Обсуждение: why schema name is same as username behaves different then others

Note:
test=# super user postgres
test=> regular user robot
### comments


test=#create schema t AUTHORIZATION robot;
CREATE SCHEMA
test=> select * from pg_namespace ;
  nspname   | nspowner | nspacl
------------+----------+--------
 pg_catalog |        1 | {=U}
 pg_toast   |        1 | {=}
 public     |        1 | {=UC}
 pg_temp_1  |        1 |
 t          |     1045 |

test=> create table foo(test text);
CREATE TABLE
test=> \dt
       List of relations
 Schema | Name | Type  | Owner
--------+------+-------+-------
 public | foo  | table | robot
test=> create table t.foo(test text);
CREATE TABLE
test=> \dt
       List of relations
 Schema | Name | Type  | Owner
--------+------+-------+-------
 public | foo  | table | robot
(1 row)
####I expect to see something like:
       List of relations
 Schema | Name | Type  | Owner
--------+------+-------+-------
 public | foo  | table | robot
 t      | foo  | table | robot

test=> insert into foo values('zzzz');
INSERT 19868125 1
test=> insert into t.foo values('sssss');
INSERT 19868126 1
test=> select * from foo;
 test
------
 zzzz
(1 row)


test=# create schema robot AUTHORIZATION robot;
CREATE SCHEMA
test=> select * from pg_namespace ;
  nspname   | nspowner | nspacl
------------+----------+--------
 pg_catalog |        1 | {=U}
 pg_toast   |        1 | {=}
 public     |        1 | {=UC}
 pg_temp_1  |        1 |
 t          |     1045 |
 robot      |     1045 |
(6 rows)

test=> create table robot.foo(test text);
CREATE TABLE
test=> \dt
       List of relations
 Schema | Name | Type  | Owner
--------+------+-------+-------
 robot  | foo  | table | robot
(1 row)

####I expect to see something like:
       List of relations
 Schema | Name | Type  | Owner
--------+------+-------+-------
 public | foo  | table | robot
 t      | foo  | table | robot
 robot  | foo  | table | robot
#### why it's not?
test=> insert into robot.foo values('xxxxx');
INSERT 19868173 1
test=> select * from foo;
 test
-------
 xxxxx
(1 row)
#### why schema t,robot behave different???
#### it seems if schema name is same as username then
#### it will shadow the objects in the public schema that have same name.
#### I haven't documentation address this yet.

Jie Liang
Software Engineer
St. Bernard Software
16882 W. Bernardo Dr.
San Diego, CA 92127
Tel: 858-524-2134
Fax:858-676-2228
jie@stbernard.com

Jie Liang <jie@stbernard.com> writes:
> ####I expect to see something like:

You're neglecting the effects of search path.  \dt only shows what's
visible in your search path.  (IIRC, \dt *.* is the easiest way to
see all tables regardless of search path.)

> #### it seems if schema name is same as username then
> #### it will shadow the objects in the public schema that have same name.

That's what it's supposed to do, and yes this is documented, and yes
you can change it if you don't like it.  Read about search_path.

            regards, tom lane

Jie Liang wrote:
> ####I expect to see something like:
>        List of relations
>  Schema | Name | Type  | Owner
> --------+------+-------+-------
>  public | foo  | table | robot
>  t      | foo  | table | robot

That's because schema t is not in your search path. By default,
search path is:

regression=# show search_path ;
  search_path
--------------
  $user,public
(1 row)

So you are not seeing the table in schema foo. If you do:
regression=# create user robot;
CREATE USER
regression=# create schema t AUTHORIZATION robot;
CREATE SCHEMA
regression=# drop table foo;
DROP TABLE
regression=# create table foo(test text);
CREATE TABLE
regression=# create table t.foo(test text);
CREATE TABLE
regression=# \dt
          List of relations
  Schema |  Name  | Type  |  Owner
--------+--------+-------+----------
  public | foo    | table | postgres
  public | table1 | table | postgres
  public | table2 | table | postgres
(3 rows)

regression=# set search_path to 't','public';
SET
regression=# \dt
          List of relations
  Schema |  Name  | Type  |  Owner
--------+--------+-------+----------
  public | table1 | table | postgres
  public | table2 | table | postgres
  t      | foo    | table | postgres
(3 rows)

The $user in the default search path allows user robot to automatically find
objects in schema robot first.

You can change the default search path for the installation in
postgresql.conf, or you can change in via ALTER DATABASE or ALTER USER to be
effective in just one database or for one user respectively.

HTH,

Joe