Oracle教程 2023-03-20

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

本站中文解释

_STATISTICS视图

V$BUFFER_POOL_STATISTICS视图提供了缓冲池统计信息。它包括三列：name，value和statistic，它们表示缓冲池的名称，相应值和相应统计。查看该视图可以用于衡量当前的缓冲池的使用情况和性能，大部分的信息反映了相应的缓冲池的总量，平均值，高水位情况及其他实时统计信息。

使用方法：

可以使用SELECT命令来查询该视图：

SELECT *
FROM v$buffer_pool_statistics;

更多的，可以选择聚合语句来查询缓冲池统计信息，比如：

SELECT name, SUM(value) as TOTAL
FROM v$buffer_pool_statistics
GROUP BY name;

这将把缓冲池中统计数据按名称汇总。

官方英文解释

V$BUFFER_POOL displays information about all buffer pools available for the instance.

Column	Datatype	Description
`ID`	`NUMBER`	Buffer pool identifier number
`NAME`	`VARCHAR2(20)`	Name of the buffer pool: `DEFAULT` `KEEP` `RECYCLE` Note: Currently, `KEEP` and `RECYCLE` pools only exist for the standard block size. All nonstandard block size pools are `DEFAULT`.
`BLOCK_SIZE`	`NUMBER`	Block size (in bytes) for buffers in this pool. Possible values: the standard block size, the power of 2 nonstandard block sizes, `2048`, `4096`, `8192`, `16384`, `32768`.
`RESIZE_STATE`	`VARCHAR2(10)`	Current state of the resize operation: `STATIC` – Not being resized `ALLOCATING` – Memory is being allocated (can be canceled by the user) `ACTIVATING` – New buffers are being created (user cannot cancel) `SHRINKING` – Buffers are being deleted (can be canceled by the user)
`CURRENT_SIZE`	`NUMBER`	Present size of the sub-cache (in megabytes)
`BUFFERS`	`NUMBER`	Current instantaneous number of buffers
`TARGET_SIZE`	`NUMBER`	If a resize is in progress (state is not `STATIC`), records new target size (in megabytes). If the pool is `STATIC`, the value in this column is the same as the current size of the pool.
`TARGET_BUFFERS`	`NUMBER`	If a resize is in progress, records new target size in terms of buffers. Otherwise, the value in this column is the same as the current number of buffers.
`PREV_SIZE`	`NUMBER`	Previous buffer pool size. If the buffer pool has never been resized, the previous size is zero.
`PREV_BUFFERS`	`NUMBER`	Previous number of buffers in the buffer pool. Value is zero if the buffer pool has never been resized.
`LO_BNUM`	`NUMBER`	Obsolete column
`HI_BNUM`	`NUMBER`	Obsolete column
`LO_SETID`	`NUMBER`	Obsolete column
`HI_SETID`	`NUMBER`	Obsolete column
`SET_COUNT`	`NUMBER`	Obsolete column
`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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