The following query shows that PostgreSQL scans the GIN index when using the ILIKE operator: postgres=>EXPLAINANALYZESELECT*FROMpublic.case_test_opt1WHEREemailILIKE'FOO.BAR500@EXAMPLE%';QUERYPLAN---Bitmap Heap Scanoncase_test_opt1(cost=344.77..709.64rows=99width=37)(actualtime=84.869..86.652row...
There are three known solutions to case-insensitive search in PostgreSQL: Explicit conversion with lower() or upper() A query that uses this method would look as follows: 1 2 SELECT id, col FROM tab WHERE lower(col) = lower('search string'); This can be made fast with a B-tree ind...
Summary: in this tutorial, you will learn how to use the PostgreSQL CASE conditional expression to form conditional queries. The PostgreSQL CASE expression is the same as IF/ELSE statement in other programming languages. It allows you to add if-else logic to the query to form a powerful query...
PostgreSQL是一种开源的关系型数据库管理系统,它支持广泛的数据类型和功能,被广泛用于各种应用场景。在PostgreSQL中,可以使用case语句在select查询中对列进行条件判断和转换。 case语句是一种条件表达式,它允许根据条件的不同返回不同的值。在select查询中,可以使用case语句对列进行条件判断,并根据条件返回不同的值或执行...
importpsycopg2importpandasaspdfromsqlalchemyimportcreate_engine,text# 连接数据库取数engine=create_engine('postgresql+psycopg2://postgres:123456@127.0.0.1:5432/sql_advanced')df=pd.read_sql_query('SELECT * FROM poptbl',engine)# 创建一个字典,用来映射pref_name和districtdistrict_map={'德岛':'九州',...
PostgreSQL查询case 的相关内容阿里云文档 2024-11-08 如何使用Query Cache查询缓存 AnalyticDB PostgreSQL 7.0版支持Query Cache(查询缓存)。该版本的Query Cache在AnalyticDB PostgreSQL 6.0版的基础上进行了部分重构,能够支持更大规模的单次查询的缓存和整个实例的缓存集大小。
在PostgreSQL中有一个函数可以直接得出结果: selectkey_name,GREATEST(x,y,z)ASmaximum_valueFROMgreatests; 那么如果不使用自带的函数方法,该怎么是现在这个需求呢?我们使用两两比较的方式进行判断,我们可以写出这样的语句: selectkey_name,CASEWHENx>=yANDx>=zTHENxWHENy>=xANDy>=zTHENyelsezENDASgreatestFROMgreates...
Under such circumstances, there comes the need forcase-insensitivequeries. The case-insensitive queries will return the search results without bothering about the case. Let’s see how can we query the case-insensitive queries in PostgreSQL.
PostgreSQL中,有多种方法支持这种场景: 《PostgreSQL 9种索引的原理和应用场景》 1、方法1,每个字段加一个索引(普通类型用btree, 多值类型(数组,json,全文检索,枚举等类型)用gin, 空间、范围类型用gist,时序类型用brin)。 2、方法2,使用单个复合索引,把所有字段放到GIN倒排索引接口中。
When you insert some records, notice that PostgreSQL will accept “duplicated terms”. INSERTINTOusers(name,username)VALUES('John Doe','john');INSERTINTOusers(name,username)VALUES('Doe, John','JOHN'); If you select all records with a query likeSELECT * FROM usersyou can see that you have...