Table replication in PostgreSQL

PostgreSQL Two methods are provided for table replication ：
1、create table as
2、create table like

Data preparation

Create a sequence 、 Primary key 、 notes 、CHECK Constrained tmp The table is used for subsequent tests ：

create table tmp(
 id SERIAL,
 name VARCHAR(100) primary key,
 num int CHECK(10<num and num<100)
);
comment on column tmp.id is ' Identification code ';
comment on column tmp.name is ' name ';
comment on column tmp.num is ' Number ';

insert into tmp(name,num) VALUES(' Apple ',61);
insert into tmp(name,num) VALUES(' Banana ',51);

Tabular DDL Exhibition ：

Let's talk about the results of the two table replication methods ：

create table as

Quite conventional method , When copying the table structure, you can also bring data . However, this copy will lose the comments of the original table 、 Constraints and other information .

create table tmp_x as select * from tmp where name=' Apple ';

DDL：

create table like

grammar ：create table tar_table LIKE source_table [ like_option ... ]
like_option There are several options ：
1、INCLUDING COMMENTS： notes
2、INCLUDING CONSTRAINTS ：CHECK constraint
3、INCLUDING DEFAULTS： The default expression defined by the copied column will be copied . The default behavior is to exclude the default expression , The default value of the copied column in the new table is null . Be careful , If the default value of the copy calls the database modification function （ Such as nextval）, It is possible to create a functional connection between the original table and the new table .
4、INCLUDING IDENTITY: Copy the identification statement defined by the copy field . Create a new sequence for each identity column of the new table , The sequence related to the old table is distinguished .
5、INCLUDING INDEXES ： Primary key constraint And index constraints
6、INCLUDING STORAGE： The copied column defines STORAGE Settings will be copied . The default behavior excludes STORAGE Set up , This causes the copied columns in the new table to have type related default settings
7、INCLUDING STATISTICS： The extended statistics will be copied to the new table
8、INCLUDING ALL： yes INCLUDING COMMENTS INCLUDING CONSTRAINTS INCLUDING DEFAULTS INCLUDING IDENTITY INCLUDING INDEXES INCLUDING STATISTICS INCLUDING STORAGE. Short form of .

Generally, we only use INCLUDING COMMENTS INCLUDING CONSTRAINTS INCLUDING INDEXES That's enough .

Example 1：

create table tmp_a (like tmp); 

Example 2：
Use only INCLUDING DEFAULTS Copy column definitions

create table tmp_b (like tmp INCLUDING defaults);

Example 3：
Use INCLUDING COMMENTS INCLUDING CONSTRAINTS INCLUDING INDEXES Copy notes 、 constraint

create table tmp_c (like tmp INCLUDING comments including constraints including indexes);

Of various copy results DDL：

Example 1

Example 2

Example 3

PostgreSQL 11.2 manual

The spring tide is even with the sea , The moon and the tide rise in the sea . -- Zhang Ruoxu 《 The spring river and the moon 》