PostgreSQL - 从模板数据库创建数据库

Question

If I create a database foo that:

1. Has initial data
2. Loads custom stored procedures
3. Loads and uses an external library

If I create a database foobar like this:

CREATE DATABASE foobar WITH ENCODING 'UTF8' TEMPLATE foo;

Will database foobar have:

1. The same data that foo was initialised with
2. The same custom stored procedures loaded by foo
3. The ability to use the shared library loaded in foo

[[Addendum]]

I have written several C library extensions which are loaded as shared libraries in the database I am using as a template. My main concern is whether these libraries will be also loaded by subsequent databases based on the template.

Answer 1

You need to set the database foo as a template database.

ALTER DATABASE foo IS_TEMPLATE true ;

Then you can use it to create new databases

CREATE DATABASE foobar TEMPLATE foo;

Answer 2

why don't you try yourself?..

t=# create database foo;
CREATE DATABASE
Time: 426.799 ms
t=# \c foo
You are now connected to database "foo" as user "postgres".

data:

foo=# create table b(i int);
CREATE TABLE
Time: 3.794 ms
foo=# insert into b select 43;
INSERT 0 1
Time: 13.608 ms

fn():

foo=# create function a() returns int as $$select 42;$$ language sql;
CREATE FUNCTION
Time: 1.548 ms

extension:

foo=# create extension pg_stat_statements;
CREATE EXTENSION
Time: 4.275 ms

using template:

foo=# create database boo template foo;
CREATE DATABASE
Time: 640.328 ms
foo=# \c boo
You are now connected to database "boo" as user "postgres".

data is there:

boo=# select count(1) from b;
 count
-------
     1
(1 row)

Time: 1.569 ms

extension is usable:

boo=# select count(1) from pg_stat_statements;
 count
-------
  4927
(1 row)

Time: 1023.658 ms

fn() returns same result:

boo=# select a();
 a
----
 42
(1 row)

Time: 0.399 ms