openGauss每日一练第 20天|全文检索

学习openGauss全文检索

openGauss提供了两种数据类型用于支持全文检索。tsvector类型表示为文本搜索优化的文件格式，tsquery类型表示文本查询

1.用tsvector @@ tsquery和tsquery @@ tsvector完成两个基本文本匹配

SELECT 'a fat cat sat on a mat and ate a fat rat'::tsvector @@ 'cat & rat'::tsquery AS RESULT;
SELECT 'fat & cow'::tsquery @@ 'a fat cat sat on a mat and ate a fat rat'::tsvector AS RESULT;

2.创建表且至少有两个字段的类型为 text类型，在创建索引前进行全文检索

CREATE SCHEMA su;
CREATE TABLE su.test1(id int, body text, title text, last_mod_date date);
INSERT INTO su.test1 VALUES(1, 'China, officially the People''s Republic of China(PRC), located in Asia, is the world''s most populous state.', 'China', '2010-1-1');
INSERT INTO su.test1 VALUES(2, 'America is a rock band, formed in England in 1970 by multi-instrumentalists Dewey Bunnell, Dan Peek, and Gerry Beckley.', 'America', '2010-1-1');
INSERT INTO su.test1 VALUES(3, 'England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west.', 'England','2010-1-1');

–将body字段中包含america的行打印出来

SELECT id, body, title FROM su.test1 WHERE to_tsvector(body) @@ to_tsquery('america');

3.创建GIN索引

CREATE INDEX test1_idx_1 ON su.test1 USING gin(to_tsvector('english', body));
\d+ su.test1

4.清理数据

drop schema su cascade;