Learn in depth about Postgres driver implementation.

Postgres

Postgres driver uses pg client gem to talk to database. It uses INSERT with ON CONFLICT resolution and regular SELECT to interact with database.

Configuration

You can configure driver directly using pg gem.

require 'pg'

Trifle::Stats.configure do |config|
  config.driver = Trifle::Stats::Driver::Postgres.new(
    PG.connect('postgresql://postgres:password@postgres:5432/stats?sslmode=require')
  )
end

Or if you are using rails with pg, you can reuse ActiveRecord connection.

Trifle::Stats.configure do |config|
  config.driver = Trifle::Stats::Driver::Postgres.new(
    ActiveRecord::Base.connection.instance_variable_get('@connection')
  )
end

Setup

Postgres driver requires trifle_stats table to be present. You can override table_name when creating an instance of a driver.

You can create table and index on your own, using below rails migration or simply call setup! class method that does this for you. It creates a table and adds an unique index on a key column.

Use this Rails migration to create trifle_stats (or name it your own).

create_table :trifle_stats, id: false do |t|
  t.string :key, null: false, primary_key: true
  t.jsonb :data, null: false, default: {}
end

Below is a setup and configuration for a custom database and a table name.

Trifle::Stats::Driver::Postgres.setup!(
  PG.connect('postgresql://postgres:password@postgres:5432/stats'),
  table_name: 'my_stats'
)

Trifle::Stats.configure do |config|
  config.driver = Trifle::Stats::Driver::Postgres.new(
    PG.connect('postgresql://postgres:password@postgres:5432/stats'),
    table_name: 'my_stats'
  )
end

Driver

You can either use your current pg connection, or pass in instance of custom pg connection.

irb(main):001:0> client = PG::Connection.new
=> <PG::Connection:0x00007ff109a6d1f8>
irb(main):002:0> driver = Trifle::Stats::Driver::Postgres.new(client)
=> #<Trifle::Stats::Driver::Postgres:0x00007ff109c88028 @client=#<PG::Connection:0x00007ff109a6d1f8>, @table_name="trifle_stats", @separator="::">

Interaction

Once you create an instance of a driver, you can use it to set, inc or get your data.

irb(main):003:0> driver.get(keys: [['test', 'now']])
=> [{}]

irb(main):004:0> driver.inc(keys: [['test', 'now']], count: 1, success: 1, error: 0)
=> {"count"=>1, "success"=>1, "error"=>0}
irb(main):005:0> driver.get(keys: [['test', 'now']])
=> [{"count"=>1, "error"=>0, "success"=>1}]

irb(main):006:0> driver.inc(keys: [['test', 'now']], count: 1, success: 0, error: 1, account: { count: 1 })
=> {"count"=>1, "success"=>0, "error"=>1, "account.count"=>1}
irb(main):007:0> driver.get(keys: [['test', 'now']])
=> [{"count"=>2, "error"=>1, "success"=>1, "account"=>{"count"=>1}}]

Performance

inc and set operations are executed for each key/pair value in a single query. Queries for each key in keys is executed in a single transaction. It also queries data in a single query for each key in keys.