本文参照oracle11gr2官方文档《Oracle? Database Reference11g Release 2 (11.2)》

队列定义：oracle队列存在共享内存中串行访问数据库资源的锁。它产生于一次回话或者一个事物。

队列查找：在系统数据库词典视图 DBA_LOCK_INTERNAL和DBA_LOCK的Lock_type那一列。

产生原因：oracle资源唯一地标识一个对象,可以被不同的会话实例之间在一个实例(本地资源)或(全球资源)。每个会话试图锁定资源所以就会产生队列

队列名称：(前面是简称，即数据库词典查出的内容，后面是解释)

?BL, Buffer Cache Management

?BR, Backup/Restore

?CF, Controlfile Transaction

?CI, Cross-instance Call Invocation

?CU, Bind Enqueue

?DF, Datafile

?DL, Direct Loader Index Creation

?DM, Database Mount

?DR, Distributed Recovery Process

?DW, SecureFiles

?DX, Distributed Transaction

?FP, File Object

?FS, File Set

?HW, High-Water Lock

?IN, Instance Number

?IR, Instance Recovery

?IS, Instance State

?IV, Library Cache Invalidation

?JI, Enqueue used during AJV snapshot refresh

?JQ, Job Queue

?KK, Redo Log "Kick"

?KP, contention in Oracle Data Pump startup and shutdown processes

?KO, Multiple Object Checkpoint

?L[A-P], Library Cache Lock

?LS, Log Start or Switch

?MM, Mount Definition

?MR, Media Recovery

?N[A-Z], Library Cache Pin

?PE, ALTER SYSTEM SET PARAMETER = VALUE

?PF, Password File

?PI, Parallel Slaves

?PR, Process Startup

?PS, Parallel Slave Synchronization

?Q[A-Z], Row Cache

?RO, Object Reuse

?RT, Redo Thread

?RW, Row Wait

?SC, System Commit Number

?SM, SMON

?SN, Sequence Number

?SQ, Sequence Number Enqueue

?SR, Synchronized Replication

?SS, Sort Segment

?ST, Space Management Transaction

?SV, Sequence Number Value

?TA, Transaction Recovery

?TC, Thread Checkpoint

?TE, Extend Table

?TM, DML Enqueue

?TO, Temporary Table Object Enqueue

?TS, Temporary Segment (also TableSpace)

?TT, Temporary Table

?TX, Transaction

?UL, User-defined Locks

?UN, User Name

?US, Undo Segment, Serialization

?WL, Being Written Redo Log

?XA, Instance Attribute Lock

?XI, Instance Registration Lock

前面有一篇文档用到了队列，当时没做过多得解释，所以专门补充了一下

等待事件：http://blog.csdn.net/jacson_bai/article/details/38323821