I have devise gem in my application. I've been playing around with making some tables etc. Now I want to separate the database for the admin and the database for the user. I know its one single database. But, I'm not sure how to get it going in Rails.
you can configure multiple databases in database.yml file
production:
primary:
database: my_primary_database
user: root
adapter: mysql
secondary:
database: my_secondary_database
user: secondary_root
adapter: mysql
migrations_paths: db/secondary_migrate
and then in your modal, you can mention which database to use
class AnimalsBase < ApplicationRecord
self.abstract_class = true
connects_to database: { writing: :secondary }
end
checkout this link for more detail https://edgeguides.rubyonrails.org/active_record_multiple_databases.html
**For rails 4.2 - 5 ** you can use this gem Multiverse
P.S: Rails 6 is coming with a more neat solution for this, a stable build for rails 6 is now available you can upgrade to newer version too.
Rails have some limitation in which connecting only single database is major one. So I used to switch database using configuration setup in database.yml where you will have development & admin_development, (test & production etc. also)
You can get following constants,
ADMINCONFIG = YAML.load_file("#{Rails.root}/config/database.yml")['admin_development']
DEVCONFIG = YAML.load_file("#{Rails.root}/config/database.yml")['development']
And later whenever you need, you can switch from one to another as per requirement (through controller),
ActiveRecord::Base.connection(ADMINCONFIG)
Getting this error:
PG::InsufficientPrivilege: ERROR: permission denied to set parameter
"client_min_messages" to "warning" : SET client_min_messages TO
'warning' when connecting with redshift database.
enter image description here
My database.yml file setting looks like this
development:
adapter: postgresql
encoding: utf8
host: nacfhrcluster123.ctvpledrvuobs5.us-east-1.redshift.amazonaws.com
port: 5439
username: nacfhr123
password: NACFDChr12345!
database: devnacfhrdc
pool: 5
schema_search_path: 'beta'
timeout: 5000
min_messages: warning
Thank you guys for your responses. I resolved the issue by adding a gem with the name 'activerecord5-redshift-adapter' in my gemfile. So you have to add below line in your gem file.
gem 'activerecord5-redshift-adapter'
And then run bundle install again.
It is important to realise that Redshift IS NOT Postgres. There are many differences.
One difference is that the available parameters are much different, the only parameters that can be set on Redshift are:
analyze_threshold_percent
datestyle
extra_float_digits
query_group
search_path
statement_timeout
wlm_query_slot_count
You will need to alter your rails connection so that is does not request this parameter to be set.
I guess that means removing min_messages: warning
I hope this will help. As far as I know there is no active records available for Redshift and it don't it make sense as well as Redshift is not a typical RDBMS.
We have similar scenario where we use ROR for front end for one of analytics and planing application.
Here is our app scenario:
Front-end : ROR
Database : mysql(OLTP)
Datawarehouse : Redshift(OLAP)
This is how data flows back and forth between ROR and Redshift.
Insert/updates from ROR to Redshift(happens very rarely).
For any operations from ROR that impacts something on data warehouse, ROR executes PSQL commands with specific query, not via active records.
SELECT from Redshift(happens frequently)
Similarly, for getting data from DW for various reason done via select query and redirection to file using PSQL command, then it import it into OLTP using myssqlimport.
Link for psql, mysqlimport tools that we use.
Comment if you have further specific followup questions.
I have just started to use the octopus gem with rails, i tried like for the normal case
octopus:
replicated: true
fully_replicated: false
environments:
- development
development:
shard_one:
host: localhost
adapter: postgresql
database: app_development
the above i have used for the testing purpose also the main thing is used as the controller specific, not the model specific. I put this in application controller
def select_shard(&block)
Octopus.using(:shard_two, &block)
end
and call that method in appropriate controller, so its works, but when i move to heroku i have followed this https://devcenter.heroku.com/articles/distributing-reads-to-followers-with-octopus, because i need the reads only for some controller. so in this case how can i use that follower on controller specific?
I'm trying to add test fixtures to a rails (v 3.1.3) app that uses multiple databases.
The fixture should be applied only to the applications own test sqlite database:
test:
adapter: sqlite3
database: db/test.sqlite3
pool: 5
timeout: 5000
The 2 other databases are mysql and also have test instances called %dbname%_test and are already filled with test data.
After I added the fixtures all my test fail with "ActiveRecord::StatementInvalid: Mysql::Error: Unknown column" errors as rails is trying to apply the fixture to
one of the mysql databases.
Is there a way to specify which database a fixture is made for?
Fixtures-init code (in activerecord-3.2.6/lib/active_record/fixtures.rb) has a bug: in the "initialize" method, in the "else" on line 544, #connection needs to be initialized to #model_class.connection. (Without that, #connection is simply "connection" which points to the wrong DB.)
In database.yml, add a connection for each of the other databases for each environment:
other_one_test:
adapter: mysql
# ...
other_two_test:
# ...
other_one_development:
# ...
other_two_development:
# ...
In your models that use the other databases, connect to them using
establish_connection("other_one_test")
You'll probably want to create a Base class model for each different database connection and use that for all models connecting to that database:
class OtherOneBase < ActiveRecord::Base
establish_connection "other_one_#{Rails.env}"
end
class SomeModel < OtherOneBase
end
If you set up your models correctly, your fixtures will use the correct database.
Can this be done? In a single application, that manages many projects with SQLite.
What I want is to have a different database for each project my app is managing.. so multiple copies of an identically structured database, but with different data in them. I'll be choosing which copy to use base on params on the URI.
