lock used to serialize in-memory chunk populates
SZ IM segment populate NO Lock used to serialize in-memory segment populates
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TG In Memory Temp Object NO access to imcdt global resource
TH Threshold Chain NO Serializes threshold in-memory chain access
TI In Memory Temp Object HT NO access to an imcdt object HT
TK Auto Task Serialization NO Prevents more than one AutoTask Background Slave from being spawned
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TP Runtime Fixed Table Purge NO Lock used for fixed runtime table purge and definition
TQ Queue table enqueue NO Synchronizes access to queue table
TR Tablespace Rekey NO Coordinates tablespace rekey
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TU TOP UPD NO Enqueue to serialize updates to topology data
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
TZ in-memory NO Serialize in-memory area create/drop
UF AWR undostat stat flush for PDB NO This enqueue is used to serialize undo stat flush per PDB
US Undo Segment NO Lock held to perform DDL on the undo segment
UT Transfer Unified Audit Records NO Lock held for transfer of unified audit records
V Library Cache Lock 3 NO Synchronizes accesses to library cache objects
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WF AWR Flush NO This enqueue is used to serialize the flushing of snapshots
WG Write gather local enqueue NO Long term lock on wgc file state
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WM WLM Plan Operations NO Synchronizes new WLM Plan activation
WP AWR Purge NO This enqueue handles concurrency between purging and baselines
WR LNS archiving log NO Coordinates access to logs by Async LNS and ARCH/FG
WS Logwriter member NO Used by Logwriter to coordinate communication to databases
WT AWR CDB-Wide Table Lock NO This enqueue serializes CDB-Wide Operation on AWR Table
XB ASM Group Block lock NO Prevents client diskgroup use during storage reconfiguration
XC XDB Configuration NO Synchronization access to XDB configuration
XD Auto Online Exadata disks NO Serialize Auto Management of Exadata disks
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XK GES Test-Lock for KSIRESTXDV NO Lock used for internal testing
XL ASM Extent Fault Lock NO Keep multiple processes from faulting in the same extent chunk
XM ASM RM Master Lock NO RMON which process this lock is the Master
XQ ASM Extent Relocation Enqueue NO ASM extent relocation
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing
Y Library Cache Pin 3 NO Synchronizes accesses to the contents of library cache objects
ZA Audit Partition NO Lock held for adding partition to Aud table
ZB in-memory TS NO Serialize in-memory tablespace create/drop
ZC IM FastStart Admin NO Lock used to serialize in-memory FS tasks
ZD IM FastStart CU NO Lock used to serialize in-memory FS CU
ZF FGA Partition NO Lock held for adding partition to Fga table
ZG File Group NO Coordinates file group operations
ZL Foreign Log Maintenance NO Synchronizes updates to foreign log metadata by LogMiner reader and RFS processes
ZP Private Temp Table synchronize NO Synchronizes add/remove/read of PTT-GTT mapping
ZQ quiesce enq NO Serialize SMU create and load quiesce
ZR ZDLRA Server NO Lock held by a recovery server operation to allow other operations to wait for it
ZS Spillover Audit files NO Lock held for exclusive access on a Spillover audit file
ZX repopulation file access NO synchronizes file operations during repopulation
ZZ Global Context Action NO Lock held for updating Global context hash tables

