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Oracle 视图 V$CACHE_LOCK 官方解释，作用，如何使用详细说明

本站中文解释

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V$CACHE_LOCK_DATA视图可以提供缓存中锁定数据的信息，帮助用户识别存在的锁定，确定锁定的原因及影响。

V$CACHE_LOCK_DATA视图主要涉及以下几列：

ADDR : 指向锁定数据的指针地址；
HASH_VALUE : 用来计算缓存锁的唯一散列值；
KADDR1、KADDR2 : 指向两个锁定持有者的指针地址；
REQUEST : 指定数据库锁的请求模式；
TYPE : 指定数据库锁的类型；
SID : 会话ID，持有该锁的会话编号；
SERIAL# : 序列号，关联的会话的事务号。

如果要使用V$CACHE_LOCK_DATA视图，必须拥有全局以及调试资格(SELECT ANY DICTIONARY系统权限)，并且赋予V$SESSION_LONGOPS视图，V$SESSION视图，V$SESSION_WAIT视图的权限。此外，该视图只能由SYSDBA用户查询，因此，用户必须拥有这种权限。

使用V$CACHE_LOCK_DATA视图前，可以通过V$CACHE_LOCK_DATA动态性能视图，来查询缓存中锁定数据的资源数据，从而识别并分析存在的锁定，有助于确定锁定的原因及影响，从而帮助应用程序的优化。

官方英文解释

V$CACHE_LOCK is deprecated. The information that was provided in this view is now provided in the V$INSTANCE_CACHE_TRANSFER and V$SEGMENT_STATISTICS views.

Column Datatype Description

FILE#

NUMBER

Data file identifier number (to find file name, query DBA_DATA_FILES or V$DBFILE)

BLOCK#

NUMBER

Block number

STATUS

VARCHAR2(10)

Status of the block:

  • free – Not currently in use

  • xcur – Exclusive

  • scur – Shared current

  • cr – Consistent read

  • read – Being read from disk

  • mrec – In media recovery mode

  • irec – In instance recovery mode

XNC

NUMBER

Number of parallel cache management (PCM) lock conversions due to contention with another instance

FORCED_READS

NUMBER

Number of times the block had to be reread from the cache because another instance has forced it out of this instance’s cache by requesting the lock on the block in exclusive mode

FORCED_WRITES

NUMBER

Number of times GCS had to write this block to cache because this instance had used the block and another instance had requested the lock on the block in a conflicting mode

NAME

VARCHAR2(128)

Name of the database object containing the block

KIND

VARCHAR2(15)

Type of database object:

  • 1 – Index

  • 2 – Table

  • 3 – Cluster

  • 4 – View

  • 5 – Synonym

  • 6 – Sequence

  • 7 – Procedure

  • 8 – Function

  • 9 – Package

  • 10 – Nonexistent

  • 11 – Package body

  • 12 – Trigger

  • 13 – Type

  • 14 – Type body

  • 19 – Table partition

  • 20 – Index partition

  • 21 – LOB

  • 22 – Library

  • Null – Unknown

OWNER#

NUMBER

Owner number

LOCK_ELEMENT_ADDR

RAW(4 | 8)

Address of the lock element that contains the PCM lock that is covering the buffer. If more than one buffer has the same address, then these buffers are covered by the same PCM lock.

LOCK_ELEMENT_NAME

NUMBER

Address of the lock element that contains the PCM lock that is covering the buffer. If more than one buffer has the same address, then these buffers are covered by the same PCM lock.

INDX

NUMBER

Platform-specific lock manager identifier

CLASS

NUMBER

Platform-specific lock manager identifier

CON_ID

NUMBER

The ID of the container to which the data pertains. Possible values include:

  • 0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.

  • 1: This value is used for rows containing data that pertain to only the root

  • n: Where n is the applicable container ID for the rows containing data


数据运维技术 » Oracle 视图 V$CACHE_LOCK 官方解释，作用，如何使用详细说明
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