openGauss每日一练（全文检索）

openGauss 每日一练（全文检索）
本文出处：https://www.modb.pro/db/224179

学习目标
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

课后作业
1.用 tsvector @@ tsquery 和 tsquery @@ tsvector 完成两个基本文本匹配
omm=# SELECT 'a fat cat sat on a mat and ate a fat rat'::tsvector @@ 'cat & rat'::tsquery AS RESULT;
result

t
(1 row)

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

f
(1 row)

omm=#
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
omm=# CREATE SCHEMA tsearch;
CREATE TABLE tsearch.pgweb(id int, body text, title text, last_mod_date date);
CREATE SCHEMA
omm=# CREATE TABLE tsearch.pgweb(id int, body text, title text, last_mod_date date);
INSERT INTO tsearch.pgweb 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');
CREATE TABLE
omm=# INSERT INTO tsearch.pgweb 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 tsearch.pgweb 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 0 1
omm=# INSERT INTO tsearch.pgweb 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 0 1
omm=# INSERT INTO tsearch.pgweb 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');
INSERT 0 1
omm=#
omm=# SELECT id, body, title FROM tsearch.pgweb WHERE to_tsvector(body) @@ to_tsquery('america');

id | body | title
----+-------------------------------------------------------------------------------------------------------------------------+---------
2 | America is a rock band, formed in England in 1970 by multi-instrumentalists Dewey Bunnell, Dan Peek, and Gerry Beckley. | America
(1 row)

omm=#
3.创建 GIN 索引
omm=# CREATE INDEX pgweb_idx_1 ON tsearch.pgweb USING gin(to_tsvector('english', body));
CREATE INDEX
omm=#
4.清理数据
omm=# drop schema tsearch;
DROP SCHEMA
omm=#