Top

Oracle 12c R2 lock types

Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 – 64bit Production

Total: 280

TYPE NAME IS_USER DESCRIPTION
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
ZH Compression Analyzer YES Synchronizes analysis and insert into compression$, prevents multiple threads analyzing the same table during a load
AB Auto BMR NO A general class of locks used by auto BMR for various purposes
AC Application Continuity NO Synchronizes new service activation
AD ASM Disk AU Lock NO Synchronizes accesses to a specific ASM disk AU
AE Edition Lock NO Prevent Dropping an edition in use
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AH ASM Relocation Lock High NO Protects locked extent pointers during ASM file relocation
AK GES Deadlock Test NO Lock used for internal testing
AM ASM Enqueue NO ASM instance general-purpose enqueue
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AP SPM Autopurge NO This enqueue is used to serialize the purging of SQL plan baselines
AQ Queue Partitioning local enqueue NO Synchronizes partition operations on queue table within instance
AR ASM Relocation Lock NO Protects locked extent pointers during ASM file relocation
AS Service Operations NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AU DBKR NO This enqueue is used to serialize ADR purge operation
AV ASM volume locks NO id1 is for persistent DG number locking. id2 is for other volume serialization
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
AY KSXA Test Affinity Dictionary NO Affinity Dictionary test affinity synchronization
AZ Emon-SRVNTFN_Q Create NO Synchronize creation of AQ_SRVNTFN_Q among emon slaves
BA non durable sub bmap alloc NO Synchronizes access to globl Bitmap Alloc
BB Global Transaction Branch NO 2PC distributed transaction branch across RAC instances
BC BA Container NO Backup Appliance Container
BE Critical Block Allocation NO Lock used to serialize allocation of critical blocks
BF BLOOM FILTER NO Synchronize access to a bloom filter in a parallel statement
BI BA Contained File Identification NO Backup Appliance Contained File Identification
BM clonedb bitmap file access NO synchronizes clonedb bitmap file operations
BO DRM Banned-Object List NO Coordinates dynamic remastering banned-object list
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
BS Backup/Restore spare enq NO KRB space usage
BU Buddy Instance Context NO synchronizes access to Recovery Set constructed by RMS0
BV BA Group Rebuild/Validate NO Backup Appliance Container Rebuild/Validate
BZ BA Contained File Resize NO Backup Appliance Contained File Resize
CA Calibration NO Lock used by IO Calibration
CB CBAC Master Lock NO Synchronizes accesses to the CBAC roles cached in KGL
CC Column Key NO Serializes Column Encryption Key Cache
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM ASM Instance Enqueue NO ASM instance and gate enqueue
CN KTCN REG enq NO Enqueue held for registrations for change notifications
CO KTUCLO Master Slave enq NO Enqueue held for determining Master Slaves
CP Pluggable Database NO Coordinate pluggable database operations
CQ Cleanup querycache registrations NO Serializes access to cleanup client query cache registrations
CR Reuse Block Range NO Coordinates checkpointing of block range reuse
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
CX TEXT: Index Specific Lock NO Index Specific Lock on CTX index
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open or pluggable database open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DO ASM Disk Online Lock NO Synchronizes disk onlines and their recovery
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DW In memory Dispenser NO Serialize in memory dispenser operations
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FE KTFA Recovery NO Flashback archive Enqueue to serialize recovery
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FH Flush Stat NO Serializes flush of ILM stats to disk
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FO Oracle File System Operation NO Synchronize Oracle File System Operations
FP File Object NO Synchronizes various File Object(FOB) operations
FR Disk Group Recovery NO enqueue to control ASM recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
FW Flashback Writer NO Coordinate RVWR on multiple instances
FX ACD Xtnt Info CIC NO serialize ACD relocation CIC
FZ ASM Freezing Cache Lock NO Freezes ASM Cache for a diskgroup
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HC HSM cache NO Add or Remove from HSM cache
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HM Hang Manager Test Resource NO Resource to Generate Hangs for Hang Manager Testing
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
IC IOServer Client NO Gets a unique client ID
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IF IOServer File NO Synchronizes file operations
II IOS Instance fencing lock NO Signals fencing of a client in an instance
IK IOS instance node fencing NO Signals cluster/node fencing status
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IN in-memory segment NO Serialize in-memory segment create/drop
IP PDB Instance State NO Enqueue used to synchronize instance state changes for PDBs
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JG Job Scheduler1 NO Synchronizes accesses to the job cache1
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
JX SQL STATEMENT QUEUE NO synchronize SQL statement queue operations
JZ Join group dictionary NO Synchronizes modifications to im_domain$ and im_joingroup$
KA Kernel Service ACL NO Global ACL State (Disabled=0/Enabled=1
KD Scheduler Master DBRM NO Determine DBRM master
KE ASM Cached Attributes NO Synchronization of ASM cached attributes
KI KJCI Serialization Enqueue NO Enqueue to Serialize KJCI Cross-Instance Calls
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KL LOB KSI LOCK NO KSI lock for buffer cache and wgc concurrency
KM Scheduler NO Synchronizes various Resource Manager operations
KO Multiple Object Checkpoint NO Coordinates checkpointing of multiple objects
KP Kupp Process Startup NO Synchronizes kupp process startup
KQ ASM Attributes Enque NO Single Inst Sync of ASM attributes
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
KV KEY VECTOR NO Synchronizes access to a key vector in an IMA query
KZ ASM:Purge Audit NO Coordinate GEN0 on multiple instances
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MC SGA Log Operation NO Lock held during dml/ddl for a securefile log
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MF SGA Log-Bkt Flush NO Lock held during flushing a log bucket
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
MK Master Key NO Serializes enc$ access
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MM MMON Messages NO Process MMON cross-instance messages
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MO MMON restricted session NO Serialize MMON operations for restricted sessions
MP SGA Log Partition NO Lock held during partitioning an instance log
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MV Online Datafile Move NO Synchronizes online datafile move operation or cleanup
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
