Most effecient way to generate XML output

Question

What is the most effecient way to generate XML output using ORACLE.
Presently I am aware of the following:
1)DBMS_XMLQUERY
2)DBMS_XMLGEN
3)SQLX functions
We are using the first 2 in our database to generate hierarchical XML. Once the XML is generated the XML file is ftp'd to a UNIX box. Because of the file size restrictions in our UNIX bix we decided not to transform the XML output into XML Attributes.
The attributes are assigned from an XSLT file and the raw XML file is transformed to a file which has attributes.
My question is:
In the Oracle Database release 9.2 is there a better efficient way to genarate the final XML file with Attributes from the database side without using the XSLT. If yes, please give an example how to do this?
Thank You

Answer 1

In general the SQL/XML publishing functions are the most efficient way..
DBMS_XMLQUERY is a legacy technology imlimented in Java. The main advantage is that it can be run outside the database in the mid-tier is required.
DBMS_XMLGEN is a re-implementation of DBMS_XMLQUERY in 'C' which runs inside the database. In most cases it should be much faster than DBMS_XMLQUERY. It provides some features that are still not availalble in the SQL/XML standard such as the ability to generate XML based on a cursor, and the ability to generate recursive output from a connect by query. It is hoped that future versions of the SQL/XML publishing functions will address these issues.
Both DBMS_XMLGEN and DBMS_XMLQUERY are somewhat limited in terms of generating complex XML documents with multiple levels of nesting.
The SQL/XML publishing functions are the preferred way of generating XML from relational data. THey provide the ability to generate extremely complex XML structures from relation data and provide full control over element / attributes names, levels of nested etc. Future development projects will focus on enhancing the performance and functionality of the SQL/XML publishing functions rather than the PL/SQL packages
In general if you can use SQL/XML publishing functions you should do so.
Does this help....