Create a Section Group

You enable section searching by defining section groups. Use one of the system-defined section groups to create an instance of a section group.

You use section groups to specify the type of document set that you have and implicitly indicate the tag structure. Choose a section group that is appropriate for your document collection. For instance, to index HTML tagged documents, use HTML_SECTION_GROUP. Likewise, to index XML tagged documents, use XML_SECTION_GROUP.

Table 1 Types of Section Groups

Section Group Preference	Description
NULL_SECTION_GROUP	This is the default. Use this group type when you define no sections or when you define only SENTENCE or PARAGRAPH sections.
BASIC_SECTION_GROUP	Use this group type for defining sections where the start and end tags are of the form <A> and </A>. Note: This group type does not support input such as unbalanced parentheses, comments tags, and attributes. Use HTML_SECTION_GROUP for this type of input.
HTML_SECTION_GROUP	Use this group type to index HTML documents and for defining sections in HTML documents.
XML_SECTION_GROUP	Use this group type to index XML documents and for defining sections in XML documents.
AUTO_SECTION_GROUP	Use this group type to automatically create a zone section for each start-tag/end-tag pair in an XML document. As in XML, the section names derived from XML tags are case-sensitive. Attribute sections are created automatically for XML tags that have attributes. Attribute sections are named in the form tag@attribute. Stop sections, empty tags, processing instructions, and comments are not indexed. The following limitations apply to automatic section groups: You cannot add zone, field, or special sections to an automatic section group. Automatic sectioning does not index XML document types (root elements.) The length of the indexed tags, including prefix and namespace, cannot exceed 64 bytes. Tags longer than 64 bytes are not indexed.
PATH_SECTION_GROUP	Use this group type to index XML documents. This preference behaves like AUTO_SECTION_GROUP. The difference is that you can search paths with the INPATH and HASPATH operators. Queries are also case-sensitive for tag and attribute names.
NEWS_SECTION_GROUP	Use this group to define sections in newsgroup-formatted documents according to RFC 1036.

Notes

• Documents sent to the HTML, XML, AUTO, and PATH sectioners must begin with \s*<. The \s* represents zero or more whitespace characters. Otherwise, the document is treated as a plain-text document, and no sections are recognized.

• Do not use left-angle-brackets within a section data. If a left-angle-bracket is followed by a non-blank character, then the section parser treats the free text (between the left-angle and right-angle brackets) as a tag name.

  For example:

  <DOCUMENT> <BODYTEXT> ABC < R1 NOMISS <R2 MISSED1 </BODYTEXT> <FIELDS> DEF <R3 MISSED2 </FIELDS> </DOCUMENT> GHI FALSEPOSITIVE JKL

  In the preceding example, the section parser treats R2 MISSED1 </BODYTEXT and R3 MISSED2 </FIELDS as tag names. This may result in false-positive hits or missed hits, which may cause the following issues:

  • Any word in the R2 MISSED1 </BODYTEXT and R3 MISSED2 </FIELDS phrases are not searchable within a section.

  • Any text outside a section, such as GHI, FALSEPOSITIVE, and JKL are wrongly included in a section if it is not closed.

• You use the CTX_DDL package to create section groups and define sections as part of section groups. For example, to index HTML documents, create a section group with HTML_SECTION_GROUP:

  begin ctx_ddl.create_section_group('htmgroup', 'HTML_SECTION_GROUP'); end;

• Starting with Oracle Database 18c, use of NEWS_SECTION_GROUP is deprecated in Oracle Text. Use external processing instead.

  If you want to index USENET posts, then preprocess the posts to use BASIC_SECTION_GROUP or HTML_SECTION_GROUP within Oracle Text. USENET is rarely used commercially.