如果我不为数据库定义特定模式会怎样？

Question

如果数据库中未定义特定模式，数据库对象将存储在哪里？这是好事还是坏事？为什么？

Answer 1

In the previous sections we created tables without specifying any schema names. By default such tables (and other objects) are automatically put into a schema named “public”. Every new database contains such a schema

如果在创建 table 时未定义架构，schema search path 中找到的第一个（现有）架构将用于存储 table。

Answer 2

在psql

create database sch_test;
CREATE DATABASE

\c sch_test 
You are now connected to database "sch_test" as user "postgres".

--Show available schemas
\dn
  List of schemas
  Name  |  Owner   
--------+----------
 public | postgres

drop schema public ;
DROP SCHEMA

\dn
List of schemas
 Name | Owner 
------+-------
(0 rows)

show search_path ;
   search_path   
-----------------
 "$user", public

create table tbl(id integer);
ERROR:  no schema has been selected to create in
LINE 1: create table tbl(id integer);

create table test.tbl(id integer);
ERROR:  schema "test" does not exist
LINE 1: create table test.tbl(id integer);

只是为了说明如果模式不存在，则可能不会创建对象。底线是需要在模式中创建的对象（table、函数等）。如果有 none 可供 search_path 查找，或者您专门指向一个不存在的对象，则对象创建将失败。

如果我不为数据库定义特定模式会怎样？

What happens if I don´t define a specific schema to the database?

sql

postgresql

schema