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Oracle 参数 DB_SECUREFILE 官方解释，作用，如何配置最优化建议

本站中文解释

：

DB_SECUREFILE是Oracle参数，它是一种安全文件存储属性。DB_SECUREFILE=TRUE时，让Oracle确定使用数据库表空间来存储大对象，而不是使用普通文件系统，从而提供更好的安全性。

正确设置此参数的方法：

1. 使用SQL*Plus的“Alter System”命令来设置此参数，如
ALTER SYSTEM SET DB_SECUREFILE=TRUE;

2. 或者可以通过修改“init.ora”文件，在文件末尾添加一行内容：db_securefile=true。修改完成后，要重启数据库，该参数才能生效。

官方英文解释

DB_SECUREFILE specifies whether to treat LOB files as SecureFiles.

Property Description

Parameter type

String

Syntax

DB_SECUREFILE = { NEVER | PERMITTED | PREFERRED | ALWAYS | IGNORE }

Default value

PERMITTED if the COMPATIBLE initialization parameter is set to 11.2.0.1, 11.2.0.2, or 11.2.0.3, or PREFERRED if the COMPATIBLE initialization parameter is set to 12.0.0.0 or higher

Modifiable

ALTER SESSION, ALTER SYSTEM

Modifiable in a PDB

Yes

Basic

No

Values

  • NEVER

    Any LOBs that are specified as SecureFiles are created as BasicFiles LOBs. All SecureFiles-specific storage options and features (for example, compress, encrypt, deduplicate) will cause an exception. The BasicFiles LOB defaults will be used for storage options not specified.

  • PERMITTED

    LOBs are allowed to be created as SecureFiles.

  • PREFERRED

    All LOBs are created as SecureFiles unless BASICFILE is explicitly specified in the LOB storage clause or the tablespace is a Manual Segment Space Management tablespace. When PREFERRED is set, cases where BASICFILE would otherwise be inherited from the partition or column level LOB storage are ignored; the LOBs will be created as SecureFiles instead.

  • ALWAYS

    Attempts to create all LOBs as SecureFiles LOBs but creates any LOBs not in an Automatic Segment Space Managed (ASSM) tablespace as BasicFiles LOBs, unless SECUREFILE is explicitly specified. Any BasicFiles LOB storage options that are specified will be ignored and the SecureFiles LOB defaults will be used for all storage options not specified.

  • IGNORE

    The SECUREFILE keyword and all SecureFiles options are ignored.

If the COMPATIBLE initialization parameter is not set to 11.1.0 or higher, then LOBs are not treated as SecureFiles.

If there is a LOB column with two partitions (one that has a tablespace for which ASSM is enabled and one that has a tablespace for which ASSM is not enabled), then LOBs in the partition with the ASSM-enabled tablespace will be treated as SecureFiles and LOBs in the other partition will be treated as BasicFiles.

If an application is not certified with SecureFiles, the value of the DB_SECUREFILE initialization parameter can be set to PERMITTED to get the default behavior of Oracle Database 11g.

See Also:

Oracle Database
SecureFiles and Large Objects Developer’s
Guide for an example of setting this parameter using the ALTER SYSTEM statement


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