Oracle Text索引概述

Classification: Oracle Text domain index and composite domain index of type CONTEXT, CTXCAT, CTXRULE, orCTXXPATH.  
        A composite domain index (CDI) is an Oracle Text index that not only indexes and processes a specified text column, but also indexes and processes FILTER BY and ORDER BY structured columns, which are specified during index creation.

CONTEXT

A CONTEXT index is useful when your source text consists of many large, coherent documents.

This index requires manual synchronization after DML. 

CREATE INDEX [schema.]index ON [schema.]table(txt_column)  INDEXTYPE IS ctxsys.context [ONLINE]  [FILTER BY filter_column[, filter_column]...]  [ORDER BY oby_column[desc|asc][, oby_column[desc|asc]]...]  [LOCAL [(PARTITION [partition] [PARAMETERS('paramstring')]

[, PARTITION [partition] [PARAMETERS('paramstring')]])]

[PARAMETERS(paramstring)] [PARALLEL n] [UNUSABLE]];

paramstring = 
'[DATASTORE datastore_pref]  [FILTER filter_pref]  [CHARSET COLUMN charset_column_name]   [FORMAT COLUMN format_column_name] [LEXER lexer_pref] [LANGUAGE COLUMN language_column_name]  [WORDLIST wordlist_pref]  [STORAGE storage_pref]  [STOPLIST stoplist]  [SECTION GROUP section_group] [MEMORY memsize] [POPULATE | NOPOPULATE] [SYNC (MANUAL | EVERY "interval-string" | ON COMMIT)] [TRANSACTIONAL]'
如：
CREATE INDEX tdrmauto02x ON tdrmauto02(text)   INDEXTYPE IS CTXSYS.CONTEXT local   (PARTITION tdrm02x_i1 PARAMETERS('   MEMORY 20m SYNC(ON COMMIT)'),   PARTITION tdrm02x_i2,   PARTITION tdrm02x_i3)  PARAMETERS('   SYNC (EVERY "NEXT_DAY(TRUNC(SYSDATE), ''MONDAY'') + 15/24")  ');
手工维护：execute CTL_DDL.SYNC_INDEX('REVIEW_CONTEXT_INDEX');
自动维护：设定提交时或在指定时间间隔内自动维护
CTXCAT 

This index is transactional, automatically updating itself with DML to the base table

CTXXPATH

The CTXPATH index is used to speed up   existsNode()  queries on an XMLType column