Filter Types

Use the filter types to create preferences that determine how text is filtered for indexing. Filters enable word processor documents, formatted documents, plain text, HTML, and XML documents to be indexed.

For formatted documents, Oracle Text stores documents in their native format and uses filters to build interim plain text or HTML versions of the documents. Oracle Text indexes the words derived from the plain text or HTML version of the formatted document.

To create a filter preference, you must use one of the filter types shown in Table 2-10.

Table 10 Filter Types

Filter	When Used
AUTO_FILTER	Auto filter for filtering formatted documents.
NULL_FILTER	No filtering required. Use for indexing plain text, HTML, or XML documents.
MAIL_FILTER	Use the MAIL_FILTER to transform RFC-822, RFC-2045 messages in to text that can be indexed.
USER_FILTER	User-defined external filter to be used for custom filtering.
PROCEDURE_FILTER	User-defined stored procedure filter to be used for custom filtering.