Import data from mysql to postgresql

Question

I have 2 models in my ruby app (jurnal and jurnal_my) and i need to import data jurnal from mysql to postgresql.

This is my method :

jurnal_my.rb

  establish_connection "mysql"
  self.table_name = "jurnal"

  def self.import_from_mysql
    JurnalMy.all.each{|jurnal|
      hash = {}
      JurnalMy.first.attributes.delete_if{|attr|%w(ID CREATED_AT UPDATED_AT).include?(attr)}.map{|case_attr|case_attr}.each{|hash_attr|
        hash = hash.merge(hash_attr[0].downcase => hash_attr[1])
      }
        Jurnal.create hash
    }
  end

database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  username: adit
  password: xxxxxxx
  pool: 5

development:
  <<: *default
  database: portalpos_development

mysql:
  adapter: mysql2
  encoding: utf8
  username: root
  password: xxxxxxx
  database: app

test:
  <<: *default
  database: portalpos_test

When i try to import data to postgresql, it's working. But the result is wrong. Data jurnal in mysql :

J01
J02
J03

Data jurnal in postgresql (result) :

J01
J01
J01

Can you help me?

Mario Pérez Alarcón · Accepted Answer · 2015-10-21 10:49:17Z

1

You're calling JurnalMy.first, hence you're only creating the first record. You should call attributes on jurnal. Also better to use find_each instead of loading all the records on memory.

JurnalMy.find_each do |jurnal|
  hash = {}
  jurnal.attributes # ...
  Jurnal.create hash
end

answered Oct 21, 2015 at 10:49

Mario Pérez Alarcón

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2 Comments

Sakti Over a year ago

I have try your method. Its work. But if I have 5 datum and import for twice. How to protect the postgres from duplicate data?

Mario Pérez Alarcón Over a year ago

Maybe you could use first_or_create for this. It'll be Jurnal.where(hash).first_or_create

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