|Oracle Text Application Developer's Guide
Part Number A90122-01
Working With a Thesaurus, 5 of 5
Oracle Text supplies a knowledge base for English and French. The supplied knowledge contains the information used to perform theme analysis. Theme analysis includes theme indexing, ABOUT queries, and theme extraction with the CTX_DOC package.
The knowledge base is a hierarchical tree of concepts and categories. It has six main branches:
The supplied knowledge base is like a thesaurus in that it is hierarchical and contains broader term, narrower term, and related term information. As such, you can improve the accuracy of theme analysis by augmenting the knowledge base with your industry-specific thesaurus by linking new terms to existing terms.
"Augmenting Knowledge Base with Custom Thesaurus" in this chapter.
You can also extend theme functionality to other languages by compiling a language-specific thesuarus into a knowledge base.
"Adding a Language-Specific Knowledge Base" in this chapter.
Knowledge bases can be in any single-byte character set. Supplied knowledge bases are in WE8ISO8859P1. You can store an extended knowledge base in another character set such as US7ASCII.
You can extend theme functionality to languages other than English or French by loading your own knowledge base for any single-byte whitespace delimited language, including Spanish.
Theme functionality includes theme indexing, ABOUT queries, theme highlighting, and the generation of themes, gists, and theme summaries with CTX_DOC.
You extend theme functionality by adding a user-defined knowledge base. For example, you can create a Spanish knowledge base from a Spanish thesuarus.
To load your language-specific knowledge base, follow these steps:
ctxkbtc -user ctxsys/ctxsys -name my_lang_thes
This command compiles your language-specific knowledge base from the loaded thesaurus. To use this knowledge base for theme analysis during indexing and ABOUT queries, specify the NLS_LANG language as the THEME_LANGUAGE attribute value for the BASIC_LEXER preference.
The following limitations hold for adding knowledge bases: