CTXRULE Parameters and Limitations

The following considerations apply to indexing a CTXRULE index:

• If you use the SVM_CLASSIFIER classifier, then you may use the BASIC_LEXER, CHINESE_LEXER, JAPANESE_LEXER, or KOREAN_MORPH_LEXER lexers. If you do not use SVM_CLASSIFIER, then you can use only the BASIC_LEXER lexer type to index your query set.

• Filter, memory, datastore, and [no]populate parameters are not applicable to the CTXRULE index type.

• The CREATE INDEX storage clause is supported for creating the index on the queries.

• Wordlists are supported for stemming operations on your query set.

• Queries for CTXRULE are similar to the CONTAINS queries. Basic phrasing (“dog house”) is supported, as are the following CONTAINS operators: ABOUT, AND, NEAR, NOT, OR, STEM, WITHIN, and THESAURUS. Section groups are supported for using the MATCHES operator to classify documents. Field sections are also supported; however, CTXRULE does not directly support field queries, so you must use a query rewrite on a CONTEXT query.

• You must drop the CTXRULE index before exporting or downgrading the database.

See Also:

• Oracle Text Reference for more information on lexer and classifier preferences

• “Creating a CTXRULE Index”