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Oracle® XML DB Developer's Guide
12c Release 1 (12.1)

E17603-09
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36 Exporting and Importing Oracle XML DB Data

This chapter describes how you can use Oracle Data Pump to export and import XMLType tables for use with Oracle XML DB.

Note:

You can use the older export and import utilities exp and imp to migrate data to database releases that are prior to Oracle Database 11g. However, these older utilities do not support using XMLType data that is stored as binary XML.

This chapter discusses the following topics:

Exporting and Importing XMLType Tables

Oracle Data Pump enables high-speed movement of data and metadata from one database to another. There are two modes for using Oracle Data Pump: transportable tablespaces mode and non-transportable tablespaces mode. For the transportable tablespaces mode there is this restriction regarding XMLType data: you cannot change the XMLType storage model.

As with other database objects, XML data is exported in the character set of the exporting server. During import, the data is converted to the character set of the importing server.

Oracle Data Pump has two command-line clients, expdp and impdp, that invoke Data Pump Export utility and Data Pump Import utility, respectively. The expdp and impdp clients use procedures provided in PL/SQL package DBMS_DATAPUMP to execute export and import commands, passing the parameters entered at the command-line. These parameters enable the exporting and importing of data and metadata for a complete database or subsets of a database.

The Data Pump Export and Import utilities (invoked with commands expdp and impdp, respectively) have a similar look and feel to the original Export (exp) and Import (imp) utilities, but they are completely separate.

Data Pump Export utility (invoked with expdp) unloads data and metadata into a set of operating system files called a dump file set. The dump file set can be imported only by the Data Pump Import utility (invoked using impdp).

Oracle XML DB supports export and import of XMLType tables and columns that store XML data, whether it is XML schema-based or not.

If a table is XML schema-based, then it depends on the XML schema used to define its data. This XML schema can also have dependencies on SQL object types that are used to store the data, in the case of object-relational storage. Therefore, exporting a user who has XML schema-based XMLType tables also exports the following:

  • SQL objects types (if object-relational storage was used)

  • XML schemas

  • XML tables

You can export and import this data regardless of the XMLType storage format (object-relational or binary XML). However, Oracle Data Pump exports and imports XML data as text or binary XML data only. The underlying tables and columns used for object-relational storage of XMLType are thus not exported. Instead, they are converted to binary form and then exported as self-describing binary XML data.

Note:

Oracle Data Pump for Oracle Database 11g Release 1 (11.1) does not support the export of XML schemas, XML schema-based XMLType columns, or binary XML data to database releases prior to 11.1.

Regardless of the XMLType storage model, the format of the dump file is either text or self-describing binary XML with a token map preamble. By default, self-describing binary XML is used.

How Oracle Data Pump stores this data in the dump file depends on the value of the export parameter, data_options (the only valid value for this parameter is xml_clobs.) If you specify this value on the export command line then all XMLType data is stored in text format in the dump file. Otherwise, the dump file uses binary XML.

Since XMLType data is exported and imported as XML data, the source and target databases can use different XMLType storage models for that data. You can export data from a database that stores XMLType data one way and import it into a database that stores XMLType data a different way.

Note:

Do not use option table_exists_action=append to import more than once from the same dump file into an XMLType table, regardless of the XMLType storage model used. Doing so raises a unique-constraint violation error because rows in XMLType tables are always exported and imported using a unique object identifier.

See Oracle Database Utilities for information about table_exists_action.

Export/Import Limitations for Oracle XML DB Repository

You can export and import the XMLType tables that store the XML data for Oracle XML DB Repository resources that are based on a registered XML schema.

However, only the XML data is exported. The repository structure, that is, the relationships in the foldering hierarchy, are lost during export. The row-level security (RLS) policies and path-index triggers are not exported for hierarchy-enabled tables. When these tables are imported, they are not hierarchy-enabled.

Export/Import Syntax and Examples

Export and import using Oracle Data Pump is described in Oracle Database Utilities. This section includes additional guidelines and examples for using commands expdp and impdp with XMLType data.

