Publishing Reports to the Web - Downloads - Oracle

Methodology
20.1.2.1 Non-SQL Data Sources
To publish data from any data source use the pluggable data source architecture in
Oracle Reports. Out-of-the-box Oracle Reports supports non-SQL data sources, such as
the XML, Text, and JDBC pluggable data sources. Both XML and Text pluggable data
sources can be accessed through a remote URL (even across firewalls). If speed is a
concern, download the data locally and use the local data stream rather than a remote
URL. You can also specify the domains for which you can bypass a proxy server.
The XML pluggable data source supports runtime XML data validation. Select the
Validate Data Source check box in the XML query wizard to activate runtime XML data
validation. Selecting Validate Data Source ensures that the XML data is verified as it is
fetched against the data definition specified in the DTD or in the XML schema. This is
a very costly operation and proves to be useful only when you develop the report and
not during production. You will see a noticeable performance difference when the
XML data stream is very large.
You can specify either an XML schema or a DTD schema for the data definition. An
XML schema forces type checking. Whereas, a DTD schema does not require type
checking as all data is treated as strings.
Note: Ensure that the data types of the non-SQL sources match —
columnwise.
You can also specify an extensible style sheet language (XSL) file for the XML data
stream to convert it from any format into a simple row set/row data feed. It is better to
have data in the correct format to start with, unless you need to apply the XSL at run
time.
Pluggable Text data sources support the use of cell wrappers. This causes the file
format level delimiter to be ignored for every field that has a wrapper defined. Avoid
using cell wrappers unless really required.
The JDBC pluggable data source supports JDBC bridges, as well as, thick and thin
JDBC drivers. Selecting the driver directly impacts the fetching of data. The choice
depends on the application and the database being used. Using a native driver
generally results in better performance.
20.1.2.2 Database Indexes
Columns used in a SQL WHERE clause should be indexed. The impact of indexes used
on columns in the master queries of a report are minor, as these queries access the
database once. To improve performance significantly, indexes should be used on any
linked columns in the detail query.
Note: Lack of appropriate indexes can result in many full-table
scans and slows down performance.
20.1.2.3 Calculations
Within a report (either through summary or formula columns) ensure that most of the
calculations are performed by the data source. In case of SQL queries, calculations are
performed on the database rather than on the data retrieved by the report.
User-defined functions and procedures stored by the database can also be included in
the query select list of an Oracle9i or a JDBC query. This is more efficient than using a
local function, since the calculated data is returned as part of the result set from the
database.
Tuning Oracle Reports 20-9