Update 'PostgreSqlUbuntu'

PostgreSqlUbuntu.md

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+# Install PostgreSQL
+
+`sudo apt install postgresql postgresql-contrib`
+
+response:
+The following additional packages will be installed:\
+  libllvm10 postgresql-12 postgresql-client-12 postgresql-client-common postgresql-common ssl-cert sysstat\
+Suggested packages:\
+  postgresql-doc postgresql-doc-12 libjson-perl openssl-blacklist isag\
+The following NEW packages will be installed:\
+  libllvm10 postgresql postgresql-12 postgresql-client-12 postgresql-client-common postgresql-common\
+  postgresql-contrib ssl-cert sysstat\
+0 upgraded, 9 newly installed, 0 to remove and 10 not upgraded.
+
+After installing PostgreSQL, the commands below can be used to stop, start, enable and check its status:
+
+```bash
+sudo systemctl stop postgresql.service
+sudo systemctl start postgresql.service
+sudo systemctl enable postgresql.service
+sudo systemctl status postgresql.service
+```
+
+Viewing the server version\
+`/usr/lib/postgresql/12/bin/postgres -V`\
+response:\
+postgres (PostgreSQL) 12.2 (Ubuntu 12.2-4)
+
+## Create PostgreSQL Linux User Password
+
+After installing PostgreSQL, it’s a good idea to create / change the default PostgreSQL user password
+
+`sudo passwd postgres`
+
+You should be prompted to create a new Linux password for postgres user.
+
+```bash
+New password:
+Retype new password:
+passwd: password updated successfully
+```
+
+## CONNECTIONS AND AUTHENTICATION
+
+### postgresql.conf
+
+Most global configuration settings are stored in postgresql.conf, which is created automatically when you install PostgreSQL. Open this file in your preferred text editor:\
+`sudo nano /etc/postgresql/10/main/postgresql.conf`
+
+By default, Postgres only listens on localhost. However, by editing the listen_addresses-section and replacing localhost with an IP, you can force Postgres to listen on another IP. Use '*' to listen on all IP addresses, restrict access via firewall.\
+`listen_addresses= '*'`
+
+### pg_hba.conf
+
+It’s now time to open the (in)famous pg_hba.conf configuration file, located at /etc/postgresql/10/main/pg_hba.conf:
+
+`sudo nano /etc/postgresql/10/main/pg_hba.conf`
+
+HBA stands for host-based authentication. Basically, this file is used to control how PostgreSQL users are authenticated.\
+`host all all 127.0.0.1/32 md5`\
+This line allows "all" users to login using TCP/IP ("host") from the localhost "127.0.0.1/32" to "all" databases, if they succeed in password authentication using the "md5" method. There are more password authentication methods (md5, scram-sha-256, gss, ldap, …) than we can cover, so let’s just get back to simpler examples.
+
+In most cases the access is restricted to localhost and the clients vlan e.g.:
+
+```ini
+# existing entry, allows connections from localhost
+host    all     all    127.0.0.1/32        md5
+
+# new entry to allow connections from 192.168.101.1/24 subnet,
+host    all     all    192.168.101.1/24    md5
+
+# ip of your webserver
+host    all     all   xxx.xxx.xxx.xxx/32    md5
+```
+
+## App database setup
+
+let’s connect as the superuser “postgres” to make the changes:\
+`sudo su -l postgres`
+
+Then use the psql command in an interactive shell when you want to create and manage PostgreSQL databases:\
+`psql`
+
+On psql shell, run below command to change database admin password:\
+`alter user postgres password 'new_db_admin_password';`
+
+Create a admin user called tethys_admin with new password:\
+`postgres=# create user tethys_admin with encrypted password 'new_password_here';`
+
+Create an app user called tethys_app with new password:\
+`postgres=# create user tethys_app with encrypted password 'new_password_here';`
+
+then create a database called tethys via psql:\
+`postgres=# create database tethys;`\
+use postgres ist default owner of db tethys
+
+exit psql:\
+`\q`
+
+and re-login into tethys db:\
+`psql -d tethys -U postgres -p 5432`
+
+create a schemma 'gba' for all tethys tabels with full authorization for the user 'tethys_admin':\
+`tethys=# CREATE SCHEMA IF NOT EXISTS gba AUTHORIZATION tethys_admin;`
+
+grant select, insert, update and delete privileges for the user 'tethys_app':\
+
+```sql
+grant usage on schema gba to tethys_app;
+
+grant select, insert, update, delete on all tables in schema gba to tethys_app;
+alter default privileges for role tethys_admin in schema gba grant select, insert, update, delete on tables to tethys_app;
+
+grant usage on all sequences in schema gba to tethys_app;
+alter default privileges for role tethys_admin in schema gba grant usage on sequences to tethys_app;
+
+grant execute on all functions in schema gba to tethys_app;
+alter default privileges for role tethys_admin in schema gba grant execute on functions to tethys_app;
+```
+
+exit psql:\
+`\q`
+
+switch back to your os user:\
+`exit`
+
+[go mack to main installation](https://github.com/geolba/tethys/wiki#step-4-download-and-install-tethys)