Postgres and Open Source Experts

To install PostgreSQL on CentOS, execute the “sudo yum install postgresql-server postgresql-contrib” script.

In PostgreSQL, CARDINALITY() is an array function that counts the total number of array elements. The return type of the stated function is INT.

In PostgreSQL, the “pg_ctl” command and “services manager” can be used to restart the Postgres server on the Windows operating system.

To lock a Postgres user, the “ALTER USER” statement can be used with the “NOLOGIN” clause. While a user can be unlocked by using the “ALTER USER” command with the “LOGIN” attribute.

In Postgres, to check the active users via the “pg_stat_activity”, use the “SELECT usename, datname, state FROM pg_stat_activity WHERE usename='user_name';” command.

In PostgreSQL, the GRANT statement is utilized along with the “ON ALL TABLES” clause to assign permissions on all tables to single or multiple users.

To change or modify the table’s owner in PostgreSQL, use the “ALTER TABLE tab_name OWNER TO new_owner_name;” command.

In PostgreSQL, the “GRANT ALL” statement is utilized along with the “ON ALL TABLES IN SCHEMA” clause to assign permissions on the schema to single or multiple users.

In PostgreSQL, the “\z” command and “information_schema” can be used to check the list of assigned privileges to a certain Postgres table.

In PostgreSQL, the “\d”, the “\d+”, “information_schema”, and the “SELECT *” statement with the “FALSE” option are used to check the table’s structure.