MX ksz synch NO Used to synchronize storage server info across all nodes
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OD Online DDLs NO Lock to prevent concurrent online DDLs
OE DLM Enqueue Owner Serialization NO Enqueue to serialize access to an Omni Enqueue Owner
OL Outline Name NO Synchronizes accesses to a particular outline name
OP Label Security Profile NO Synchronizes access to the ols$profile table
OQ OLAPI Histories NO Synchronizes access to olapi history resources
OT TEXT: Generic Lock NO Generic Lock on CTX index
OW Encryption Wallet NO Serializes wallet initialization and access
PA Privilege Capture API NO Lock held for modifying or reading a privilege capture
PB PDB DDL Operations NO Enqueue used to synchronize PDB DDL operations
PC Enqueue for kzppctxs NO Lock used for accesing kzppctx in SGA
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PJ DV Policy Admin API NO Lock held for Database Vault policy administration API
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PP GES Plug and Play Enqueue NO Coordinates Adding Plug and Play Instances
PQ Queue Ptning global enq NO Synchronizes partitioning operations on queue table accross instances
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
PW Buffer Cache PreWarm NO Coordinates Direct Loads with Prewarmed cache buffers
PX PDB Recovery Operations NO Enqueue used to synchronize recovery-related PDB operations
Q Row Cache NO Coordinates updates and accesses to row cache objects
RA Real-Time ADDM Flood Control NO Coordinate Flood Control in RAC
RB ASM Rollback Recovery NO Serializes ASM rollback recovery operations
RC Result Cache: Enqueue NO Accessing a result in the result-set cache
RD RAC Load NO synchronize update of RAC load info
RE Block Repair/Resilvering NO Synchronizes block repair/mirror resilvering operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RG Replication Global NO Coordinates instance-wide replication / streams operations
RK wallet_set_mkey NO Serializes wallet master key rekey
RL RAC Encryption Wallet Lock NO RAC encryption wallet lock
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RQ Enqueue-Cross SCN NO Synchronize enqueue-dequeue-cross on SCN generation
RR Workload Capture and Replay NO Prevents concurrent invokers of DBMS_WORKLOAD_*
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
RU Rolling Migration NO Serilized rolling migration operations
RW Materialized View Flags NO Lock used when creating or readingmaterialized view flags in detail tables
RX ASM Extent Relocation Lock NO Synchronizes relocating ASM extents
RZ RFS Logminer FLC NO Synchronizes updates to logminer foreign log cache
SA Purge SRL NO Coordinates access to SRL by RFS and recovery process
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SE Session Migration NO Lock used by transparent session migration
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SG OLS groups NO Synchronizes access to ols$groups table
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SJ KTSJ Slave Task Cancel NO Serializes cancelling task executed by slave process
SK Shrink Segment NO Serialize shrink of a segment
SL Serialize Lock request NO Request serialization to LCK0
SM SMON Serialization NO Lock to check SMON global work in RAC
SN PDB SGA ALLOCATION NO Synchronize PDB SGA Allocation
SO Shared Object NO Synchronizes access to Shared Object(PL/SQL Shared Object Manager)
SP Spare Enqueue 0 NO Spare enqueue 0 for one-off backports
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
SX Spare Enqueue 1 NO Spare enqueue 1 for one-off backports
SY IM chunk populate NO Lock used to serialize in-memory chunk populates
SZ IM segment populate NO Lock used to serialize in-memory segment populates
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TG In Memory Temp Object NO access to imcdt global resource
TH Threshold Chain NO Serializes threshold in-memory chain access
TI In Memory Temp Object HT NO access to an imcdt object HT
TK Auto Task Serialization NO Prevents more than one AutoTask Background Slave from being spawned
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TP Runtime Fixed Table Purge NO Lock used for fixed runtime table purge and definition
TQ Queue table enqueue NO Synchronizes access to queue table
TR Tablespace Rekey NO Coordinates tablespace rekey
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TU TOP UPD NO Enqueue to serialize updates to topology data
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
TZ in-memory NO Serialize in-memory area create/drop
UF AWR undostat stat flush for PDB NO This enqueue is used to serialize undo stat flush per PDB
UM UMF Auto Task Pool Queue NO Enqueue to serialize queue scheduler and queue servers
US Undo Segment NO Lock held to perform DDL on the undo segment
UT Transfer Unified Audit Records NO Lock held for transfer of unified audit records
V Library Cache Lock 3 NO Synchronizes accesses to library cache objects
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WF AWR Flush NO This enqueue is used to serialize the flushing of snapshots
WG Write gather local enqueue NO Long term lock on wgc file state
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WM WLM Plan Operations NO Synchronizes new WLM Plan activation
WP AWR Purge NO This enqueue handles concurrency between purging and baselines
WR LNS archiving log NO Coordinates access to logs by Async LNS and ARCH/FG
WS LogWriter Standby NO Used by LogWriter to coordinate communication to standby databases
WT AWR CDB-Wide Table Lock NO This enqueue serializes CDB-Wide Operation on AWR Table
XB ASM Group Block lock NO Prevents client diskgroup use during storage reconfiguration
XC XDB Configuration NO Synchronization access to XDB configuration
XD Auto Online Exadata disks NO Serialize Auto Management of Exadata disks
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XK GES Test-Lock for KSIRESTXDV NO Lock used for internal testing
XL ASM Extent Fault Lock NO Keep multiple processes from faulting in the same extent chunk
XM ASM RM Master Lock NO RMON which process this lock is the Master
XQ ASM Extent Relocation Enqueue NO ASM extent relocation
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing
Y Library Cache Pin 3 NO Synchronizes accesses to the contents of library cache objects
ZA Audit Partition NO Lock held for adding partition to Aud table
ZB in-memory TS NO Serialize in-memory tablespace create/drop
ZC IM FastStart Admin NO Lock used to serialize in-memory FS tasks
ZD IM FastStart CU NO Lock used to serialize in-memory FS CU
ZF FGA Partition NO Lock held for adding partition to Fga table
ZG File Group NO Coordinates file group operations
ZL Foreign Log Maintenance NO Synchronizes updates to foreign log metadata by LogMiner reader and RFS processes
ZQ quiesce enq NO Serialize SMU create and load quiesce
ZR ZDLRA Server NO Lock held by a recovery server operation to allow other operations to wait for it
ZS Spillover Audit files NO Lock held for exclusive access on a Spillover audit file
ZX repopulation file access NO synchronizes file operations during repopulation
ZZ Global Context Action NO Lock held for updating Global context hash tables

