如何使用Oracle全文检索功能

　　本文简要说明全文检索功能的使用，不做太多的具体说明。
仅供参考使用方法。
1.授权
对具体使用全文检索的用户授权.
$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - ProdUCtion on Sun May 15 20:00:10 2005 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. Connected to: Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production With the Partitioning, OLAP and Oracle Data Mining options JServer Release 9.2.0.4.0 - Production SQL> grant ctxapp to club; Grant succeeded. SQL> connect ctxsys/passWord Connected. SQL> grant execute on ctx_ddl to club; Grant succeeded.
2.使用应用用户连接
创建域索引
SQL> connect club/password Connected. SQL> begin ctx_ddl.create_preference('club_lexer','chinese_vgram_lexer'); end; 2 / PL/SQL procedure successfully completed. Elapsed: 00:00:00.03 SQL> create index id_cont_msg 2 on jivemessage ( SUBJECT ) indextype is ctxsys.context parameters
('lexer club_lexer'); Index created. Elapsed: 00:01:22.42 SQL> select count(*) from jivemessage where contains(subject,'幸福')>0; COUNT(*) ---------- 1847 Elapsed: 00:00:00.17 SQL> select count(*) from jivemessage where subject like '%幸福%'; COUNT(*) ---------- 1841 Elapsed: 00:00:02.89
3.检索比较
以下是一个全文检索的示例，我们检索'abc'，那么全文检索可以把包含'abc'的任何变化组合都查询出来，包括大小写、全半角，而假如用单纯的SQL实现同样的结果，则需要多次like之后union all，其性能差距是不可想象的。
全文检索在类似文本模糊查询上具有极大的优势。当然也可能存在问题，即词法分析器是否准确，会否漏掉部分内容等。
总的说来，满足需求的技术就是好的技术，是否使用一项技术应该通过实践来检验.
SQL> select subject from jivemessage where contains(subject,'abc') >0; SUBJECT -------------------------------------------------------------------------------- 【游戏】把你的名字的首字母用智能ABC打出，看能出来什么？游戏——把你的名字首字母用智能ABC打出来智能ABC暗藏杀机 ABC ABC ABC ABC ABC ＡＢＣ哈哇abc abc SUBJECT -------------------------------------------------------------------------------- abc ABC 振奋爱的激情方案ABC 智能ABC的错吗？ ABC全选瓜果美容ABC 经典英文歌曲ABC，不好你拿版砖砍我，好就回帖顶一下！初夜abc Re: abc Re: abc Re: abc SUBJECT -------------------------------------------------------------------------------- abc 测试发贴""abc abc 25 rows selected. Elapsed: 00:00:00.04
3.定时优化同步域索引
创建定时任务，定期优化和同步域索引
SQL> create or replace procedure hsp_sync_index as 2 begin 3 ctx_ddl.sync_index('id_cont_msg'); 4 end; 5 / Procedure created. Elapsed: 00:00:00.08 SQL> VARIABLE jobno number; SQL> BEGIN 2 DBMS_JOB.SUBMIT(:jobno,'hsp_sync_index();', 3 SYSDATE, 'SYSDATE + (1/24/4)');
4 commit; 5 END; 6 / PL/SQL procedure successfully completed. Elapsed: 00:00:00.27 SQL> create or replace procedure hsp_optimize_index as 2 begin 3 ctx_ddl.optimize_index('id_cont_msg','FULL'); 4 end; 5 / SQL> VARIABLE jobno number; SQL> BEGIN 2 DBMS_JOB.SUBMIT(:jobno,'hsp_optimize_index();', 3 SYSDATE, 'SYSDATE + 1'); 4 commit; 5 END; 6 / Procedure created. Elapsed: 00:00:00.03 PL/SQL procedure successfully completed. Elapsed: 00:00:00.02 SQL>
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