PgpoolNoLoadBalance

This gem exists for you to use Pgpool-II's load balancing feature.

If you don't want a query that qualifies for the load balancing to be load balanced by Pgpool-II, you can put arbitrary comment(/*NO LOAD BALANCE*/ is usually used) before the SELECT statement. This will disable the load balance of the particular query and Pgpool-II will send it to the master node (the primary node in Master Slave mode).

Add this line to your application's Gemfile:

gem 'pgpool_no_load_balance'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install pgpool_no_load_balance

Using the pgpool_nlb method will add a comment to the SQL.

irb(main):001:0> User.pgpool_nlb.all
  /*NO LOAD BALANCE*/ SELECT "users".* FROM "users" LIMIT $1  [["LIMIT", 11]]

Can remove the scope with the unscope method.

irb(main):001:0> user_relation = User.where(name: 'elengine').pgpool_nlb

irb(main):002:0> user_relation.count
  /*NO LOAD BALANCE*/ SELECT COUNT(*) FROM "users" WHERE "users"."name" = $1  [["name", "elengine"]]

irb(main):003:0> user_relation.unscope(:pgpool_nlb).order(:id).limit(3)
  SELECT "users".* FROM "users" WHERE "users"."name" = $1 ORDER BY "users"."id" ASC LIMIT $2  [["name", "elengine"], ["LIMIT", 3]]

Using the pgpool_nlb option of the execute method will add a comment to the SQL.

irb(main):001:0> ActiveRecord::Base.connection.execute('SELECT 1')
  SELECT 1

irb(main):002:0> ActiveRecord::Base.connection.execute('SELECT 1', pgpool_nlb: true)
  /*NO LOAD BALANCE*/ SELECT 1

Bug reports and pull requests are welcome on GitHub at https://github.com/elengine/pgpool_no_load_balance. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the PgpoolNoLoadBalance project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.