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Oracle 12c R1 lock types

Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 – 64bit Production

Total: 256 (it really is 🙂 )

TYPE NAME IS_USER DESCRIPTION
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
ZH Compression Analyzer YES Synchronizes analysis and insert into compression$, prevents multiple threads analyzing the same table during a load
AB Auto BMR NO A general class of locks used by auto BMR for various purposes
AC Application Continuity NO Synchronizes new service activation
AD ASM Disk AU Lock NO Synchronizes accesses to a specific ASM disk AU
AE Edition Lock NO Prevent Dropping an edition in use
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AH ASM Relocation Lock High NO Protects locked extent pointers during ASM file relocation
AK GES Deadlock Test NO Lock used for internal testing
AM ASM Enqueue NO ASM instance general-purpose enqueue
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AP SPM Autopurge NO This enqueue is used to serialize the purging of SQL plan baselines
AQ Queue Partitioning local enqueue NO Synchronizes partition operations on queue table within instance
AR ASM Relocation Lock NO Protects locked extent pointers during ASM file relocation
AS Service Operations NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AV ASM volume locks NO id1 is for persistent DG number locking. id2 is for other volume serialization
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
AY KSXA Test Affinity Dictionary NO Affinity Dictionary test affinity synchronization
BA non durable sub bmap alloc NO Synchronizes access to globl Bitmap Alloc
BB Global Transaction Branch NO 2PC distributed transaction branch across RAC instances
BC BA Container NO Backup Appliance Container
BF BLOOM FILTER NO Synchronize access to a bloom filter in a parallel statement
BI BA Contained File Identification NO Backup Appliance Contained File Identification
BM clonedb bitmap file access NO synchronizes clonedb bitmap file operations
BO DRM Banned-Object List NO Coordinates dynamic remastering banned-object list
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
BS Backup/Restore spare enq NO KRB space usage
BV BA Group Rebuild/Validate NO Backup Appliance Container Rebuild/Validate
BZ BA Contained File Resize NO Backup Appliance Contained File Resize
CA Calibration NO Lock used by IO Calibration
CB CBAC Master Lock NO Synchronizes accesses to the CBAC roles cached in KGL
CC Column Key NO Serializes Column Encryption Key Cache
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM ASM Instance Enqueue NO ASM instance and gate enqueue
CN KTCN REG enq NO Enqueue held for registrations for change notifications
CO KTUCLO Master Slave enq NO Enqueue held for determining Master Slaves
CP Pluggable Database NO Coordinate pluggable database operations
CQ Cleanup querycache registrations NO Serializes access to cleanup client query cache registrations
CR Reuse Block Range NO Coordinates checkpointing of block range reuse
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
CX TEXT: Index Specific Lock NO Index Specific Lock on CTX index
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open or pluggable database open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DO ASM Disk Online Lock NO Synchronizes disk onlines and their recovery
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DW In memory Dispenser NO Serialize in memory dispenser operations
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FE KTFA Recovery NO Flashback archive Enqueue to serialize recovery
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FH Flush Stat NO Serializes flush of ILM stats to disk
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FO Oracle File System Operation NO Synchronize Oracle File System Operations
FP File Object NO Synchronizes various File Object(FOB) operations
FR Disk Group Recovery NO enqueue to control ASM recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
FW Flashback Writer NO Coordinate RVWR on multiple instances
FX ACD Xtnt Info CIC NO serialize ACD relocation CIC
FZ ASM Freezing Cache Lock NO Freezes ASM Cache for a diskgroup
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HC HSM cache NO Add or Remove from HSM cache
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HM Hang Manager Test Resource NO Resource to Generate Hangs for Hang Manager Testing
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
IC IOServer Client NO Gets a unique client ID
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IF IOServer File NO Synchronizes file operations
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IN in-memory segment NO Serialize in-memory segment create/drop
IP PDB Instance State NO Enqueue used to synchronize instance state changes for PDBs
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
JX SQL STATEMENT QUEUE NO synchronize SQL statement queue operations
KD Scheduler Master DBRM NO Determine DBRM master
KE ASM Cached Attributes NO Synchronization of ASM cached attributes
KI KJCI Serialization Enqueue NO Enqueue to Serialize KJCI Cross-Instance Calls
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KL LOB KSI LOCK NO KSI lock for buffer cache and wgc concurrency
KM Scheduler NO Synchronizes various Resource Manager operations
KO Multiple Object Checkpoint NO Coordinates checkpointing of multiple objects
KP Kupp Process Startup NO Synchronizes kupp process startup
KQ ASM Attributes Enque NO Single Inst Sync of ASM attributes
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
KV KEY VECTOR NO Synchronizes access to a key vector in a parallel statement
KZ ASM:Purge Audit NO Coordinate GEN0 on multiple instances
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MC SGA Log Operation NO Lock held during dml/ddl for a securefile log
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MF SGA Log-Bkt Flush NO Lock held during flushing a log bucket
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
MK Master Key NO Serializes enc$ access
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MO MMON restricted session NO Serialize MMON operations for restricted sessions
MP SGA Log Partition NO Lock held during partitioning an instance log
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MV Online Datafile Move NO Synchronizes online datafile move operation or cleanup
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
MX ksz synch NO Used to synchronize storage server info across all nodes
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OD Online DDLs NO Lock to prevent concurrent online DDLs
OE DLM Enqueue Owner Serialization NO Enqueue to serialize access to an Omni Enqueue Owner
OL Outline Name NO Synchronizes accesses to a particular outline name
OP Label Security Profile NO Synchronizes access to the ols$profile table
OQ OLAPI Histories NO Synchronizes access to olapi history resources
OT TEXT: Generic Lock NO Generic Lock on CTX index
OW Encryption Wallet NO Serializes wallet initialization and access
PA Privilege Capture API NO Lock held for modifying or reading a privilege capture
PB PDB DDL Operations NO Enqueue used to synchronize PDB DDL operations
PC Enqueue for kzppctxs NO Lock used for accesing kzppctx in SGA
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PP GES Plug and Play Enqueue NO Coordinates Adding Plug and Play Instances
PQ Queue Ptning global enq NO Synchronizes partitioning operations on queue table accross instances
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
PW Buffer Cache PreWarm NO Coordinates Direct Loads with Prewarmed cache buffers
PY AVM RTA Access NO Coordinate RTA info access on AVM
Q Row Cache NO Coordinates updates and accesses to row cache objects
RA Real-Time ADDM Flood Control NO Coordinate Flood Control in RAC
RB ASM Rollback Recovery NO Serializes ASM rollback recovery operations
RC Result Cache: Enqueue NO Accessing a result in the result-set cache
RD RAC Load NO synchronize update of RAC load info
RE Block Repair/Resilvering NO Synchronizes block repair/mirror resilvering operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RK wallet_set_mkey NO Serializes wallet master key rekey
RL RAC Encryption Wallet Lock NO RAC encryption wallet lock
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RQ Enqueue-Cross SCN NO Synchronize enqueue-dequeue-cross on SCN generation
RR Workload Capture and Replay NO Prevents concurrent invokers of DBMS_WORKLOAD_*
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
RU Rolling Migration NO Serilized rolling migration operations
RW Materialized View Flags NO Lock used when creating or readingmaterialized view flags in detail tables
RX ASM Extent Relocation Lock NO Synchronizes relocating ASM extents
RZ RFS Logminer FLC NO Synchronizes updates to logminer foreign log cache
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SE Session Migration NO Lock used by transparent session migration
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SG OLS groups NO Synchronizes access to ols$groups table
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SJ KTSJ Slave Task Cancel NO Serializes cancelling task executed by slave process
SK Shrink Segment NO Serialize shrink of a segment
SL Serialize Lock request NO Request serialization to LCK0
SM SMON Serialization NO Lock to check SMON global work in RAC
SO Shared Object NO Synchronizes access to Shared Object(PL/SQL Shared Object Manager)
SP Spare Enqueue 0 NO Spare enqueue 0 for one-off backports
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
SX Spare Enqueue 1 NO Spare enqueue 1 for one-off backports
SY IM chunk populate NO Lock used to serialize in-memory chunk populates
SZ IM segment populate NO Lock used to serialize in-memory segment populates
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TH Threshold Chain NO Serializes threshold in-memory chain access
TK Auto Task Serialization NO Prevents more than one AutoTask Background Slave from being spawned
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TP Runtime Fixed Table Purge NO Lock used for fixed runtime table purge and definition
TQ Queue table enqueue NO Synchronizes access to queue table
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
TZ in-memory NO Serialize in-memory area create/drop
US Undo Segment NO Lock held to perform DDL on the undo segment
V Library Cache Lock 3 NO Synchronizes accesses to library cache objects
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WF AWR Flush NO This enqueue is used to serialize the flushing of snapshots
WG Write gather local enqueue NO Long term lock on wgc file state
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WM WLM Plan Operations NO Synchronizes new WLM Plan activation
WP AWR Purge NO This enqueue handles concurrency between purging and baselines
WR LNS archiving log NO Coordinates access to logs by Async LNS and ARCH/FG
WS LogWriter Standby NO Used by LogWriter to coordinate communication to standby databases
WT AWR CDB-Wide Table Lock NO This enqueue serializes CDB-Wide Operation on AWR Table
XB ASM Group Block lock NO Prevents client diskgroup use during storage reconfiguration
XC XDB Configuration NO Synchronization access to XDB configuration
XD Auto Online Exadata disks NO Serialize Auto Management of Exadata disks
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XK GES Test-Lock for KSIRESTXDV NO Lock used for internal testing
XL ASM Extent Fault Lock NO Keep multiple processes from faulting in the same extent chunk
XM ASM RM Master Lock NO RMON which process this lock is the Master
XQ ASM Extent Relocation Enqueue NO ASM extent relocation
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing
Y Library Cache Pin 3 NO Synchronizes accesses to the contents of library cache objects
ZA Audit Partition NO Lock held for adding partition to Aud table
ZB in-memory TS NO Serialize in-memory tablespace create/drop
ZC IM FastStart Seg NO Lock used to serialize in-memory FS seg
ZD IM FastStart CU NO Lock used to serialize in-memory FS CU
ZF FGA Partition NO Lock held for adding partition to Fga table
ZG File Group NO Coordinates file group operations
ZS Spillover Audit files NO Lock held for exclusive access on a Spillover audit file
ZX repopulation file access NO synchronizes file operations during repopulation
ZZ Global Context Action NO Lock held for updating Global context hash tables

