The following considerations apply to indexing a CTXRULE index.
If the SVM_CLASSIFIER classifier is used, then you may use the BASIC_LEXER, CHINESE_LEXER, JAPANESE_LEXER, or KOREAN_MORPH_LEXER lexers. If SVM_CLASSIFIER is not used, only the BASIC_LEXER lexer type may be used for indexing your query set. (See Oracle Text Reference for more on lexer and classifier preferences.)
Filter, memory, datastore, and [no]populate parameters are not applicable to index type CTXRULE.
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 those of 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.