Export Parameter : Compress

最新推荐文章于 2025-01-02 10:59:38 发布

转载最新推荐文章于 2025-01-02 10:59:38 发布 · 176 阅读

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#数据库

本文介绍如何通过设置COMPRESS参数来管理表数据的初始扩展，在导出时标记表数据以便在导入时进行合并。默认情况下，COMPRESS=y会在导入时合并数据，减少空间占用。如果指定COMPRESS=n，则使用当前的存储参数。注意，此参数仅在导出时有效。

Specifies how Export and Import manage the initial extent for table data.

The default,COMPRESS=y, causes Export to flag table data for consolidation into one initial extent upon Import. If extent sizes are large (for example, because of thPCTINCREASE parameter), the allocated space will be larger than the space required to hold the data.

If you specifyCOMPRESS=n, Export uses the current storage parameters, includin the values of initial extent size and next extent size. The values of the parameters may be the values specified in theCREATE TABLE orALTER TABLE statements othe values modified by the database system. For example, theNEXT extent size value may be modified if the table grows and if thePCTINCREASE parameter is
nonzero.

Note:you can specify theCOMPRESS parameter only when you
export, not when you import. The Export utility, not the Import
utility, generates the data definitions, including the storage
parameter definitions. Therefore, if you specifyCOMPRESS=y when
you export, you can import the data in consolidated form only.

LOB data is not compressed. For LOB data, values of initial
extent size and next extent size at the time of export are used.

consolidation : 巩固, 合并

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