Top

Oracle 11g R2 lock types

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 – 64bit Production

Total: 209

TYPE NAME IS_USER DESCRIPTION
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
ZH Compression Analyzer YES Synchronizes analysis and insert into compression$, prevents multiple threads analyzing the same table during a load
AB Auto BMR NO A general class of locks used by auto BMR for various purposes
AD ASM Disk AU Lock NO Synchronizes accesses to a specific ASM disk AU
AE Edition Lock NO Prevent Dropping an edition in use
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AK GES Deadlock Test NO Lock used for internal testing
AM ASM Enqueue NO ASM instance general-purpose enqueue
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AP SPM Autopurge NO This enqueue is used to serialize the purging of SQL plan baselines
AR ASM Relocation Lock NO Protects locked extent pointers during ASM file relocation
AS Service Operations NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AV ASM volume locks NO id1 is for persistent DG number locking. id2 is for other volume serialization
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
AY KSXA Test Affinity Dictionary NO Affinity Dictionary test affinity synchronization
BB Global Transaction Branch NO 2PC distributed transaction branch across RAC instances
BF BLOOM FILTER NO Synchronize access to a bloom filter in a parallel statement
BM clonedb bitmap file access NO synchronizes clonedb bitmap file operations
BO DRM Banned-Object List NO Coordinates dynamic remastering banned-object list
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
BS Backup/Restore spare enq NO KRB space usage
CA Calibration NO Lock used by IO Calibration
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM ASM Instance Enqueue NO ASM instance and gate enqueue
CN KTCN REG enq NO Enqueue held for registrations for change notifications
CO KTUCLO Master Slave enq NO Enqueue held for determining Master Slaves
CQ Cleanup querycache registrations NO Serializes access to cleanup client query cache registrations
CR Reuse Block Range NO Coordinates checkpointing of block range reuse
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
CX TEXT: Index Specific Lock NO Index Specific Lock on CTX index
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DO ASM Disk Online Lock NO Synchronizes disk onlines and their recovery
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DW In memory Dispenser NO Serialize in memory dispenser operations
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FE KTFA Recovery NO Flashback archive Enqueue to serialize recovery
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FP File Object NO Synchronizes various File Object(FOB) operations
FR Disk Group Recovery NO enqueue to control ASM recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
FW Flashback Writer NO Coordinate RVWR on multiple instances
FX ACD Xtnt Info CIC NO serialize ACD relocation CIC
FZ ASM Freezing Cache Lock NO Freezes ASM Cache for a diskgroup
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
JX SQL STATEMENT QUEUE NO synchronize SQL statement queue operations
KD Scheduler Master DBRM NO Determine DBRM master
KE ASM Cached Attributes NO Synchronization of ASM cached attributes
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KL LOB KSI LOCK NO KSI lock for buffer cache and wgc concurrency
KM Scheduler NO Synchronizes various Resource Manager operations
KO Multiple Object Checkpoint NO Coordinates checkpointing of multiple objects
KP Kupp Process Startup NO Synchronizes kupp process startup
KQ ASM Attributes Enque NO Single Inst Sync of ASM attributes
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
MK Master Key NO Serializes enc$ access
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MO MMON restricted session NO Serialize MMON operations for restricted sessions
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MV Online Datafile Move NO Synchronizes online datafile move operation or cleanup
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
MX ksz synch NO Used to synchronize storage server info across all nodes
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OD Online DDLs NO Lock to prevent concurrent online DDLs
OL Outline Name NO Synchronizes accesses to a particular outline name
OQ OLAPI Histories NO Synchronizes access to olapi history resources
OT TEXT: Generic Lock NO Generic Lock on CTX index
OW Encryption Wallet NO Serializes wallet initialization and access
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
PW Buffer Cache PreWarm NO Coordinates Direct Loads with Prewarmed cache buffers
Q Row Cache NO Coordinates updates and accesses to row cache objects
RB ASM Rollback Recovery NO Serializes ASM rollback recovery operations
RC Result Cache: Enqueue NO Accessing a result in the result-set cache
RD RAC Load NO synchronize update of RAC load info
RE Block Repair/Resilvering NO Synchronizes block repair/mirror resilvering operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RK wallet_set_mkey NO Serializes wallet master key rekey
RL RAC Encryption Wallet Lock NO RAC encryption wallet lock
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RR Workload Capture and Replay NO Prevents concurrent invokers of DBMS_WORKLOAD_*
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
RU Rolling Migration NO Serilized rolling migration operations
RW Materialized View Flags NO Lock used when creating or readingmaterialized view flags in detail tables
RX ASM Extent Relocation Lock NO Synchronizes relocating ASM extents
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SE Session Migration NO Lock used by transparent session migration
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SJ KTSJ Slave Task Cancel NO Serializes cancelling task executed by slave process
SK Shrink Segment NO Serialize shrink of a segment
SL Serialize Lock request NO Request serialization to LCK0
SM SMON Serialization NO Lock to check SMON global work in RAC
SO Shared Object NO Synchronizes access to Shared Object(PL/SQL Shared Object Manager)
SP Spare Enqueue 0 NO Spare enqueue 0 for one-off backports
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
SX Spare Enqueue 1 NO Spare enqueue 1 for one-off backports
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TH Threshold Chain NO Serializes threshold in-memory chain access
TK Auto Task Serialization NO Prevents more than one AutoTask Background Slave from being spawned
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TP Runtime Fixed Table Purge NO Lock used for fixed runtime table purge and definition
TQ Queue table enqueue NO Synchronizes access to queue table
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
US Undo Segment NO Lock held to perform DDL on the undo segment
V Library Cache Lock 3 NO Synchronizes accesses to library cache objects
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WF AWR Flush NO This enqueue is used to serialize the flushing of snapshots
WG Write gather local enqueue NO Long term lock on wgc file state
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WM WLM Plan Operations NO Synchronizes new WLM Plan activation
WP AWR Purge NO This enqueue handles concurrency between purging and baselines
WR LNS archiving log NO Coordinates access to logs by Async LNS and ARCH/FG
WS LogWriter Standby NO Used by LogWriter to coordinate communication to standby databases
XB ASM Group Block lock NO Prevents client diskgroup use during storage reconfiguration
XC XDB Configuration NO Synchronization access to XDB configuration
XD Auto Online Exadata disks NO Serialize Auto Management of Exadata disks
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XL ASM Extent Fault Lock NO Keep multiple processes from faulting in the same extent chunk
XQ ASM Extent Relocation Enqueue NO ASM extent relocation
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing
Y Library Cache Pin 3 NO Synchronizes accesses to the contents of library cache objects
ZA Audit Partition NO Lock held for adding partition to Aud table
ZF FGA Partition NO Lock held for adding partition to Fga table
ZG File Group NO Coordinates file group operations
ZX repopulation file access NO synchronizes file operations during repopulation
ZZ Global Context Action NO Lock held for updating Global context hash tables

