Oracle Text Index Types

CONTEXT:
Use this index to build a text retrieval application when your text consists of large coherent documents like MS Word, HTML or plain text.This index type requires CTX_DDL.SYNC_INDEX after DML on base
table.

CTXCAT:
Typically you index small documents or text fragments. Other columns in the base table, such as item names, prices and descriptions can be included in the index to improve mixed query performance. This index automatically updates itself after DML to base table.This index is larger and takes longer to build than a CONTEXT index.The CTXCAT index does not support table and index partitioning, documents services
(highlighting, markup, themes, and gists) or query services (explain, query feedback, and browse words.)

CTXRULE:
Use CTXRULE index to build a document classification or routing application.