Oracle 视图 V$RESULT_CACHE_OBJECTS 官方解释,作用,如何使用详细说明
本站中文解释
Oracle视图V$RESULT_CACHE_OBJECTS可以检索保存在结果缓存中的对象信息。结果缓存是Oracle数据库11gR2之后引入的一种新的功能,用于改进SQL查询的效率。该视图具有如下几列:
* OWNER:对象拥有者的名称
* NAMESPACE:当前对象的空间标示符
* NAME:对象的名称
* SUBNAMESPACE:对象的子空间标识符
* TYPE:对象的类型
* CLASS_LEVEL:对象的类型
* FAST_LOOKUP_ENABLED:指示是否启用快速查找标志
* SHARE_LEVEL:指示这个对象是否可以被共享
* USES:当前查询缓存对象使用的次数
* PING_TIME:这个对象在上次使用后经过的时间
使用V$RESULT_CACHE_OBJECTS,可以运行下列查询来获取具有快速查找的对象的列表:
“`
SELECT owner, namespace, name
FROM V$RESULT_CACHE_OBJECTS
WHERE fast_lookup_enabled = ‘Y’
ORDER BY owner, namespace, name;
“`
官方英文解释
V$RESULT_CACHE_OBJECTS
displays all the objects (both cached results and dependencies) and their attributes.
Column | Datatype | Description |
---|---|---|
|
| Identifier for the cache object (also the ID of the first block) |
|
| Type of the cache object:
|
|
| Status of the object:
|
|
| Internal hash bucket for the object |
|
| Hash value for the object |
|
| Name (for example, SQL prefix or PL/SQL function name) |
|
| Namespace:
|
|
| Time when the object was created |
|
| UID that created the object |
|
| Number of dependencies ( |
|
| Total number of blocks in the cached object |
|
| Build SCN ( |
|
| Number of columns in the cached result |
|
| Number of active scans on this result |
|
| Total number of scans initiated on the cached result |
|
| Total number of rows in the cached result |
|
| Size of the largest row (in bytes) |
|
| Size of the smallest row (in bytes) |
|
| Average size of a row (in bytes) |
|
| Amount of time (in hundredths of a second) it took to build the cached result |
|
| LRU list position (the larger the value, the more recent the usage) |
|
| Dictionary object number of the dependency object |
|
| Number of times the object has invalidated its dependents |
|
| Overhead (in bytes) for the result |
|
| Unused space (in bytes) for the result |
|
|
|
|
|
|
|
| Checksum for the result object. The checksum is computed over all the blocks in the result cache object minus the object header. |
|
| Shows the edition’s object ID that was in use when the result was calculated |
|
| Possible values:
|
|
| Possible values:
|
|
| Subcache ID |
|
| The ID of the container to which the data pertains. Possible values include:
|
Footnote 1
This column is valid only for TYPE
= Result
; otherwise, its value is NULL.
Footnote 2
This column is valid only for TYPE
= Dependency
; otherwise, its value is NULL.
Footnote 3 This column is available starting with Oracle Database 21c.
标签:对象,缓存,视图,指示,快速查找