Top

Oracle 11g R1 lock types

Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 – Production

Total: 190

TYPE NAME IS_USER DESCRIPTION
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
AD ASM Disk AU Lock NO Synchronizes accesses to a specific ASM disk AU
AE Edition Lock NO Prevent Dropping an edition in use
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AK GES Deadlock Test NO Lock used for internal testing
AM ASM Enqueue NO ASM instance general-purpose enqueue
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AR ASM Relocation Lock NO Protects locked extent pointers during ASM file relocation
AS Service Operations NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AU Audit index file NO Lock held to synchronize access XML to audit index file
AV AVD DG Number Lock NO AVD DG unique enqueue
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
AY KSXA Test Affinity Dictionary NO Affinity Dictionary test affinity synchronization
BB Global Transaction Branch NO 2PC distributed transaction branch across RAC instances
BF BLOOM FILTER NO Synchronize access to a bloom filter in a parallel statement
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
CA Calibration NO Lock used by IO Calibration
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM ASM Instance Enqueue NO ASM instance and gate enqueue
CN KTCN REG enq NO Enqueue held for registrations for change notifications
CO KTUCLO Master Slave enq NO Enqueue held for determining Master Slaves
CQ Cleanup querycache registrations NO Serializes access to cleanup client query cache registrations
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DO ASM Disk Online Lock NO Synchronizes disk onlines and their recovery
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DW In memory Dispenser NO Serialize in memory dispenser operations
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FE KTFA Recovery NO Flashback archive Enqueue to serialize recovery
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FP File Object NO Synchronizes various File Object(FOB) operations
FR Disk Group Recovery NO local enqueue to serialize with PMON cleanup of a previous recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
FW Flashback Writer NO Coordinate RVWR on multiple instances
FX ACD Xtnt Info CIC NO serialize ACD relocation CIC
FZ ASM Freezing Cache Lock NO Freezes ASM Cache for a diskgroup
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
KE ASM Cached Attributes NO Synchronization of ASM cached attributes
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KL LOB KSI LOCK NO KSI lock for buffer cache and wgc concurrency
KM Scheduler NO Synchronizes various Resource Manager operations
KO Multiple Object Checkpoint NO Coordinates checkpointing of multiple objects
KP Kupp Process Startup NO Synchronizes kupp process startup
KQ ASM Attributes Enque NO Single Inst Sync of ASM attributes
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
MK Master Key NO Serializes enc$ access
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MO MMON restricted session NO Serialize MMON operations for restricted sessions
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
MX ksz synch NO Used to synchronize storage server info across all nodes
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OD Online DDLs NO Lock to prevent concurrent online DDLs
OL Outline Name NO Synchronizes accesses to a particular outline name
OQ OLAPI Histories NO Synchronizes access to olapi history resources
OW Encryption Wallet NO Serializes wallet initialization and access
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
PW Buffer Cache PreWarm NO Coordinates Direct Loads with Prewarmed cache buffers
Q Row Cache NO Coordinates updates and accesses to row cache objects
RB ASM Rollback Recovery NO Serializes ASM rollback recovery operations
RC Result Cache: Enqueue NO Accessing a result in the result-set cache
RE Block Repair/Resilvering NO Synchronizes block repair/mirror resilvering operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RR Workload Capture and Replay NO Prevents concurrent invokers of DBMS_WORKLOAD_*
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
RU Rolling Migration NO Serilized rolling migration operations
RW Materialized View Flags NO Lock used when creating or readingmaterialized view flags in detail tables
RX ASM Extent Relocation Lock NO Synchronizes relocating ASM extents
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SE Session Migration NO Lock used by transparent session migration
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SJ KTSJ Slave Task Cancel NO Serializes cancelling task executed by slave process
SK Shrink Segment NO Serialize shrink of a segment
SL Serialize Lock request NO Request serialization to LCK0
SM SMON Serialization NO Lock to check SMON global work in RAC
SO Shared Object NO Synchronizes access to Shared Object(PL/SQL Shared Object Manager)
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TH Threshold Chain NO Serializes threshold in-memory chain access
TK Auto Task Serialization NO Prevents more than one AutoTask Background Slave from being spawned
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TQ Queue table enqueue NO Synchronizes access to queue table
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
UN User Name NO Protects a user name from being dropped during use
US Undo Segment NO Lock held to perform DDL on the undo segment
V Library Cache Lock 3 NO Synchronizes accesses to library cache objects
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WF AWR Flush NO This enqueue is used to serialize the flushing of snapshots
WG Write gather local enqueue NO Long term lock on wgc file state
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WM WLM Plan Operations NO Synchronizes new WLM Plan activation
WP AWR Purge NO This enqueue handles concurrency between purging and baselines
WR LNS archiving log NO Coordinates access to logs by Async LNS and ARCH/FG
WS LogWriter Standby NO Used by LogWriter to coordinate communication to standby databases
XB ASM Group Block lock NO Prevents client diskgroup use during storage reconfiguration
XC XDB Configuration NO Synchronization access to XDB configuration
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XL ASM Extent Fault Lock NO Keep multiple processes from faulting in the same extent chunk
XQ ASM Extent Relocation Enqueue NO ASM extent relocation
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing
Y Library Cache Pin 3 NO Synchronizes accesses to the contents of library cache objects
ZA Audit Partition NO Lock held for adding partition to Aud table
ZF FGA Partition NO Lock held for adding partition to Fga table
ZG File Group NO Coordinates file group operations

