Arquivo da categoria: PostgreSQL

gem pg not installing

 sudo sh -c "echo 'deb xenial-pgdg main' > /etc/apt/sources.list.d/pgdg.list"
 wget --quiet -O - | sudo apt-key add -
 sudo apt-get update
 sudo apt-get install postgresql-common
 sudo apt-get install postgresql-9.5 libpq-dev

How do you use variables in a simple PostgreSQL script?

DO $$
   a INTEGER := 10;  
   b INTEGER := 20;  
   c INTEGER;  
   c := a + b;
    RAISE NOTICE'Value of c: %', c;
END $$;

Peer authentication failed for user “postgres”, when trying to get pgsql working with rails

The problem is still your pg_hba.conf file (/etc/postgresql/9.1/main/pg_hba.conf). This line:
[code type=txt]local all postgres peer

Should be
[code type=txt]local all postgres md5

After altering this file, don’t forget to restart your PostgreSQL server. If you’re on Linux, that would be sudo service postgresql restart.

These are brief descriptions of both options according to the official PostgreSQL docs on authentication methods.

Peer authentication

The peer authentication method works by obtaining the client’s operating system user name from the kernel and using it as the allowed database user name (with optional user name mapping). This method is only supported on local connections.

Password authentication

The password-based authentication methods are md5 and password. These methods operate similarly except for the way that the password is sent across the connection, namely MD5-hashed and clear-text respectively.

If you are at all concerned about password “sniffing” attacks then md5 is preferred. Plain password should always be avoided if possible. However, md5 cannot be used with the db_user_namespace feature. If the connection is protected by SSL encryption then password can be used safely (though SSL certificate authentication might be a better choice if one is depending on using SSL).