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PostgreSQL Privileges Assigning

  • When an object is created, it is assigned an owner. The owner is normally the role that executed the creation statement. 
  • For most kinds of objects, the initial state is that only the owner (or a superuser) can do anything with the object. To allow other roles to use it, privileges must be granted. 
  • There are several different kinds of privilege: SELECT, INSERT, UPDATE, DELETE,REFERENCES, TRIGGER, CREATE, CONNECT, TEMPORARY, EXECUTE, and USAGE.
Privileges:
  • SELECT - Ability to perform SELECT statements on the table.
  • INSERT - Ability to perform INSERT statements on the table.
  • UPDATE - Ability to perform UPDATE statements on the table.
  • DELETE - Ability to perform DELETE statements on the table.
  • TRUNCATE - Ability to perform TRUNCATE statements on the table.
  • REFERENCES - Ability to create foreign keys (requires privileges on both parent and child tables).
  • TRIGGER - Ability to create triggers on the table.
  • CREATE - Ability to perform CREATE TABLE statements.
  • ALL - Grants all permissions.
  • EXECUTE - Grant file Execute permission
PRIVILEGES To:
----------
1) GROUPS
2) USERS
3) ROLES
4) SCHEMA & SEARCH PATH
  • Lab to create USERS, SCHEMAS, ROLES, Alter SEARCH_PATH,
  • GRANT and REVOKE privileges
5) OBJECT OWNERSHIP

1)GROUPS:
A group to whom to grant privileges
granting privileges is from enterprisedb
grant all privileges on database <db_name> to <group_name>
2.USERS:
when the uer create a table, those table belong to the PUBLIC schema Database can be split up between multiple users usign schemas.

granting privileges is from enterprisedb
grant all privileges on database <db_name> to <user_name>
grant all privileges on <table_name> to <user_name>
Revoking privileges is from enterprisedb
revoke all privileges on database <db_name> from <user_name>
Grant insert privilege to all users on table tab1:
GRANT INSERT ON tab1 TO PUBLIC;
Grant all available privileges to user manuel on view kinds:
GRANT ALL PRIVILEGES ON emp TO nijam;
Note that while the above will indeed grant all privileges if executed by a superuser or the owner of "emp", when executed by someone else it will only grant those permissions for which the someone else has grant options.

Grant membership in role admins to user nijam:
GRANT admins TO nijam;
3.ROLE:
Database roles are conceptually completely separate from operating system users. In practice it might be convenient to maintain a correspondence, but this is not required. Database roles are global across a database cluster installation (and not per individual database)
To assign privileges, the GRANT command is used. So, if "nijam" is an existing role, and "emp" is an existing table, the privilege to update the table can be granted with
GRANT UPDATE ON emp TO nijam;
The special name PUBLIC can be used to grant a privilege to every role on the system. Writing ALL in place of a specific privilege specifies that all privileges that apply to the object will be granted.
GRANT all ON emp TO public;
4.SCHEMA:
Each user have their own schema and multiple schema the schema search path can be altered so that each user find their tables first and access the other user tables also.schema as a namespace for tables that also provides security.By creating a schema for users and granting them rights on that schema,The user will create tables on that schema instead of public.schema search path is set which users objects  set in postgreSQL database.
 default for all users $user, public.
  search path can be set on a users basis, to look thorough any random list of schemas.
Use psql's \dp command to obtain information about existing privileges for tables and columns
=> \dp emp
Access privileges
Schema |  Name   | Type  |   Access privileges   | Column access privileges 
--------+---------+-------+-----------------------+--------------------------
 public | emp     | table | u1=arwdDxt/u1 | col1:
: =r/u1             :       u1_rw=rw/u1
: admin=arw/u1        
(1 row)

The entries shown by \dp are interpreted thus:
rolename=xxxx -- privileges granted to a role
     xxxx -- privileges granted to PUBLIC
            r -- SELECT ("read")
            w -- UPDATE ("write")
            a -- INSERT ("append")
            d -- DELETE
            D -- TRUNCATE
            x -- REFERENCES
            t -- TRIGGER
            X -- EXECUTE
            U -- USAGE
            C -- CREATE
            c -- CONNECT
            T -- TEMPORARY
      arwdDxt -- ALL PRIVILEGES (for tables, varies for other objects)
            * -- grant option for preceding privilege
        /yyyy -- role that granted this privilege   =

5.OBJECT OWNERSHIP:
We gave  connect privilege to user for database connect
GRANT CONNECT ON DATABASE database_name TO user_name;
We gave  connect privilege to ALL user for database connect
GRANT CONNECT ON DATABASE database_name TO Public;
GRANT CONNECT ON DATABASE database_name TO user_name;
REVOKE ALL ON ALL TABLES IN SCHEMA schema_name FROM PUBLIC;
GRANT CONNECT ON DATABASE database_name TO user_name;

we gave permission to access all objects in database on particular user
grant all privileges on database dbname to dbuser;
GRANT CONNECT ON DATABASE database_name TO user_name;
Create role with Login privilege
CREATE ROLE demo_role WITH LOGIN;
GRANT CONNECT ON DATABASE database_name TO user_name;
Revoke  Login Permission
ALTER ROLE demo_role WITH NOLOGIN;
GRANT CONNECT ON DATABASE database_name TO user_name;
GRANT UPDATE ON demo TO demo_role;
GRANT INSERT ON demo TO PUBLIC;
To view the grant table
\z
                                    Access privileges
 Schema |    Name     |   Type   |     Access privileges      | Column access privileges
--------+-------------+----------+----------------------------+------------------------  
 public | demo        | table    | postgres=arwdDxt/postgres +|
        |             |          | demo_role=w/postgres      +|
        |             |          | test_user=arwdDxt/postgres+|
        |             |          | =a/postgres                |
 public | demo_id_seq | sequence |                            |
(2 rows)
CREATE ROLE temporary_users;
GRANT temporary_users TO demo_role;
GRANT temporary_users TO test_user;                                           

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