Oracle教程 2023-02-24

Oracle 视图 V$SYSTEM_PARAMETER2 官方解释，作用，如何使用详细说明

本站中文解释

Oracle视图V$SYSTEM_PARAMETER2用于查看和修改数据库系统参数，它包含系统参数的名称、数值以及参数的范围等信息。它的内容特别有用，包括表空间、回滚段和实例注册等。

要使用Oracle视图V$SYSTEM_PARAMETER2，首先需要确保你有该Grant权限，可以执行：

GRANT SELECT ON V$SYSTEM_PARAMETER2 TO 用户;

接着，你可以执行一个简单的select来查看系统参数：

SELECT name, value, description, isdefault
FROM V$SYSTEM_PARAMETER2
WHERE name = ‘open_cursors’;

最后，如果要修改系统参数，你可以执行：

EXEC DBMS_SYSTEM.set_int_param_in_session(‘open_cursors’, 1000);

官方英文解释

V$SYSTEM_PARAMETER2 displays information about the initialization parameters that are currently in effect for the instance, with each list parameter value appearing as a row in the view. A new session inherits parameter values from the instance-wide values.

Presenting the list parameter values in this format enables you to quickly determine the values for a list parameter. For example, if a parameter value is a, b, then the V$SYSTEM_PARAMETER view does not tell you if the parameter has two values (both a and b) or one value (a, b). V$SYSTEM_PARAMETER2 makes the distinction between the list parameter values clear.

Column	Datatype	Description
`NUM`	`NUMBER`	Parameter number
`NAME`	`VARCHAR2(80)`	Name of the parameter
`TYPE`	`NUMBER`	Parameter type: `1` – Boolean `2` – String `3` – Integer `4` – Parameter file `5` – Reserved `6` – Big integer
`VALUE`	`VARCHAR2(4000)`	Parameter value
`DISPLAY_VALUE`	`VARCHAR2(4000)`	Parameter value in a user-friendly format. For example, if the `VALUE` column shows the value `262144` for a big integer parameter, then the `DISPLAY_VALUE` column will show the value `256K`.
`ISDEFAULT`	`VARCHAR2(6)`	Indicates whether the parameter is set to the default value (`TRUE`) or the parameter value was specified in the parameter file (`FALSE`)
`ISSES_MODIFIABLE`	`VARCHAR2(5)`	Indicates whether the parameter can be changed with `ALTER SESSION` (`TRUE`) or not (`FALSE`)
`ISSYS_MODIFIABLE`	`VARCHAR2(9)`	Indicates whether the parameter can be changed with `ALTER SYSTEM` and when the change takes effect: `IMMEDIATE` – Parameter can be changed with `ALTER SYSTEM` regardless of the type of parameter file used to start the instance. The change takes effect immediately. `DEFERRED` – Parameter can be changed with `ALTER SYSTEM` regardless of the type of parameter file used to start the instance. The change takes effect in subsequent sessions. `FALSE` – Parameter cannot be changed with `ALTER SYSTEM` unless a server parameter file was used to start the instance. The change takes effect in subsequent instances.
`ISPDB_MODIFIABLE`	`VARCHAR2(5)`	Indicates whether the parameter can be modified on a per-PDB basis (`TRUE`) or not (`FALSE`). In a non-CDB, the value of this column is `NULL`.
`ISINSTANCE_MODIFIABLE`	`VARCHAR2(5)`	For parameters that can be changed with `ALTER SYSTEM`, indicates whether the value of the parameter can be different for every instance (`TRUE`) or whether the parameter must have the same value for all Real Application Clusters instances (`FALSE`). If the `ISSYS_MODIFIABLE` column is `FALSE`, then this column is always `FALSE`.
`ISMODIFIED`	`VARCHAR2(8)`	Indicates how the parameter was modified. If an `ALTER SYSTEM` was performed, the value will be `MODIFIED`.
`ISADJUSTED`	`VARCHAR2(5)`	Indicates whether Oracle adjusted the input value to a more suitable value (for example, the parameter value should be prime, but the user input a non-prime number, so Oracle adjusted the value to the next prime number)
`ISDEPRECATED`	`VARCHAR2(5)`	Indicates whether the parameter has been deprecated (`TRUE`) or not (`FALSE`)
`ISBASIC`	`VARCHAR2(5)`	Indicates whether the parameter is a basic parameter (`TRUE`) or not (`FALSE`)
`DESCRIPTION`	`VARCHAR2(255)`	Description of the parameter
`ORDINAL`	`NUMBER`	Position (ordinal number) of the parameter value. Useful only for parameters whose values are lists of strings.
`UPDATE_COMMENT`	`VARCHAR2(255)`	Comments associated with the most recent update
`HASH`	`NUMBER`	Hash value for the parameter name
`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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