Ganeshan

Ganeshan is a gem to find slow query with EXPAIN for postgreSQL.

Installation

Add this line to your application's Gemfile:

gem 'ganeshan'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install ganeshan

Usage

You can enable it with config/environments/development.rb

Ganeshan.enabled = true

Or You can use it without rails, but with active_record.

#!/usr/bin/env ruby

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"
  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "ganeshan"
end


require 'active_record'
require 'ganeshan'

ActiveRecord::Base.establish_connection(
  host:     '127.0.0.1',
  adapter:  'postgresql',
  username: 'hoge',
  password: 'password',
  database: 'ganeshan'
)

Ganeshan.enabled = true

ActiveRecord::Schema.define do
  create_table :products, force: true do |t|
    t.text :name
  end
end

class Product < ActiveRecord::Base
end

p Product.all.to_a.count
p Product.all
p Product.limit(1)
p Product.where(id: 1).limit(10)

then, output is like this.

Ganeshan  INFO    2020-08-14 02:30:34 +0900       {
  "sql": "SELECT \"products\".* FROM \"products\"",
  "explain": [
    {
      "line": 1,
      "QUERY PLAN": "Seq Scan on products  (cost=0.00..22.00 rows=1200 width=40)"
    }
  ]
}
2

Ganeshan  INFO    2020-08-14 02:30:34 +0900       {
  "sql": "SELECT \"products\".* FROM \"products\" LIMIT $1",
  "explain": [
    {
      "line": 1,
      "QUERY PLAN": "Limit  (cost=0.00..0.20 rows=11 width=40)"
    },
    {
      "line": 2,
      "QUERY PLAN": "  ->  Seq Scan on products  (cost=0.00..22.00 rows=1200 width=40)"
    }
  ]
}
#<ActiveRecord::Relation [#<Product id: 2, name: "test2">, #<Product id: 1, name: "test1">]>

Ganeshan  INFO    2020-08-14 02:30:34 +0900       {
  "sql": "SELECT \"products\".* FROM \"products\" LIMIT $1",
  "explain": [
    {
      "line": 1,
      "QUERY PLAN": "Limit  (cost=0.00..0.02 rows=1 width=40)"
    },
    {
      "line": 2,
      "QUERY PLAN": "  ->  Seq Scan on products  (cost=0.00..22.00 rows=1200 width=40)"
    }
  ]
}
#<ActiveRecord::Relation [#<Product id: 2, name: "test2">]>

Ganeshan  INFO    2020-08-14 02:30:34 +0900       {
  "sql": "SELECT \"products\".* FROM \"products\" WHERE \"products\".\"id\" = $1 LIMIT $2",
  "explain": [
    {
      "line": 1,
      "QUERY PLAN": "Limit  (cost=0.15..8.17 rows=1 width=40)"
    },
    {
      "line": 2,
      "QUERY PLAN": "  ->  Index Scan using products_pkey on products  (cost=0.15..8.17 rows=1 width=40)"
    },
    {
      "line": 3,
      "QUERY PLAN": "        Index Cond: (id = '1'::bigint)"
    }
  ]
}
#<ActiveRecord::Relation [#<Product id: 1, name: "test1">]>

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

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

License

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

Code of Conduct

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