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buffercache和sharedpool详解(之三,sharedpool原理)(四)
2014-11-24 00:12:25 来源: 作者: 【 】 浏览:67
Tags:buffercache sharedpool 详解 之三 原理

10:20:54 scott@felix SQL>SELECT ID,TYPE,NAME,BLOCK_COUNT,ROW_COUNTFROM V$RESULT_CACHE_OBJECTS;

IDTYPE NAME BLOCK_COUNT ROW_COUNT

---------- ------------------------------------------------------------ ----------- ----------

0Dependency SCOTT.FELIX 1 0

1Result select /*+result_cache */ count(*) from 1 1

felix

10:21:19 scott@felix SQL>

V$RESULT_CACHE_OBJECTS displays all theobjects (both cached results and dependencies) and their attributes.

Column

Datatype

Description

ID

NUMBER

Identifier for the cache object (also the ID of the first block)

TYPE

VARCHAR2(10)

Type of the cache object:

  • Result Dependency

STATUS

VARCHAR2(9)

Status of the object:

  • New - Result is still under construction Published - Result is available for use Bypass - Result will be bypassed from use Expired - Result has exceeded expiration time Invalid - Result is no longer available for use

BUCKET_NO

NUMBER

Internal hash bucket for the object

HASH

NUMBER

Hash value for the object

NAME

VARCHAR2(128)

Name (for example, SQL prefix or PL/SQL function name)

NAMESPACE

VARCHAR2(5)

Namespace:

  • SQL PLSQL

CREATION_TIMESTAMP

DATE

Time when the object was created

CREATOR_UID

NUMBER

UID that created the object

DEPEND_COUNT

NUMBER

Number of dependencies (TYPE = Result) or dependents (TYPE = Dependency)

BLOCK_COUNT

NUMBER

Total number of blocks in the cached object

SCN

NUMBER

Build SCN (TYPE = Result) or invalidation SCN (TYPE = Dependency)

COLUMN_COUNT

NUMBER

Number of columns in the cached resultFoot 1

PIN_COUNT

NUMBER

Number of active scans on this resultFootref 1

SCAN_COUNT

NUMBER

Total number of scans initiated on the cached resultFootref 1

ROW_COUNT

NUMBER

Total number of rows in the cached resultFootref 1

ROW_SIZE_MAX

NUMBER

Size of the largest row (in bytes)Footref 1

ROW_SIZE_MIN

NUMBER

Size of the smallest row (in bytes)Footref 1

ROW_SIZE_AVG

NUMBER

Average size of a row (in bytes)Footref 1

BUILD_TIME

NUMBER

Amount of time (in hundredths of a second) it took to build the cached resultFootref 1

LRU_NUMBER

NUMBER

LRU list position (the smaller the value, the more recent the usage)Footref 1

OBJECT_NO

NUMBER

Dictionary object number of the dependency objectFoot 2

INVALIDATIONS

NUMBER

Number of times the object has invalidated its dependentsFootref 2

SPACE_OVERHEAD

NUMBER

Overhead (in bytes) for the resultFootref 1

SPACE_UNUSED

NUMBER

Unused space (in bytes) for the resultFootref 1

CACHE_ID

VARCHAR2(93)

CacheId for the result (object name if it's a dependency)

CACHE_KEY

VARCHAR2(93)

CacheKey for the result (object name if it's a dependency)

DB_LINKFoot 3

VARCHAR2(3)

Possible values:

  • YES: If the result cache object references a remote database object NO: If the result cache object does not reference a remote database object

CHECKSUMFootref 3

NUMBER

Checksum for the result object. The checksum is computed over all the blocks in the result cache object minus the object header.

Footnote 1 These columns are only valid for TYPE = Result; otherwise, they are NULL.

Footnote 2 These columns are only valid for TYPE = Dependency; otherwise, they are NULL.

Footnote 3 This column is available starting with Oracle Database11g Release 2 (11.2.0.4)

Table 7-6 Views and TablesRelated to the Server and Client Result Caches

View/Table

Description

V$RESULT_CACHE_STATISTICS

Lists various serv

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