假设用 SQL*Plus 已经创建了一个用户,并为该用户授权相应的角色和执行 CTX 包的权限。在此基础上,讨论 Oracle 全文检索中的 CO
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假设用 SQL*Plus 已经创建了一个用户,并为该用户授权相应的角色和执行 CTX 包的权限。在此基础上,讨论 Oracle 全文检索中的 CONTEXT 索引。
CONTEXT 索引很适合索引大文档,如 MS Word、HTML,或纯文本。你可以以很多种不同的方式自定义一个 CONTEXT 索引。文档必须被加载在一个文本表中。
CONTEXT 索引不是事务性的。
因此,当你执行插入或更新时,必须用 CTX_DDL.SYNC_INDEX 显示同步索引。
示例1:演示用 2M 内部同步索引。
beginctx_ddl.sync_index('myindex', '2M');end;
示例2:演示用 2M 内存同步 part1 索引分区。
beginctx_ddl.sync_index('myindex', '2M', 'part1');end;
参看 。
CONTEXT 索引的默认行为
下面在 docs 表的 text 列上创建一个名为 myindex 默认 CONTEXT 索引:
CREATE INDEX myindex ON docs(text) INDEXTYPE IS CTXSYS.CONTEXT;
该 SQL 是创建 CONTEXT 索引的最简单形式,没有任何配置。因此,有必要了解 Oracle 数据库在此情况的默认行为。
当使用 CREATE INDEX 没有显示指定参数时,系统对所有国家语言按如下默认动作:

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