结果如下： 结论： 1.LOCATE，INSTR，REGEXP三个函数，效果在like面前没有任何优势。
在PostgreSQL中,LIKE 运算符通常用于搜索列中的特定模式,但它并不直接支持多个值的匹配。如果你需要匹配多个值或模式,有几种方法可以实现这一点。 方法一:使用 OR 连接多个 LIKE 条件 这是最直接的方法,通过 OR 将多个 LIKE 条件连接起来。例如,如果你想在一个名为 employees 的表中查找名字以 "A" 或 "B"...
EXPLAIN ANALYZE select * from gallery_map where author like '曹志耘'; QUERY PLAN --- Bitmap Heap Scan on gallery_map (cost=36.36..2715.37 rows=1025 width=621) (actual time=0.752..2.119 rows=1031 loops=1) Filter: ((author)::text ~~ '曹志耘'::text) Heap Blocks: exact=438 -> Bitma...
1 row in set (0.03 sec) (twDB)root@localhost [sysbench]> 结论 在PostgreSQL中,千万别对int类型进行like会无法使用索引的
问PostgreSQL: Where子句使用LIKE、ANY和通配符EN数据库优化: 1.可以在单个SQL语句，整个应用程序，单个...
Query: DDL select id, firstname, lastname from usertable where firstname = ‘foo’; Index would not be used in this case as lastname is not part of indexed or covered column. This can be verified by looking at the explain plan. To fix this create index that has either lastname part...
wuxqing9年前 一、未做索引的查询效率 作为对比,先对未索引的查询做测试 EXPLAIN ANALYZE select * from gallery_map where author = '曹志耘'; QUERY PLAN --- Seq Scan on gallery_map (cost=0.00..7002.32 rows=1025 width=621) (actual time=0.011..39.753 rows=1031 loops=1) Filter: ((author):...
Summary: in this tutorial, you will learn how to use the PostgreSQL LIKE operators to query data based on patterns. Introduction to PostgreSQL LIKE operator Suppose that you want to find customers, but you don’t remember their names exactly. However, you can recall that their names begin wit...
sqlalchemy查询使用1.带条件查询查询是最常用的,对于各种查询我们必须要十分清楚,首先是带条件的查询#带条件查询 rows = session.query(User).filter_by(username='jingqi').all() print(rows) rows1 = session.query(User).filter(User.username=='jingqi') SQLAlchemy sql查询 User sqlalchemy 关联对象 转...
随着pg越来越强大,abase目前已经升级到5.0(postgresql10.4),目前abase5.0继承了全文检索插件(zhparser),使用全文检索越来越方便。本文会对abase支持的like模糊匹配,全文检索,创建何种索引,如何使用进行说明。针对于各种模糊匹配均可走索引 前模糊匹配(%xxx),后模糊匹配(xxx%) ...