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DBMS_METADATA

With DBMS_METADATA you can retrieve complete database object definitions (metadata) from the dictionary by specifying:

• The type of object, for example, tables, indexes, or procedures

• Optional selection criteria, such as owner or name

• Optional transformations on the output. By default the output is represented in XML, but callers can specify transformations (into SQL DDL, for example), which are implemented by XSL-T stylesheets stored in the database or externally.

DBMS_METADATA provides the following retrieval interfaces:

• For programmatic use: OPEN, SET_FILTER, SET_COUNT, GET_QUERY, SET_PARSE_ITEM, ADD_TRANSFORM, SET_TRANSFORM_PARAM, FETCH_xxx and CLOSE retrieve multiple objects.

• For browsing: GET_XML and GET_DDL return metadata for a single object and are used in SQL queries and for browsing.

This chapter discusses the following topics:

• Summary of DBMS_METADATA Subprograms

Summary of DBMS_METADATA Subprograms

Table 28-1 DBMS_METADATA Package Subprograms

Subprogram	Description
"OPEN Procedure"	Specifies the type of object to be retrieved, the version of its metadata, and the object model.
"SET_FILTER Procedure"	Specifies restrictions on the objects to be retrieved, for example, the object name or schema.
"SET_COUNT Procedure"	Specifies the maximum number of objects to be retrieved in a single FETCH_xxx call.
"GET_QUERY Procedure"	Returns the text of the queries that are used by FETCH_xxx.
"SET_PARSE_ITEM Procedure"	Enables output parsing by specifying an object attribute to be parsed and returned.
"ADD_TRANSFORM Procedure"	Specifies a transform that FETCH_xxx applies to the XML representation of the retrieved objects.
"SET_TRANSFORM_PARAM Procedure"	Specifies parameters to the XSL-T stylesheet identified by transform_handle.
"FETCH_xxx Procedure"	Returns metadata for objects meeting the criteria established by OPEN, SET_FILTER, SET_COUNT, ADD_TRANSFORM, and so on.
"CLOSE Procedure"	Invalidates the handle returned by OPEN and cleans up the associated state.
"GET_XML and GET_DDL Functions"	Returns the metadata for the specified object as XML or DDL.