Top

Oracle 10g R2 lock types

Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 – Prod

Total: 162

TYPE NAME IS_USER DESCRIPTION
PW Buffer Cache PreWarm YES Coordinates Direct Loads with Prewarmed cache buffers
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
AD ASM Disk AU Lock NO Synchronizes accesses to a specific ASM disk AU
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AK GES Deadlock Test NO Lock used for internal testing
AM ASM Enqueue NO ASM instance general-purpose enqueue
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AS Service Operations NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AU Audit index file NO Lock held to synchronize access XML to audit index file
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
BF BLOOM FILTER NO Synchronize access to a bloom filter in a parallel statement
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM ASM Instance Enqueue NO ASM instance and gate enqueue
CN KTCN REG enq NO Enqueue held for registrations for change notifications
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FP File Object NO Synchronizes various File Object(FOB) operations
FR Disk Group Recovery NO local enqueue to serialize with PMON cleanup of a previous recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
FW Flashback Writer NO Coordinate RVWR on multiple instances
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KM Scheduler NO Synchronizes various Resource Manager operations
KO Multiple Object Checkpoint NO Coordinates checkpointing of multiple objects
KP Kupp Process Startup NO Synchronizes kupp process startup
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
MK Master Key NO Serializes enc$ access
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MO MMON restricted session NO Serialize MMON operations for restricted sessions
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OL Outline Name NO Synchronizes accesses to a particular outline name
OQ OLAPI Histories NO Synchronizes access to olapi history resources
OW Encryption Wallet NO Serializes wallet initialization and access
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
Q Row Cache NO Coordinates updates and accesses to row cache objects
RB ASM Rollback Recovery NO Serializes ASM rollback recovery operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RR Workload Capture and Replay NO Prevents concurrent invokers of DBMS_WORKLOAD_*
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
RU Rolling Upgrade NO Serilized rolling upgrade operations
RW Materialized View Flags NO Lock used when creating or readingmaterialized view flags in detail tables
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SE Session Migration NO Lock used by transparent session migration
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SK Shrink Segment NO Serialize shrink of a segment
SM SMON Serialization NO Lock to check SMON global work in RAC
SP Spare Enqueue NO Spare enqueue for one-off backports
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TH Threshold Chain NO Serializes threshold in-memory chain access
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TQ Queue table enqueue NO Synchronizes access to queue table
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
UN User Name NO Protects a user name from being dropped during use
US Undo Segment NO Lock held to perform DDL on the undo segment
V Library Cache Lock 3 NO Synchronizes accesses to library cache objects
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WF AWR Flush NO This enqueue is used to serialize the flushing of snapshots
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WP AWR Purge NO This enqueue handles concurrency between purging and baselines
WR LNS archiving log NO Coordinates access to logs by Async LNS and ARCH/FG
WS LogWriter Standby NO Used by LogWriter to coordinate communication to standby databases
XB ASM Group Block lock NO Prevents client diskgroup use during storage reconfiguration
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XQ ASM Extent Relocation Enqueue NO ASM extent relocation
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing
Y Library Cache Pin 3 NO Synchronizes accesses to the contents of library cache objects
ZA Audit Partition NO Lock held for adding partition to Aud table
ZF FGA Partition NO Lock held for adding partition to Fga table
ZG File Group NO Coordinates file group operations

