如何理解impdp transform参数

今天就跟大家聊聊有关如何理解impdp transform参数，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。

使用实例

impdp hr TABLES=hr.employees DIRECTORY=dpump_dir1 DUMPFILE=hr_emp.dmp TRANSFORM=STORAGE:n:table
impdp hr DIRECTORY=dpump_dir1 DUMPFILE=hr.dmp SCHEMAS=hr TRANSFORM=SEGMENT_ATTRIBUTES:n

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TRANSFORM

Default: There is no default

Purpose

Enables you to alter object creation DDL for objects being imported.

Syntax and Description

TRANSFORM = transform_name:value[:object_type]

The transform_name specifies the name of the transform. The possible options are as follows:

• SEGMENT_ATTRIBUTES – If the value is specified as y, then segment attributes (physical attributes, storage attributes, tablespaces, and logging) are included, with appropriate DDL. The default is y.

• STORAGE – If the value is specified as y, then the storage clauses are included, with appropriate DDL. The default is y. This parameter is ignored ifSEGMENT_ATTRIBUTES=n.

• OID – If the value is specified as n, then the assignment of the exported OID during the creation of object tables and types is inhibited. Instead, a new OID is assigned. This can be useful for cloning schemas, but does not affect referenced objects. The default value is y.

• PCTSPACE – The value supplied for this transform must be a number greater than zero. It represents the percentage multiplier used to alter extent allocations and the size of data files.

  Note that you can use the PCTSPACE transform with the Data Pump Export SAMPLE parameter so that the size of storage allocations matches the sampled data subset. (See "SAMPLE".)

• SEGMENT_CREATION – If set to y (the default), then this transform causes the SQL SEGMENT CREATION clause to be added to the CREATE TABLE statement. That is, the CREATE TABLE statement will explicitly say either SEGMENT CREATION DEFERRED or SEGMENT CREATION IMMEDIATE. If the value is n, then the SEGMENT CREATION clause is omitted from the CREATE TABLE statement. Set this parameter to n to use the default segment creation attributes for the table(s) being loaded. (This functionality is available starting with Oracle Database 11g release 2 (11.2.0.2).)

The type of value specified depends on the transform used. Boolean values (y/n) are required for the SEGMENT_ATTRIBUTES, STORAGE, and OID transforms. Integer values are required for the PCTSPACE transform.

The object_type is optional. If supplied, it designates the object type to which the transform will be applied. If no object type is specified, then the transform applies to all valid object types. The valid object types for each transform are shown in Table 3-1.

Table 3-1 Valid Object Types For the Data Pump Import TRANSFORM Parameter

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