This appendix lists Oracle enqueues. Enqueues are shared memory structures (locks) that serialize access to database resources. They can be associated with a session or transaction. Enqueue names are displayed in the LOCK_TYPE
column of the DBA_LOCK
and DBA_LOCK_INTERNAL
data dictionary views.
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BL, Buffer Cache Management
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BR, Backup/Restore
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CF, Controlfile Transaction
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CI, Cross-instance Call Invocation
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CU, Bind Enqueue
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DF, Datafile
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DL, Direct Loader Index Creation
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DM, Database Mount
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DR, Distributed Recovery Process
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DX, Distributed Transaction
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FP, File Object
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FS, File Set
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HW, High-Water Lock
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IN, Instance Number
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IR, Instance Recovery
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IS, Instance State
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IV, Library Cache Invalidation
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JI, Enqueue used during AJV snapshot refresh
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JQ, Job Queue
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KK, Redo Log "Kick"
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KO, Multiple Object Checkpoint
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L[A-P], Library Cache Lock
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LS, Log Start or Switch
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MM, Mount Definition
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MR, Media Recovery
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N[A-Z], Library Cache Pin
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PE, ALTER SYSTEM SET PARAMETER = VALUE
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PF, Password File
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PI, Parallel Slaves
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PR, Process Startup
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PS, Parallel Slave Synchronization
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Q[A-Z], Row Cache
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RO, Object Reuse
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RT, Redo Thread
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RW, Row Wait
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SC, System Commit Number
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SM, SMON
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SN, Sequence Number
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SQ, Sequence Number Enqueue
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SR, Synchronized Replication
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SS, Sort Segment
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ST, Space Management Transaction
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SV, Sequence Number Value
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TA, Transaction Recovery
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TC, Thread Checkpoint
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TE, Extend Table
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TM, DML Enqueue
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TO, Temporary Table Object Enqueue
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TS, Temporary Segment (also TableSpace)
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TT, Temporary Table
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TX, Transaction
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UL, User-defined Locks
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UN, User Name
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US, Undo Segment, Serialization
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WL, Being Written Redo Log
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XA, Instance Attribute Lock
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XI, Instance Registration Lock