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=#