The examples presented here use the command-line commands expdp and impdp. After submitting such a command with a user name and command parameters, you are prompted for a password. The examples here do not show this prompting.

Performing a Table-Mode Export /Import

An XMLType table has a dependency on the XML schema that was used to define it. Similarly, the XML schema has dependencies on the SQL object types created or specified for it. Importing an XMLType table requires the existence of the XML schema and the SQL object types. When a TABLE mode export is used, only the table related metadata and data are exported. To be able to import this data successfully, the user needs to ensure that both the XML schema and object types have been created.

The examples here assume that you are using a database with the following features:

  • A database with schema user23

  • A table user23.tab41 with an XMLType column stored as binary XML

  • A directory object dpump_dir, for which READ and WRITE privileges have been granted to the user running expdp or impdp

Example 36-1 shows a table-mode export, specified using the TABLES parameter. It exports table tab41 to dump file tab41.dmp.

Example 36-1 Exporting XMLType Data in TABLE Mode

expdp system directory=dpump_dir dumpfile=tab41.dmp tables=user23.tab41 

Note:

In table mode, if you do not specify a schema prefix in the expdp command then the schema of the exporter is used by default.

Example 36-2 shows a table-mode import. It imports table tab41 from dump file tab41.dmp.

Example 36-2 Importing XMLType Data in TABLE Mode

impdp system tables=user23.tab41 directory=dpump_dir dumpfile=tab41.dmp table_exists_action=append

If a table named tab41 already exists at the time of the import then specifying table_exists_action = append causes rows to be appended to that table. Whenever you use parameter value append the data is loaded into new space; existing space is never reused. For this reason you might need to compress your data after the load operation.

See Also:

Oracle Database Utilities, for more information about Oracle Data Pump and its command-line clients, expdp and impdp

Performing a Schema-Mode Export/Import

When performing a Schema mode export, if you have role EXP_FULL_DATABASE, then you can export a database schema, the database schema definition, and the system grants and privileges of that database schema.

The example here assumes that you are using a database with the following features:

  • User x4a has created a table po2.

  • User x4a has a registered XML schema, ipo, which created two ordered collection tables item_oct2 and sitem_nt2.

User x4a creates table po2 as shown in Example 36-3.

Example 36-3 Creating Table po2

CREATE TABLE po2 (po XMLType)
  XMLTYPE COLUMN po
  XMLSCHEMA "ipo.xsd"
  ELEMENT "purchaseOrder"
  VARRAY po.XMLDATA."items"."item"
    STORE AS TABLE item_oct2 ((PRIMARY KEY(NESTED_TABLE_ID, SYS_NC_ARRAY_INDEX$)))
      NESTED TABLE po.XMLDATA."shippedItems"."item" STORE AS sitem_nt2;

Table po2 is then populated and exported, as shown in Example 36-4.

Example 36-4 Exporting XMLType Data in SCHEMA Mode

expdp x4a directory=tkxm_xmldir dumpfile=x4a.dmp

Example 36-4 exports all of the following:

  • All data types that were generated during registration of XML schema ipo.

  • XML schema ipo.

  • Table po2 and the ordered collection tables item_oct2 and sitem_nt2, which were generated during registration of XML schema ipo.

  • All data in all of those tables.

Example 36-5 Importing XMLType Data in SCHEMA Mode

impdp x4a directory=tkxm_xmldir dumpfile=x4a.dmp

Example 36-5 imports all of the data in x4a.dmp to another database, in which the user x4a already exists.

Example 36-6 does the same thing as Example 36-5, but it also remaps the database schema from user x4a to user quine.

Example 36-6 Importing XMLType Data in SCHEMA Mode, Remapping Schema

impdp x4a directory=tkxm_xmldir dumpfile=x4a.dmp remap_schema=x4a:quine

Example 36-6 imports all of the data in x4a.dmp (exported from the database schema of user x4a) into database schema quine. To remap the database schema, user x4a must have been granted role IMP_FULL_DATABASE on the local database and role EXP_FULL_DATABASE on the source database. REMAP_SCHEMA loads all of the objects from the source schema into the target schema.