codesnips

postgres

go 
package dbutil

import (
  "context"

  "github.com/jackc/pgconn"

Retry Postgres serialization failures with bounded attempts

go postgres transactions
by Leah Thompson 1 tab
ruby 
require "csv"

class PeopleCsvStream
  include Enumerable

  HEADERS = %w[id full_name email signed_up_at plan].freeze

Resilient CSV Export as a Streamed Response

rails performance streaming
by codesnips 3 tabs
ruby 
class AddSettingsToAccounts < ActiveRecord::Migration[7.1]
  disable_ddl_transaction!

  def change
    add_column :accounts, :settings, :jsonb, null: false, default: {}

Postgres JSONB Partial Index for Feature Flags

rails postgres jsonb
by codesnips 3 tabs
ruby 
module EmailNormalization
  extend ActiveSupport::Concern

  included do
    attr_accessor :soft_warnings

Soft Validation: Normalize + Validate Email

rails activerecord validations
by codesnips 4 tabs
ruby 
class CreateTopSellersMv < ActiveRecord::Migration[7.0]
  def up
    execute <<~SQL
      CREATE MATERIALIZED VIEW top_sellers AS
        SELECT p.id            AS product_id,
               p.name          AS product_name,

Cache-Friendly “Top N” with Materialized View Refresh

rails postgres performance
by codesnips 4 tabs
ruby 
class CreateDeadJobs < ActiveRecord::Migration[7.1]
  def change
    create_table :dead_jobs do |t|
      t.string  :jid, null: false
      t.string  :queue, null: false
      t.string  :klass, null: false

Background Job Dead Letter Queue (DLQ) Table

rails reliability background-jobs
by codesnips 4 tabs
ruby 
class PostsController < ApplicationController
  def index
    posts = Post.for_feed.page(params[:page]).per(25)

    render json: {
      data: posts.map { |post| PostSerializer.new(post).as_json },

N+1 Proof Serialization with preloaded associations

rails activerecord performance
by codesnips 3 tabs
ruby 
class ReportQuery
  SQL = <<~SQL.freeze
    SELECT date_trunc('day', events.created_at) AS day,
           count(*) AS total,
           count(*) FILTER (WHERE events.kind = 'purchase') AS purchases
    FROM events

Safe Raw SQL with exec_query + Binds

rails activerecord sql
by codesnips 2 tabs
go 
package store

import (
  "context"

  "github.com/jackc/pgx/v5"

Postgres transaction pattern with pgx: defer rollback, commit explicitly

go postgres pgx
by Leah Thompson 1 tab
go 
package store

import (
  "context"
  "database/sql"
)

sqlc transaction wrapper that keeps call sites clean

go sql postgres
by Leah Thompson 1 tab
ruby 
class Tag < ApplicationRecord
  has_many :taggings, dependent: :destroy

  scope :top, ->(limit = 20) {
    joins(:taggings)
      .group(Arel.sql("tags.id"))

Memory-Safe “top tags” aggregation with pluck + group

rails activerecord performance
by codesnips 3 tabs
ruby 
require "timeout"

module HealthCheck
  class Probe
    Result = Struct.new(:name, :status, :latency_ms, :critical, :error, keyword_init: true) do
      def healthy?

Health Check Endpoint with Dependency Probes

rails reliability health-check
by codesnips 3 tabs