Top

Oracle 10g R1 lock types

Oracle Database 10g Enterprise Edition Release 10.1.0.5.0 – Prod

Total: 138

TYPE NAME IS_USER DESCRIPTION
PW Buffer Cache PreWarm YES Coordinates Direct Loads with Prewarmed cache buffers
TM DML YES Synchronizes accesses to an object
TX Transaction YES Lock held by a transaction to allow other transactions to wait for it
UL User-defined YES Lock used by user applications
AD OSM Disk AU Lock NO Synchronizes accesses to a specific OSM disk AU
AF Advisor Framework NO This enqueue is used to serialize access to an advisor task
AG Analytic Workspace Generation NO Synchronizes generation use of a particular workspace
AK GES Deadlock Test NO Lock used for internal testing
AO MultiWriter Object Access NO Synchronizes access to objects and scalar variables
AS Activate Service NO Synchronizes new service activation
AT Alter Tablespace NO Serializes ‘alter tablespace’ operations
AW Analytic Workspace NO Synchronizes access to Analytic Workspace resources
BR Backup/Restore NO Lock held by a backup/restore operation to allow other operations to wait for it
CF Controlfile Transaction NO Synchronizes accesses to the controlfile
CI Cross-Instance Call Invocation NO Coordinates cross-instance function invocations
CL Label Security cache NO Synchronizes accesses to label cache and label tables
CM OSM Instance Enqueue NO OSM instance and gate enqueue
CT Block Change Tracking NO A general class of locks used by change tracking for various purposes
CU Cursor NO Recovers cursors in case of death while compiling
DB DbsDriver NO Synchronizes modification of database wide supplementallogging attributes
DD ASM Local Disk Group NO Synchronizes local accesses to ASM disk groups
DF Datafile Online in RAC NO Enqueue held by foreground or DBWR when a datafile is brought online in RAC
DG ASM Disk Group Modification NO Synchronizes accesses to ASM disk groups
DI GES Internal NO Coordinates Global Enqueue Service deadlock detection
DL Direct Loader Index Creation NO Lock to prevent index DDL during direct load
DM Database Mount/Open NO Enqueue held by foreground or DBWR to synchronize database mount/open with other operations
DN Diskgroup number generator NO Serializes Group number generations
DP LDAP Parameter NO Synchronizes access to LDAP parameters
DQ ASM RBAL doorbell NO Inter-RBAL process metadata invalidation notification
DR Distributed Recovery NO Serializes the active distributed recovery operation
DS Database Suspend NO Prevents a database suspend during LMON reconfiguration
DT Default Temporary Tablespace NO Serializes changing the default temporary table space and user creation
DV Diana Versioning NO Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
DX Distributed Transaction NO Serializes tightly coupled distributed transaction branches
E Library Cache Lock 2 NO Synchronizes accesses to library cache objects
FA ASM File Access Lock NO Synchronizes accesses to open ASM files
FB Format Block NO Ensures that only one process can format data blocks in auto segment space managed tablespaces
FC Disk Group Chunk Mount NO controls access to an ACD chunk
FD Flashback Database NO Coordinate flashback database
FG ACD Relocation Gate Enqueue NO ACD relocation serialization
FL Flashback database log NO Synchronize access to flashback database log
FM File Mapping NO Synchronizes access to global file mapping state
FR Disk Group Recovery NO local enqueue to serialize with PMON cleanup of a previous recovery
FS File Set / Dictionary Check NO Enqueue used to synchronize recovery and file operations or synchronize dictionary check
FT Disk Group Redo Generation NO controls the privilege to generate redo in a thread
FU DBFUS NO This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
G Library Cache Pin 2 NO Synchronizes accesses to the contents of library cache objects
HD ASM Disk Header NO Serializes accesses to ASM SGA data structures
HP Queue Page NO Synchronizes accesses to queue pages
HQ Hash Queue NO Synchronizes the creation of new queue IDs
HV Direct Loader High Water Mark NO Lock used to broker the high water mark during parallel inserts
HW Segment High Water Mark NO Lock used to broker the high water mark during parallel inserts
IA Internal NO
ID NID NO Lock held by a NID operation to allow other operations to wait for it
IL Label Security NO Synchronizes accesses to internal label data structures
IM Kti blr lock NO Serializes block recovery for an IMU txn
IR Instance Recovery NO Synchronizes instance recovery
IS Instance State NO Enqueue used to synchronize instance state changes
IT In-Mem Temp Table Meta Creation NO Synchronizes accesses to a temp object’s metadata
IV Library Cache Invalidation NO Synchronizes library cache object invalidations across instances
IZ INSTANCE LOCK NO Proctects the lock name space used by the instance
JD Job Queue Date NO Synchronizes dates between job queue coordinator and slave processes
JI Materialized View NO Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
JQ Job Queue NO Lock to prevent multiple instances from running a single job
JS Job Scheduler NO Synchronizes accesses to the job cache
KK Kick Instance to Switch Logs NO Lock held by open redo thread, used by other instances to force a log switch
KM Scheduler NO Synchronizes various Resource Manager operations
KP Kupp Process Startup NO Synchronizes kupp process startup
KT Scheduler Plan NO Synchronizes accesses to the current Resource Manager plan
L Library Cache Lock 1 NO Synchronizes accesses to library cache objects
MD Materialized View Log DDL NO Lock held during materialized view log DDL statements
MH AQ Notification Mail Host NO Lock used for recovery when setting Mail Host for AQ e-mail notifications
ML AQ Notification Mail Port NO Lock used for recovery when setting Mail Port for AQ e-mail notifications
MN LogMiner NO Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
MR Media Recovery NO Lock used to coordinate media recovery with other uses of datafiles
MS Materialized View Refresh Log NO Lock held during materialized view refresh to setup MV log
MW MWIN Schedule NO This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
N Library Cache Pin 1 NO Synchronizes accesses to the contents of library cache objects
OC Outline Cache NO Synchronizes write accesses to the outline cache
OL Outline Name NO Synchronizes accesses to a particular outline name
OQ OLAPI Histories NO Synchronizes access to olapi history resources
PD Property Lock NO Serializes property update
PE Parameter NO Synchronizes system parameter updates
PF Password File NO Synchronizes accesses to the password file
PG Global Parameter NO Synchronizes global system parameter updates
PH AQ Notification Proxy NO Lock used for recovery when setting Proxy for AQ HTTP notifications
PI Remote PX Process Spawn Status NO Communicates remote Parallel Execution Server Process creation status
PL Transportable Tablespace NO Coordinates plug-in operation of transportable tablespaces
PM ASM PST Signalling NO Signals inter-instance access to ASM PST metadata
PR Process Startup NO Synchronizes process startup
PS PX Process Reservation NO Parallel Execution Server Process reservation and synchronization
PT ASM Partnership and Status Table NO Gates inter-node synchronization of ASM PST metadata
PV KSV slave startup NO Synchronizes slave start_shut
Q Row Cache NO Coordinates updates and accesses to row cache objects
RB OSM Rollback Recovery NO Serializes OSM rollback recovery operations
RF Data Guard Broker NO Synchronizes broker lock operation involving lock value
RM GES Resource Remastering NO Coordinates Global Enqueue Service resource remastering
RN Redo Log Nab Computation NO Coordinates nab computations of online logs during recovery
RO Multiple Object Reuse NO Coordinates flushing of multiple objects
RP Resilver / Repair NO Enqueue held when resilvering is needed or when datablock is repaired from mirror
RS Reclaimable Space NO Lock held by a space reclaimable operation to allow other operations to wait for it
RT Redo Thread NO Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
SB LogicalStandby NO Synchronizes Logical Standby metadata operations
SC System Change Number NO Coordinates system change number generation on multiple instances
SF AQ Notification Sender NO Lock used for recovery when setting Sender for AQ e-mail notifications
SH Active Session History Flushing NO To prevent multiple concurrent flushers
SI Streams Table Instantiation NO Prevents muiltiple streams table instantiations
SK Shrink Segment NO Serialize shrink of a segment
SM SMON Serialization NO Lock to check SMON global work in RAC
SQ Sequence Cache NO Lock to ensure that only one process can replenish the sequence cache
SR Synchronized Replication NO Coordinates replication / streams operations
SS Sort Segment NO Ensures that sort segments created during parallel DML operations aren’t prematurely cleaned up
ST Space Transaction NO Synchronizes space management activities in dictionary-managed tablespaces
SU SaveUndo Segment NO Serializes access to SaveUndo Segment
SV Sequence Ordering NO Lock to ensure ordered sequence allocation in RAC mode
SW Suspend Writes NO Coordinates the ‘alter system suspend’ operation
TA Instance Undo NO Serializes operations on undo segments and undo tablespaces
TB SQL Tuning Base Existence Cache NO Synchronizes writes to the SQL Tuning Base Existence Cache
TC Tablespace Checkpoint NO Lock held to guarantee uniqueness of a tablespace checkpoint
TD KTF map table enqueue NO Serializes updates and inserts to the SMON_SCN_TIME mapping table
TE KTF broadcast NO Serializes broadcasts for flushes to SMON_SCN_TIME
TF Temporary File NO Serializes dropping of a temporary file
TL Log Lock NO Serializes threshold log table read and update
TO Temp Object NO Synchronizes DDL and DML operations on a temp object
TQ Queue table enqueue NO Synchronizes access to queue table
TS Temporary Segment NO Serializes accesses to temp segments
TT Tablespace NO Serializes DDL operations on tablespaces
TW Cross-Instance Transaction NO Lock held by one instance to wait for transactions on all instances to finish
UN User Name NO Protects a user name from being dropped during use
US Undo Segment NO Lock held to perform DDL on the undo segment
WA AQ Notification Watermark NO Lock used for recovery when setting Watermark for memory usage in AQ notifications
WF SWRF Flush NO This enqueue is used to serialize the flushing of snapshots
WL Being Written Redo Log NO Coordinates access to redo log files and archive logs
WP SWRF Purge NO This enqueue handles concurrency between purging and baselines
WS LogWriter Standby NO Used by LogWriter to coordinate communication to standby databases
XH AQ Notification No-Proxy NO Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
XR Quiesce / Force Logging NO Lock held during database quiesce or for database force logging
XY Internal Test NO Lock used for internal testing

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You can always retrieve this list for the release you are working on with the following query:

SELECT type, name, is_user, description
FROM V$LOCK_TYPE
ORDER BY is_user desc, type;
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