chanks

-- The goal of this script is to trim messages that have been processed by
-- all extant groups from the a given Redis stream. It returns the number
-- of messages that were deleted from the stream, if any. I make no
-- guarantees about its performance, particularly if the stream is large
-- and not fully processed (so a simple XTRIM isn't possible).

-- First off, bail out early if the stream doesn't exist.
if redis.call("EXISTS", KEYS[1]) == 0 then
  return false
end

chanks

["/home/chris/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/monitor.rb:109:in `sleep'",
  "/home/chris/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/monitor.rb:109:in `wait'",
  "/home/chris/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/monitor.rb:109:in `wait'",
  "/home/chris/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/monitor.rb:121:in `wait_while'",
  "/home/chris/.rvm/gems/ruby-2.5.0@rails-test/gems/activesupport-5.1.6/lib/active_support/concurrency/share_lock.rb:219:in `wait_for'",
  "/home/chris/.rvm/gems/ruby-2.5.0@rails-test/gems/activesupport-5.1.6/lib/active_support/concurrency/share_lock.rb:81:in `block (2 levels) in start_exclusive'",
  "/home/chris/.rvm/gems/ruby-2.5.0@rails-test/gems/activesupport-5.1.6/lib/active_support/concurrency/share_lock.rb:185:in `yield_shares'",
  "/home/chris/.rvm/gems/ruby-2.5.0@rails-test/gems/activesupport-5.1.6/lib/active_support/concurrency/share_lock.rb:80:in `block in start_exclusive'",
  "/home/chris/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/monitor.rb:226:in `mon_synchronize'",
  "/home/chris

chanks

require 'sequel'
require 'logger'

DB = Sequel.connect "postgres:///scrap"

DB.loggers << Logger.new(STDOUT)

Sequel::Model.plugin :tactical_eager_loading

DB.drop_table? :posts

chanks

Turning PostgreSQL into a queue serving 10,000 jobs per second

RDBMS-based job queues have been criticized recently for being unable to handle heavy loads. And they deserve it, to some extent, because the queries used to safely lock a job have been pretty hairy. SELECT FOR UPDATE followed by an UPDATE works fine at first, but then you add more workers, and each is trying to SELECT FOR UPDATE the same row (and maybe throwing NOWAIT in there, then catching the errors and retrying), and things slow down.

On top of that, they have to actually update the row to mark it as locked, so the rest of your workers are sitting there waiting while one of them propagates its lock to disk (and the disks of however many servers you're replicating to). QueueClassic got some mileage out of the novel idea of randomly picking a row near the front of the queue to lock, but I can't still seem to get more than an an extra few hundred jobs per second out of it under heavy load.

So, many developers have started going straight t

chanks

module Sequel
  class Dataset
    class Query
      attr_reader :dataset

      def initialize(dataset)
        @dataset = dataset
      end

      def method_missing(method, *args, &block)

chanks

5275 6269 6e69 7573 2043 7261 7368 2052
6570 6f72 7420 2372 6278 6372 6173 6872
6570 6f72 740a 0a45 7272 6f72 3a20 7369
676e 616c 2000 5349 4753 4547 560a 0a5b
5b42 6163 6b74 7261 6365 5d5d 0a2f 686f
6d65 2f63 6872 6973 2f2e 7262 656e 762f
7665 7273 696f 6e73 2f72 6278 2d32 2e30
2e30 2d64 6576 2f62 696e 2f72 6278 5b30
7835 6239 6161 305d 0a2f 6c69 622f 7838
365f 3634 2d6c 696e 7578 2d67 6e75 2f6c

chanks

require 'rubygems'
require 'sequel'

DB = Sequel.sqlite

DB.create_table :questions do
  primary_key :id
  String :content
end

chanks

  it "should support creating new objects with composite primary keys" do
    a = @Artist.new({:name=>'Ar', :concerts_attributes=>[{:tour => 'To', :date => "2004-04-05"}]})
    @db.sqls.should == []
    a.save
    check_sql_array("INSERT INTO artists (name) VALUES ('Ar')",
      ["INSERT INTO concerts (tour, date, artist_id) VALUES ('To', '2004-04-05', 1)",
       "INSERT INTO concerts (artist_id, tour, date) VALUES (1, 'To', '2004-04-05')"
       ]) # etc.
  end

chanks

Loading development environment (Rails 3.2.2)
irb(main):001:0> DB.loggers << Logger.new(STDOUT)
=> [...array of loggers...]
irb(main):002:0> Problem.dataset.first
(0.001232s) SELECT * FROM "problems" LIMIT $1::int4; [1]
=> #<Problem @values={:id=>1, :content=>...}>
irb(main):003:0> Problem.dataset.use_cursor.first
(0.000347s) BEGIN
PGError: ERROR:  there is no parameter $1
LINE 1: ...SOR WITHOUT HOLD FOR SELECT * FROM "problems" LIMIT $1::int4

chanks

require "sequel"

DB = Sequel.sqlite

DB.create_table :users do
  primary_key :id
end

DB.create_table :quizzes do
  Integer :user_id