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Oracle 视图 V$BH 官方解释，作用，如何使用详细说明

本站中文解释

V$BH试图是使用Oracle的V$系列视图之一，它用于检索某一时刻下数据库系统内放置的所有块号（block）头文件（header）中的信息。它没有入参，可以显示出所有块，当前都发生了什么，以及状态等信息。V$BH是在发生ORA-1578或者ORA-1552错误时非常有用，因为它可以提供块头文件所需要诊断的信息。

使用V$BH可以通过以下步骤实现：

1.连接到Oracle服务器上
2.使用Oracle提供的V$视图，运行查询语句：SELECT * FROM V$BH
3.检查查询结果，检查SQL的活动和状态，以查看所有块是不是正常运行
4.收集出现的问题块的详细信息，并分析，找出问题原因
5.根据分析的结果，执行适当的措施，以修复问题，并确保正常运行数据库系统。

官方英文解释

V$BH displays the status and number of pings for every buffer in the SGA. This is an Oracle Real Application Clusters view.

Column Datatype Description

FILE#

NUMBER

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

BLOCK#

NUMBER

Block number

CLASS#

NUMBER

Class number

STATUS

VARCHAR2(10)

Status of the buffer:

  • cr – Consistent read

  • flashcur – A current flash cache buffer

  • flashfree – A free flash cache buffer

  • free – Not currently in use

  • irec – In instance recovery mode

  • mrec – In media recovery mode

  • pi – A past image in RAC mode

  • pmemfree – A free PMEM buffer

  • pmemcr – pmemcr – A consistent-read/previous version of a PMEM buffer

  • pmemcur – A current PMEM buffer

  • read – Being read from disk

  • scur – Shared current

  • securefile – A secured file buffer

  • xcur – Exclusive

XNC

NUMBER

This column is obsolete. Its value is hard-coded to 0.

FORCED_READS

NUMBER

This column is obsolete. Its value is hard-coded to 0.

FORCED_WRITES

NUMBER

This column is obsolete. Its value is hard-coded to 0.

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

The 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_CLASS

NUMBER

The 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.

DIRTY

VARCHAR2(1)

Y – block modified

TEMP

VARCHAR2(1)

Y – temporary block

PING

VARCHAR2(1)

Y – block pinged

STALE

VARCHAR2(1)

Y – block is stale

DIRECT

VARCHAR2(1)

Y – direct block

NEW

CHAR(1)

Always set to N. This column is obsolete and maintained for backward compatibility.

OBJD

NUMBER

Database object number of the block that the buffer represents

TS#

NUMBER

Tablespace number of block

LOBID

NUMBER

If the buffer belongs to a SecureFiles object, the value in this column is the unique identifier for the SecureFiles object. For other buffer types, the value in this column is meaningless.

CACHEHINT

NUMBER

Numeric representation of the values in the FLASH_CACHE and CELL_FLASH_CACHE columns. See the descriptions and possible values for the FLASH_CACHE and CELL_FLASH_CACHE columns in this view.

FLASH_CACHE

VARCHAR2(7)

Database Smart Flash Cache hint to be used for segment blocks:

  • DEFAULT

  • KEEP

  • NONE

Solaris and Oracle Linux functionality only.

CELL_FLASH_CACHE

VARCHAR2(7)

Cell flash cache hint to be used for segment blocks:

  • DEFAULT

  • KEEP

  • NONE

See Also: Oracle Exadata Storage Server Software documentation for more information

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


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