This is done for 1. security.. I'm a newbe in this kind of programming and I don't want it to happen that for some reason while working on a Project another one gets corrupted.. 2. easy backup and archive of old projects
Rails by default is not designed for a multi-database architecture and, in most cases, it doesn't make sense at all.
But yes, you can use different databases and connections.
Here's some references:
ActiveRecord: Connection to multiple databases in different models
Multiple Database Connections in Ruby on Rails
Magic Multi-Connections
If you are able to control and configure each Rails instance, and you can afford wasting resources because of them being on standby, save yourself some trouble and just change the database.yml to modify the database connection used on every instance. If you are concerned about performance this approach won't cut it.
For models bound to a single unique table on only one database you can call establish_connection inside the model:
establish_connection "database_name_#{RAILS_ENV}"
As described here: http://apidock.com/rails/ActiveRecord/Base/establish_connection/class
You will have some models using tables from one database and other different models using tables from other databases.
If you have identical tables, common on different databases, and shared by a single model, ActiveRecord won't help you. Back in 2009 I required this on a project I was working on, using Rails 2.3.8. I had a database for each customer, and I named the databases with their IDs. So I created a method to change the connection inside ApplicationController:
def change_database database_id = params[:company_id]
return if database_id.blank?
configuration = ActiveRecord::Base.connection.instance_eval { #config }.clone
configuration[:database] = "database_name_#{database_id}_#{RAILS_ENV}"
MultipleDatabaseModel.establish_connection configuration
end
And added that method as a before_filter to all controllers:
before_filter :change_database
So for each action of each controller, when params[:company_id] is defined and set, it will change the database to the correct one.
To handle migrations I extended ActiveRecord::Migration, with a method that looks for all the customers and iterates a block with each ID:
class ActiveRecord::Migration
def self.using_databases *args
configuration = ActiveRecord::Base.connection.instance_eval { #config }
former_database = configuration[:database]
companies = args.blank? ? Company.all : Company.find(args)
companies.each do |company|
configuration[:database] = "database_name_#{company[:id]}_#{RAILS_ENV}"
ActiveRecord::Base.establish_connection configuration
yield self
end
configuration[:database] = former_database
ActiveRecord::Base.establish_connection configuration
end
end
Note that by doing this, it would be impossible for you to make queries within the same action from two different databases. You can call change_database again but it will get nasty when you try using methods that execute queries, from the objects no longer linked to the correct database. Also, it is obvious you won't be able to join tables that belong to different databases.
To handle this properly, ActiveRecord should be considerably extended. There should be a plugin by now to help you with this issue. A quick research gave me this one:
DB-Charmer: http://kovyrin.github.com/db-charmer/
I'm willing to try it. Let me know what works for you.
I got past this by adding this to the top of my models using the other database
class Customer < ActiveRecord::Base
ENV["RAILS_ENV"] == "development" ? host = 'devhost' : host = 'prodhost'
self.establish_connection(
:adapter => "mysql",
:host => "localhost",
:username => "myuser",
:password => "mypass",
:database => "somedatabase"
)
You should also check out this project called DB Charmer:
http://kovyrin.net/2009/11/03/db-charmer-activerecord-connection-magic-plugin/
DbCharmer is a simple yet powerful plugin for ActiveRecord that does a few things:
Allows you to easily manage AR models’ connections (switch_connection_to method)
Allows you to switch AR models’ default connections to a separate servers/databases
Allows you to easily choose where your query should go (on_* methods family)
Allows you to automatically send read queries to your slaves while masters would handle all the updates.
Adds multiple databases migrations to ActiveRecord
It's worth noting, in all these solutions you need to remember to close custom database connections. You will run out of connections and see weird request timeout issues otherwise.
An easy solution is to clear_active_connections! in an after_filter in your controller.
after_filter :close_custom_db_connection
def close_custom_db_connection
MyModelWithACustomDBConnection.clear_active_connections!
end
in your config/database.yml do something like this
default: &default
adapter: postgresql
encoding: unicode
pool: 5
development:
<<: *default
database: mysite_development
test:
<<: *default
database: mysite_test
production:
<<: *default
host: 10.0.1.55
database: mysite_production
username: postgres_user
password: <%= ENV['DATABASE_PASSWORD'] %>
db2_development:
<<: *default
database: db2_development
db2_test:
<<: *default
database: db2_test
db2_production:
<<: *default
host: 10.0.1.55
database: db2_production
username: postgres_user
password: <%= ENV['DATABASE_PASSWORD'] %>
then in your models you can reference db2 with
class Customers < ActiveRecord::Base
establish_connection "db2_#{Rails.env}".to_sym
end
What you've described in the question is multitenancy (identically structured databases with different data in each). The Apartment gem is great for this.
For the general question of multiple databases in Rails: ActiveRecord supports multiple databases, but Rails doesn’t provide a way to manage them. I recently created the Multiverse gem to address this.
The best solution I have found so far is this:
There are 3 database architectures that we can approach.
Single Database for Single Tenant
Separate Schema for Each Tenant
Shared Schema for Tenants
Note: they have certain pros and cons depends on your use case.
I got this from this Blog! Stands very helpful for me.
You can use the gem Apartment for rails
Video reference you may follow at Gorails for apartment
As of Rails 6, multiple databases are supported: https://guides.rubyonrails.org/active_record_multiple_databases.html#generators-and-migrations
Sorry for the late and obvious answer, but figured it's viable since it's supported now.