psql: FATAL: Peer authentication failed for user “expman”

Question

I'm trying to restore a database from backup but I can't connect to postgresql.

namespace :db do
  task import: :environment do
  import_path = "~/backups"
  sql_file = "PostgreSQL.sql"
  database_config = Rails.configuration.database_configuration[Rails.env]

  system "psql --username=#{database_config['username']} -no-password # {database_config['database']} < #{import_path}/#{sql_file}"
  end
end

I tried changing the pg_hba.conf file (peer to md5). In the console I tried the same thing with the super user postgres, but it still fails.

BTW, does anyone know a better way to restore a database? I used the backup gem.

EDIT: I restarted the postgresql server and the passed the authentication. But, didn't restored the db. I reverted the changes in the file and just added -h localhost to the psql command. The database restores now. The only errors I get now are:

must be owner of extension plpgsql //and
no privileges could be revoked for "public"

Answer 1

1. after change pg_hba.conf, you shold reload or send a SIGHUP signal to postmaster pid. so that change applyed.
2. why not use psql -f to execute the backup sql file?

3. or you can use pg_dump backup and pg_restore restore. or copy command backup and restore. LIKE :

   digoal=# copy tbl_join_1 to '/home/pg93/tbl_join_1.dmp';
   COPY 10
   digoal=# delete from tbl_join_1;
   DELETE 10
   digoal=# copy tbl_join_1 from '/home/pg93/tbl_join_1.dmp';
   COPY 10
   

   OR

   pg93@db-172-16-3-150-> pg_dump -f ./tbl_join_1.dmp -t tbl_join_1
   pg93@db-172-16-3-150-> psql
   psql (9.3.3)
   Type "help" for help.
   
   digoal=# drop table tbl_join_1;
   DROP TABLE
   digoal=# \q
   pg93@db-172-16-3-150-> psql -f ./tbl_join_1.dmp 
   SET
   SET
   SET
   SET
   SET
   SET
   SET
   SET
   SET
   CREATE TABLE
   ALTER TABLE
   ALTER TABLE